Category Archives: Botany

Latitudinal Diversity: my theory


Growing up in England I was fond of woods, but when I went to live in a cloud forest (which is a tropical rainforest in the mountains) in central America, three things stood out as massively different to the forests I knew in England.

  1. There was a huge variety of plants. In the UK, most woods have the same few trees and plants repeated – oaks, birches, sycamores and ash for the trees; bracken and brambles at ground level. In the cloud forest, almost no tree or ground level plant was repeated, to put it technically, it had a greater species diversity.
  2. The ecosystem was far more interactive than I was used to. Trees were laden with epiphytes, and there was barely a leaf without fungus, insects or a virus. It seemed that almost every plant surface had something else growing on it. In the UK, there are only occasional galls and nests, the odd bit of moss, and epiphytic plants are rare.
  3. The variety in colour, shape and habit of the cloud forest plants was huge, at every turn I uncovered new leaf shapes and colours, whereas in the UK there are mostly green leaves growing in a few different patterns. (Note that I am talking about native woods in the UK here, we import many different garden plants from other countries and those have a greater variety of shapes and colours)


The differences were so immense and fascinating, I started researching as soon as I was able to.

What I discovered is that there is higher diversity of species and greater number of species (species richness) the closer to the equator you get. This is known as the latitudinal diversity gradient.

Science hasn’t quite explained it yet, but there are theories, I also have my own which I want to share. I’ve not come across anyone suggesting the same explanation, although the chances someone has, somewhere.


An aroid flower in Ecuador

The Facts

  • The greatest number of species for the major taxa – flowering plants, ferns, mammals, birds, reptiles, fresh water fish, amphibians, insects and snails – are in the tropics.
  • Species diversity and richness increase as you travel towards the equator.

For example: The 1950s doc ‘Evolution in the Tropics’ by Dobzhansky stated that Greenland had 56 species of birds, New York 195, Guatemala 469, Panama 1100 and Colombia 1395.

  • While tropical moist forests have the greatest diversity, even tropical savannahs and grasslands are more diverse than similar landscapes in temperate areas. This is especially important, because it suggests that the difference is not just due to terrain, but also latitude.
  • Recent research suggests that there are more fungi species in the tropics too. There isn’t enough known about diversity of bacteria species across the globe.

A pink-leaved climber growing within a green-leaved plant.

The Theories

There are a number of theories. They include factors such as the Ice Age, which affected the poles greatly and the tropics less so; the size of the tropics compared to other areas; and the higher levels of predation so that the fight to survive drives evolution. All of the theories are contested, a few can explain part of the difference, but not all. Some are circular, eg. there is greater species diversity, because there are more competitors for food sources.

For more detail try A Neotropical Companion by Kricher (where much of my info comes from) or Wikipedia which has a number of other theories too.


My Theory – it’s all about the small things

One notable difference about the equator is that there is little change in light and temperature. Where as in the UK the nights are very long in the winter and short in the summer, in Central America it gets dark at 5pm all year round. Temperatures are also more stable; slightly closer to the poles, the more temperatures can fluctuate from minus degrees in the winter to scorching heat in the summer. In the tropics, it’s pretty much hot all year round – or in high up cloud forests it’s consistently warm.

This lack of change makes some difference to larger animals and plants since they don’t need to go into dormancy they can grow and reproduce all year round. But their life cycles are still fairly slow, reproducing once a year or every few years. However, this difference is far more significant when it comes to very small organisms because their lifecycles are so much shorter, and they are more affected by changes in temperature and light. Those quick lifecycles mean they can mutate, adapt and evolve at far greater rates too.

So I believe that is why there is greater species richness, abundance and diversity of small organisms at the equator, but the difference is not so pronounced in larger organisms, so what else is a factor?

I believe that it is the species diversity of smaller organisms that directly causes the diversity in larger organisms through parasitism and symbiosis. Parasitism drives evolution and symbiosis aids survival.


First, some terminology


Parasites are usually insects, fungi, small plants or bacteria and are harmful to larger plants and animals, taking what they need without concern for the host. Organisms often evolve to protect themselves from threat. Parasites are a threat. The more threats, and the more varied the threats, the more animals and plants need to evolve to fight them. This is a common, but as yet unproved theory.

For example: If a plant has a mutation of hairy leaves that deter insects, then in an environment with many insects, that mutation is more likely to lead to the survival of that plant and the proliferation of the hairy-leaf gene.


Symbiosis between insects and fungi?


Symbiotic relationships tend to drive specialisation and help organisms to survive. Because the rainforest is so crowded, there is a constant battle for nutrients, space and light, so forming an alliance is beneficial. Through the generations, that alliance tends to become tighter and more exclusive. Symbiosis can be seen between many animals, plants, fungi and bacteria.

For example:  Ants forming a protective army inside an acacia tree and fighting off any animal that comes to eat it. Or aroid flowers that are only pollinated by one type of fly, so they evolve to give off a scent that attracts that specific fly (often rotting meat). In a crowded rainforest, if all plants targeted all insects, then many plants would get missed and never pollinated. Forming a symbiotic relationship is like putting an address on a letter, instead of flinging up in the air and hoping someone reads it.

The Small Things


Fungus in Ecuador

The ideal conditions for fungi to grow are warm moist ones. In the UK fungi live in the ground unseen, all year round. Then in autumn they produce fruiting bodies – ie the mushrooms that enable them to reproduce – that’s because the soil has warmed over the summer and there’s plenty of rain. In the tropics, the soil never cools, and humidity is constant, this means the reproductive phase can also continue all year round.




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Why fungi are important to larger organisms – fungi can be both beneficial and harmful to plants. Some fungi form a symbiotic relationship with them, growing on their roots and enabling them to take in nutrients that the plants would struggle to access on their own – these are known as mycorrhizal fungi. This harmoniuos relationship can take centuries to form. This is one reason why it’s so difficult to regrow plants on an area that has been de-forested, because the mycorrhizal fungi are no longer there, and the plants can’t access nutrients without them.

Fungi can also be parasitic and break down healthy wood. That’s what fungus does essentially, breaks stuff down, it’s a decomposer – that’s good when it’s breaking down dead matter to release the nutrients, but bad when it breaks down living material.



Either bacteria or insect galls

Like fungus, the ideal conditions for bacteria to grow is warmth and moisture, they are also sensitive to light changes. So, the equator, and especially the rainforest at the equator, has perfect conditions.

Why is bacteria important to larger organisms – like fungi, bacteria can be both good and bad for plants. Some bacteria work in a similar way to fungi, attaching to roots and breaking down nutrients (specifically nitrogen) into a form the plants can absorb. And, like fungi, bacteria can be harmful, causing diseases.





Insects also like warmth and wet. We know in the UK if there is a warm summer followed by a lot of rain, then the insects will increase. In the tropics, those are the constant conditions. Even in drier areas, the consistency of temperature is enough to maintain insect populations.

Why insects are important to larger organisms – insects can also be a blessing or a burden to plants. Leaf cutter ants will ravage a tree, defoliating it, but as described above, ants can protect trees too. The photo above shows a number of insect galls on plants, where parasitic insects alter how a plant grows to create their habitats.






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To put it simply…

According to my theory,

  • Smaller organisms thrive in stable environments where light and temperatures are fairly constant all year round.
  • The resulting high numbers and quick life cycle leads to greater opportunities for them to mutate and evolve.
  • Smaller organisms affect the number and diversity of larger organisms through parasitism and symbiosis.
  • Parasitism drives species richness, by forcing larger organisms to evolve to survive. Symbiosis aids survival and promotes specialisation.
  • So the numbers and diversity of larger organisms increases.



Mosses and lichen on a branch



Why don’t we ban Glyphosate? (Round Up)

Mendoza GL 2

Abandoned station as the plants reclaim…

There’s been a lot of publicity surrounding the herbicide Glyphosate, the main ingredient in Round Up. A recent court case determined that it can cause cancer. It has also been found in streams and some water supplies. The media have been vocal in the dangers of this terrible chemical, and people must be wondering: why hasn’t it been banned?

The problem is, there is pretty much no other effective herbicide to use.

As someone who’s worked for a number of gardening companies and in a number of large gardens, it’s been the only non-selective herbicide I’ve come across (non-selective means it kills all plants). However, I was aware a number of countries had banned it, so I was convinced there must be something else to use. It’s been bugging me for a while, so thought I’d do a bit of investigating.

Why Do We Need a Herbicide Anyway?


Plants can grow anywhere

Naturally, when most people think about banning herbicides, they worry about the patios and paths in their gardens, but it’s a little more serious than that. It’s not surprising people think of plants as mostly well-behaved organisms, because that is how we keep them, manicured and contained. But plants have been colonising land since long before animals ever did, and they’re very good at it. If all humans suddenly vanished, it would only be a few years before plants had made headway in reclaiming roads and buildings.

Many plants don’t need a nice flowerbed in order to grow, plenty don’t need soil at all.

How plants take over a hostile space

First moss and liverworts grow on bare rock, then when they die their decomposing leaves provide a little bit of soil for slightly bigger plants, which have more tenacious roots that ease into cracks. Then they die and create more soil. Soon there is enough soil for plants with tougher roots to sprout, and the cracks widen further. Once there’s a perfect environment for invasive weeds to take hold, it can be only a few months before waist high clumps are sprouting up in great numbers. And this can happen anywhere, on railway tracks, pavements, roads, even through walls.

Buddleia GL

Buddleia growing in railway arch walls

When it comes to invasive weeds, Buddleia (Buddleia davidii) and Japanese knotweed (Fallopia japonica) are the biggest problems, and a problem that only Glyphosate solves. Whereas plants such as Himalayan Balsam (Impatiens grandulifera) and Skunk Cabbage (Lysichiton americanus) tend to be confined to wet areas, Buddleia and knotweed can and do grow anywhere. Buddleia can grow in walls, knotweed can break through concrete. These plants are kept in check by Glyphosate, and whole companies exist to remove them. I studied for my spray certficate with a couple of guys whose sole job it was to inject Japanese Knotweed with Glyphosate. Without chemical intervention, these tough innovative plants would take over, and soon they would affect the running of trains, and damage buildings and roads. Pulling them out acheives little. Pull Buddleia out of a wall and you’ll damage the wall. Pull knotweed out of the ground and you’ll cause more shoots to sprout in their place like a Hydra from Greek mythology. A solution needs to be tough.

How Have Countries Banned Glyphosate?

Whenever trouble with Glyphosate raises its head, the media talks of countries which have banned it, so why can’t we? Looking deeper into this leads to some interesting caveats to the bans. Although 14 countries are reported as having bans, few have an outright ban.

Some countries, such as Belgium and the Netherlands have restricted use (only for commercial use or to treat invasive weeds). Some are undergoing the slow process to find alternatives and intend a ban in a few years time (eg France). Bermuda started out with an outright ban, then relaxed the laws. Canada has banned it except in the case of invasive weeds.

A number of countries such as Saudi Arabia, Kuwait, Qatar, Bahrain, Oman and the United Arab Emirates have an outright ban. I haven’t been able to find out why, but maybe there is a large lower-wage workforce there, who will do the weeding by hand. There are certainly invasive weeds in the Middle East, although many are dependent on irrigation provided by humans, so that may be  a factor. (If anyone knows the reason, please email me at the address at the bottom of this blog and I’ll update).

Despite headlines calling for a ban, it looks like the solution is more complicated.

What are the alternatives?

Salt – this is often cited, however, Sodium Chlorate, a derivative of salt used as a herbicide, is banned in Europe. Using it on a few weeds in one garden isn’t such a big deal, but using large amounts on train tracks could be an environmental disaster. It depletes the ozone layer and is harmful to aquatic life. It’s also toxic to humans.

Vinegarwas used in Bristol to control weeds for a year. It was found to be not cost effective and not have such a long-lasting effect as Glyphosate. Personally, I’d be concerned at the environmental effect of throwing large quantities of vinegar around. Large quantities of anything that kills plants can cause environmental harm.

Handweeding – this is incredibly slow and isn’t practical on a large scale. It would mean shutting down roads and train tracks and new purpose-built machinery and a lot of cheap labour. Fine for private gardens though.

Mulching – useful in flower beds, but useless on paths and patios and won’t stop plants that grow out of walls or through buildings.

Steam weeding (sometimes called Heat Weeding) – this involves a machine that sprays out water at 99 degrees. I’ve used one, it is effective, although still in its infancy, so the machine is cumbersome and not very versatile yet. It’s being trialled mainly in Australia and Sweden. Given time, it’s one of the best options and there needs to be investment, plus government incentives to use it.

Fire – not setting fire to the weeds, but running a flame over them. Another good possibility. Not something I’ve used, but I can see how it would work on open ground. I don’t know the logistics of using it on buildings, but it’s a possible solution.

And Finally…

I’m concerned that this blog may come across like I’m resigned to chemical use and I really don’t want that. This is a beautiful world, we’ve been messing with it for a long time and we’re starting to feel the terrible consequences of that. So it’s time to grow up as a species and start taking better care of our surroundings. One way to do that is to reduce chemical use and work with nature in a sustainable and less intensive way. There will be ways to reduce and eventually get rid of Glyphosate, but in order to do that, we need to accept it’s not just a matter of banning one chemical and then moving onto another.

If anyone has any knowledge or ideas to add to this, then drop me a line at therealtetrapod at gmail dot com. Thank you!

Mendoza Glyphosate

Another picture of Mendoza station, just because…


How to Make a Rainbow Rose

My first thought on seeing one of these was, how do they do that? Well, I think I’ve figured it out…

Rainbow rose

Picture credit: my mum


I bought a rainbow rose for my mum on Mother’s Day, I guessed she’d be as curious as me to know how they make them. After having a think and looking at the base of the stem it became clear.

A normal, wrong-coloured rose is created by simply putting the end of the stem in food colouring (mixed with water), the plant then sucks it up as it would normal water, and the colour spreads throughout the stem, leaves and flowers.

Lengthways section through a rainbow rose

Lengthways section through a flower stem

cross section rainbow rose stem

Cross section through a flower stem showing different colours inject into the xylem

For a mutli-coloured rose it takes more precision, but the idea is the same. A different coloured dye is injected into each of the xylem tubes, these are around the edge of the stem and take water through the plant. Because the xylem tubes stretch from one end of the plant to the other, and do not merge, the food colouring remains separate, all the way to the petals, so that each petal is flooded with a different colour.

The evidence for this is small dots of colour around the edge of the cut stem, where the dye was injected in.

RHS Level 3: Plant taxonomy, structure, and function

  1. Understand the Plant Kingdom and the taxonomic hierarchy.

1.1 Describe the major groups of the Plant Kingdom.

List the main groups within bryophytes, pteridophytes, gymnosperms and angiosperms.

This is quite an archaic way of grouping plants. The kingdom Plantae is usually divided into 10 divisions, listed below, with the groups in the syllabus in bold. Gymnosperms consists of Pinophyta, Cycadophyta and Ginkgophyta. Angiosperms = Magnoliophyta:

  • Anthocerotophyta – hornworts
  • Marchantiophyta – liverworts
  • Bryophyta – mosses
  • Lycopodiophyta – club and spike-mosses
  • Pteridophyta – ferns and horsetails
  • Gnetophyta – 3 extant genera of woody plants
  • Cycadophyta – cycads
  • Ginkgophyta – Ginkgo
  • Pinophyta/Coniferophyta – conifers
  • Magnoliophyta – flowering plants

Plant Characteristics

Describe and compare the structural and reproductive characteristics of: mosses, ferns, conifers and flowering plants in relation to their adaptation to terrestrial life.


I’ve written about these four groups previously, the information about structural and reproductive characteristics is in the first two paragraphs of each blog

  1. Mosses
  2. Ferns
  3. Conifers
  4. Flowering Plants

Brief description of reproductive characteristics:

Bryophytes – have sporophyte and gametophyte stages. Gametophyte is dominant.

Pteridophytes – have sporophyte and gametophyte stages. Sporophyte is typical fern, gametophyte is small and rarely noticed.

Gymnosperm – have male and female cones. Male cones drop pollen which is carried by wind.

Angiosperm – have flowers that may be dioecious, monoecious or hermaphrodite. Usually wind or insect pollinated (but other methods of pollination exist).

1.2 Describe features of plant classification and nomenclature relevant to horticulture.

State the hierarchy of botanical units and explain how and when they are used.

To include: family, genus, species, subspecies, varietas, forma.

To include ONE NAMED plant example for EACH of the above terms showing how it is written.


Have the ending -aceae (many family names were recently changed to conform to this). Plant families are usually named after the biggest or most well known genus in that family. eg Euphorbiaceae, the family that the genus Euphorbia is in.


Genus is a subdivision of family. The genus of a plant is used as the first part of its binomial name, and is always capitalised. It should be written in italics (or underlined). eg Euphorbia.


Species is a subdivision of genus. The species of a plant is used as the second part of its binomial name and is never capitalised. It should be written in italics (or underlined). eg characias  (as in Euphorbia characias.)


Recommended abbreviation is subsp. but ssp. is sometimes used. Subspecies are written in small italics, but the word subsp. is not. A subdivision of species. Plants within different subspecies but within the same species are capable of interbreeding, but don’t due to geographical separation. eg Euphorbia characias subsp. wulfenii.


A subdivision of species, similar to subspecies (and the two terms often overlap) however, different varieties within a species may geographically overlap, unlike subspecies. Recommended abbreviation is var. Varieties are written in italics, but var. is not. eg Malva alcea var. fastigiata.


If a plant shows uncharacteristic appearance of its species (such as habit or colour) then it can be known as a different form. These differences are usually due to environmental reasons and won’t be passed to the next generation. Recommended abbreviation is f. The form is written in italics, but f. is not. eg Vinca minor f. alba.

Explain the meaning and use of the terms: cultivar, Group, trade designation (selling name), Plant Breeders’ Rights, interspecific, intergeneric and graft hybrids, naming authority.

To include ONE NAMED plant example for EACH of the above terms, showing how it is written.

Cultivar: This is short for ‘cultivated variety’ and refers to plants that have been bred for their characteristics. The names are often chosen as a selling point, for example using somebody’s name, making them a good present for people of the same name. eg Clematis ‘Willy’ (note the cultivar name is capitalized, in single quotes and not italicized. Because of the complexity of cross breeding across species, the species of a cultivar is only sometimes used.)

Group: If several cultivars are similar, they can be grouped together to make customer selection easier. eg Lilium Darkest Red Group (note the group is capitalized, not italicized, and not in quotes.)

Trade designation: Cultivar names cannot be legally protected. If a plant breeder wishes to keep sole legal rights to a plant, then he/she uses a trade name. This a commercial synonym that is legally protected. eg Rosa FASCINATION = Rosa ‘Poulmax’. (note: the writing method for ‘Fascination’ changes, sometimes it is in quotes, like a cultivar; other times it is in square brackets. The correct notation is all in capitals, not italicized, not in quotes, often in a different font.)

Plant Breeders’ Rights: Breeders using a Trade designation have Plant Breeders’ Rights which are recognised internationally. If you own the rights to a cultivar, it cannot be bred by anyone else without your permission. If somebody buys one specimen of your cultivar, you still have exclusive rights to all propagation material of that plant: seeds, cuttings etc.

Interspecific, intergeneric and graft hybrids: Unlike with animals, plants can be bred across species and genera. Plants of different genera can, in some cases, be grafted together, occasionally this will lead to a mixing of cells where the scion and the rootstock meet, this is not a true hybrid. It is also known as a graft chimaera.


  • Interspecific hybrid –  Mahonia × media (bred from Mahonia lomariifolia and Mahonia japonica, note the ‘x’ in the middle and new specific epithet.)
  • Intergeneric hybrid× Cupressocyparis leylandii (bred from Cupressus macrocarpa and Chamaecyparis nootkatensis, note the ‘x’ at the beginning and the genus which is a combination of the parents’).
  • Graft hybrid – +Laburnocytisus ‘Adamii’, (a graft hybrid between Laburnum and Cytisus, note the ‘+’ at the start and genus which is a combination of the parents’.) This graft contains flowers of Laburnum and Cytisus (ie both yellow and purple) but also flowers that are a pinky colour, a mix of the two.

Naming authority: The International Cultivation Registration Authority is a naming authority, responsible for seeing that cultivar names are not duplicated.

State the significance of the ICN (The International Code of Nomenclature for algae, fungi and plants) formerly ICBN (International Code of Botanical Nomenclature) and the ICNCP (International Code for Nomenclature for Cultivated Plants) in the naming of plants.

The ICN (The International Code of Nomenclature for algae, fungi and plants) A code that governs plant discoveries in the world – ensuring that plants aren’t given different names by different discoverers, or that already named plants aren’t given new names without reason.

International Code of Nomenclature website Contains complex set of rules to standardise naming and classification eg changing all plant families to end in -aceae, Compositae > Asteraceae.

ICNCP (International Code for Nomenclature for Cultivated Plants) – a code that governs the naming of newly created cultivars.

Cultivated Plant Code

(For more information about the latest ICNCP, there’s an interesting article on Gardening Wizards, here)

Explain the reasons for name changes: reclassification (scientific research, new discovery), changes in nomenclature (rule of priority), incorrect identification.

To include TWO NAMED plant examples for EACH.

Reclassification (scientific research, new discovery)

  1. With advances in DNA technology, African Acasias were found to not be related to Australian Acasias. Australian Acasias have kept their name, while African have become Vachellia or Senegalia.
  2. Coleus became Solenostemon, but was then found to be part of the Plectranthus genus. Plectranthus scutellarioides used to be Coleus blumei.

Rule of priority

This is where a plant is discovered to have been named previously, and its old name is found on record. When an existing name is discovered, the plant should revert to this name, but occasionally, if the new name is far more familiar it will be kept.

  1. Platanus ×acerifolia was the name of the London Plane, but this name was recorded in 1805 and it was discovered later that an earlier name of Platanus ×hispanica had been recorded in 1770. Therefore Platanus ×hispanica became the official name.
  2. Festuca subgenus Schedonorus was moved to the genus Lolium and its name became Lolium subgenus Schedonorus.

Incorrect identification

Sometimes a name change is due to a simple mistake, when one plant becomes mixed up with another.

  1. Archontophoenix cunninghamiana was for a long time incorrectly sold as Seaforthia elegans.
  2. Syzygium australe was often sold as Syzygium paniculatum

 Explain how plant names can indicate: plant origin, habitat, commemoration, colour, growth habit, leaf form.

To include TWO NAMED plant examples for EACH. 

It is often the plant species that indicates origin, colour etc, but not always (see below). The Latin will only refer to one characteristic (when Latin plant names were first used, botanists tried to include every characteristic, leading to ridiculously long names, then Linnaeus reduced it to two).

Plant origin: Mahonia japonica (Japan), Arum italicum (Italy)

Habitat: Clematis alpina (alpine plants), Pinus sylvestris (wood or forest)

Commemoration: Photinia fraseri (John Fraser1750-1811 nurseryman), Weigela (Christian Weigel 1749-1831 German botanist)

Growth: Briza maxima (large or largest), Vinca minor (smaller)

Habit: Cotoneaster horizontalis (growing horizontally), Phlomis fruticose (shrubby)

Leaf form: Acer palmatum (palmate leaves), Ilex aquifolium (pointed leaves)

Schachen Alpine Garden

landscape  3

Schachen Landscape

Open four months of the year and accessible only on foot, the Schachen Alpine Garden contains plants from all over the world. As can be seen in the photos, Schachen is often foggy, and despite being surrounded by the Alps, we barely saw them.

Alpine plants have a few conditions in common no matter where they are from; they have to cope with extreme cold (Schachen is often covered with snow), a short growing season, high winds, and a lack of rain. Alpine plants are mostly small and low growing, this enables them to flower in the short time when the conditions are favourable and keep below the high winds.

Anthyllis vulneraria 2

Anthyllis vulneraria


A number of plants had an ability to repel water and hold it in droplets above the leaves, I think this is a way of protecting them when covered in snow, stopping the leaves from being damaged. (see photos below)

Due to the mix of rock types on the mountain, the soil is very varied, with alkaline and acid soils side by side. This means that acid loving and alkaline loving plants that would never normally grow together, do. For example, this wild Clematis alpina (alkaline) and pine tree (acid). (see below)

Clematis and pine

Clematis alpina growing on a pine

Many of the pine trees on the mountain are growing right out of the rock (see photos below). In autumn animals bury seeds in the rock to serve as food stores for the winter. Many of these seeds are forgotten, and then germinate.

The photo below is of an unusually shaped Campanula, nothing like the normal bell-shaped flower. Because of its shape it is known as devil’s claw.


Devil’s Claw Campanula

Cows feed on the vegetation on the mountain. As it gets warmer, and the cows eat all the vegetation lower down, they are moved up higher. This can cause problems, because the cows will eat almost everything but Rheum (a genus containing rhubarb) because it is poisonous. As a result, the Rheum starts to take over, so there is a problem with this turning the mountain landscape into a monoculture. Rheum is the large-leaved plant in the photo below.

Mosses and lichens were in abundance in Schachen.

lichen 6

Lichen growing on pine tree

Wild orchids grew on the mountain also.

My favourite two photos from the trip:


Thistle flower


Red spotted bug

landscape  5.JPG

Schachen Alpine Garden



Plant Families: Araceae (aka Aroids or Arums)

Zantedeschia Inflorescence

Zantedeschia Inflorescence

A Few Basic Facts

  • Aroids are monocots in the family Araceae (aka arum family), in the order Alismatales. Most other families in this order contain tropical or aquatic plants, eg Hydrocharis and Saggitaria.
  • Araceae has 104-107 genera. The largest genus is Anthurium with over 700 species.
  • Location: Latin American tropical regions have the greatest diversity of aroids, however, they can also be found in Asia and Europe. Australia has only one endemic species – Gymnostachys.
  • Habitat: Aroids can be aquatic (water), epiphytic (air) and terrestrial (ground). Most are tropical, but there are also arid and cold loving aroids.
  • Distinctive features: All have an inflorescence (a structure containing a group of smaller flowers) which consists of a spadix (always) and a spathe (sometimes).

Aroid Flowers

  • Aroids can be hermaphrodite (each flower is both male and female), monoecious (male and female flowers on the same spadix) or dioecious (male and female flowers on completely different plants).
  • This family contains one of the largest flowers (Amorphophallus titanium, the titan arum) and the smallest (Wolffia, duckweed).
  • Some aroid leaf and inflorescence shapes:
Aroid Leaf Shapes

Aroid Leaf Shapes


Aroid Leaves


Aroid Fruits


Like many tropical families, aroids have evolved a number of adaptations to stay healthy and propagate. Some examples of adaptation:

  • The spathe protects the flowers and in some cases is used to trap insects for pollination. It is not a petal, but a modified leaf. Many spathes turn green and photosynthesize after flowering has finished.
  • Aroids have different types of roots adapted to their purpose. They have different adventitious roots  for climbing, attaching to rocks or taking in water.
  • Many tropical species have shiny leaves to deter the mosses and lichens that grow in abundance in the rainforest.
  • Smell is used by many species to attract pollinators. The smell of rotting meat, fungi and excrement is used for flies and beetles. Fragrant scents are used to attract bees.
  • In many species the spadix actually heats up and can reach 25°C, even in near freezing conditions. This increases the release of smells to attract pollinators. The heat also makes visiting insects more active.
  • Aroids that want to attract flies and beetles often have a warty, hairy, twisted appearance, with dark colours. This is to mimic the effect of dead animals, fungi or excrement.
  • In some species, leaves may change shape from juvenility to adulthood – changing from variegated to unvariegated, pale red to green, or altering the number of lobes of the leaf. Colour change may deter animals from feasting on the fresh young leaves by making them look less leaf-like.
  • Most species in Araceae have tubers or rhizomes, this means a damaged plant has the food storage and ability to grow new shoots from many points beneath the ground. Some aroids have other means of vegetatively propagating themselves, such as bubils and offsets.
  • A number of aroids are poisonous, some are edible. Aroids have evolved poisons in some species as protection. Those that are edible did not evolve to be eaten by us, rather we have evolved to be able to eat certain plants.



Male and Female Flowers

Because many aroids are monoecious there is a danger of self-pollination. While self-pollination is easy (a guaranteed fertilisation), it leads to less genetic variety and less ability to adapt to changes in the environment. Aroids are particularly variable plants, in one small area of the Thai Peninsula 22 distinct varieties of the plant Aglaonaemia nitidum f. curtisii were found. However, in order to achieve this variation, the plant needs to cross pollinate reliably. It does this by being protogynous, meaning the female flowers on an inflorescence ripen first and then later male flowers produce pollen.

The Generic Process for Monoecious Aroids

A beetle, fly or bee (hopefully covered in pollen) is attracted by the scent given off by the heated spadix. The insect flies around inside the spathe, lands on the slippery surface and falls into the gap between the spadix and spathe. At this point only the female flowers are mature, and the  insect, made more active by heat from the spadix, moves about bumping into the flowers and depositing the pollen. Now, the insect has fulfilled the first part of its function, the aroid would like it to pick up pollen from the male flowers. However, the male flowers will not ripen for a day or so yet, so the insect needs to be held hostage. The slippery spathe ensures that the insect can’t escape, it is given sustenance in the form of nectar. Once the male flowers are ready and producing pollen, the slippery surface of the spathe breaks down, allowing the insect to escape. As it flies away it bumps into the male flowers, picking up more pollen to take to the next plant of the same species that it comes to.

Two Specific Examples of Monoecious Reproduction

Philodendron auminatissimum: Sometimes the pollinating insect can outstay its welcome, perhaps damaging flowers or laying eggs. This Philodendron has overcome the problem by shrinking the spathe after the male flowers have become active. This means that the beetle must leave or become crushed.

Arum nigrum: This arum doesn’t trap visiting flies, it merely confuses them. The hood of the spathe hangs over the spadix, obscuring the  sunlight, and there are translucent marking in the base of the spathe. When a visiting fly tries to escape, it heads for the light, but this just guides it deeper into the spathe. This leads to panicked and more active movement, ensuring pollination.

Arum nigrum

Arum nigrum

Reproduction in Other Aroids

In dioecious aroids the female flowers are found on a different plant to the male flowers, so a genetic mix is guaranteed. Not many aroids are dioecious, but a few species of Arisaema are.

A few aroids are even paradioecious and change gender to suit circumstances.

Hermaphrodite aroids are similar to monoecious ones, the male and female parts on each flower mature at different times so self pollination cannot occur.



For the most part, arid aroids have not evolved the typical shrunken leaves and thickened cuticle of other desert plants. Instead they tend to grow under trees and bushes and at the base of rocks where a damp, shady microclimate allows them to survive. They have unusually lush foliage for arid plants. This would make them a target for being eaten, but they have dealt with this by producing harsh toxins and needles of calcium oxalate that pierce and poison the throats of animals. Animals know to stay well clear of aroids.

Some Examples

Dead Horse Arum

Heliocodicerous muscivorus

Heliocodicerous muscivorus: This is called the dead horse arum. It has an inflorescence 35cm long and wide. It grows in the shelter of rocks on a few islands on the Mediterranean. It is pollinated by either flies or beetles and grows where sea birds have their colonies at nesting time. Sea birds live in a mess of rotting fish and eggs, dead chicks and excrement, which attracts the flies/beetles. The arum must then compete with the smell of these, in order to attract those same insects for pollination. It mimics the dead not only in smell, but also by looking like the corpse of part of a horse, complete with tail. Visiting insects find themselves falling into where the ‘tail’ is and becoming trapped by the slippery walls. Many insects lay their eggs inside, although any maggots that hatch will likely starve to death. The insects are held for two to three days and are fed by nectar.

Note: It’s worth looking at photos of the dead horse arum, my painting doesn’t really do it justice.

Sauromatum venosum: This is the called the voodoo lily because it has the ability to flower without soil or water, using only the energy stored as starch in the corm. It smells rotten.

Stylochaeton lancifolius: This aroid has flowers and fruits half buried in the ground. I have been unable to find information about why this is. My suspicions are:

  1.  It is pollinated by animals that are close to the ground. This can be seen in Aspidistra flowers, pollinated by slugs and snails. The flowers grow on the ground, under the leaves.
  2. Being submerged provides a little protection, even if eaten or stepped on, the Stylochaeton still has half a flower remaining.
  3. The fruits are eaten by something small. Having eaten the fruit, the seeds can be dispersed in the faeces.
Stylochaeton lancifolia

Stylochaeton lancifolia



Rainforests are dense, shady, and teeming with aggressive life. Animals, plants, fungi and bacteria are locked in a constant arms race. Consequently aroids have developed strong poisons, shiny leaves and the ability to climb to cope with some of these problems. In the tropics, latitudinal diversity (a wider variety of organisms that occurs close to the equator) means that it may be many miles through dense forest between plants of the same species. For this reason, aroids use very strong, and often unpleasant, smells to attract the right kind of insect.

A tropical rainforest has distinct layers and aroids grow in each of these. There are terrestrial aroids growing in the ground and epiphytic ones that climb into the canopy.

Climbers and epiphytes have only aerial, adventitious roots. There are two types: those that are sensitive to light and make for dark crevices where they can grip, and those that are sensitive to gravity and hang down from the plant in order to soak up rain and humidity.

Terrestrial Examples

Deiffenbachia grows in the Americas, while Aglaonema is native to Asia, they are both highly variable, but virtually indistinguishable from one another. This is an example of convergent evolution. Both contain toxins as a defence; Deiffenbachia is commonly known as dumb cane, because the if eaten, it causes the throat to swell, so that speech is impossible.

Ag 2

Aglaonema and Deiffenbachia – both highly variable, but in similar ways


Amorphophallus: This is a genus of tropical and subtropical aroids, native to Asia, Africa and Australasia. They attract flies and beetles by giving off the smell of rotting meat. Unusually, Amorphophallus species only put out one leaf or one inflorescence at a time, one a year. The single leaf is highly divided.


Some Amorphophallus inflorescences


Single, highly divided leaf of Amorphophallus

Some species in this genus also have white patches on the stem, these are to mimic lichen growing on trees and serve to protect them from stampeding elephants. When tramping through the jungle elephants have learnt to avoid trees, which are usually covered in lichen. Amorphophallus would be very easily damaged by an elephant, so by looking a bit more like a tree they can fool the elephant into avoiding them.


Lichen mimicking stem

Epiphytic Examples



Monstera: These are one of the few plants to have holes in their leaves. Recent research shows that leaves with holes benefit in shady areas because the light coming through the trees is often dappled. By having holes in their leaves, Monstera cover a larger area with the same amount of leaf (so the same amount of energy used to make it) as a smaller leaf without holes. This allows the plant to take advantage of any sunlight that gets through the canopy.

Anthurium punctatum: This is an aroid from Ecuador. It has formed a symbiotic relationship with ants. It has nectaries away from the flowers because it is not trying to attract pollinators, but protectors. The ants set up home in the Anthurium and guard it from animals and insects that may eat it. However, in this Anthurium the ants are particularly aggressive and keep away pollinators also. The ants also secrete an antibiotic substance called myrmiacin, which is antibiotic and protects the ants from moulds and bacteria that might cause disease. However, this substance prevents pollen tube formation needed for the plant to be fertilised. These two barriers to pollination mean that the species can only propagate itself vegetatively.

Philodendron: This is a diverse genus. Plants can be epiphytic, hemiephytic or (occasionally) terrestrial. Hemiepiphytic means that the plant spends part of its life-cycle as an epiphyte (in the air). It may start off on the ground and then wind its way up a tree, then let its original roots die back. Or it may start as a seedling in the branches of a tree and a root will trail its way to the ground.

Philodendron bipinnatifidum

Philodendron bipinnatifidum

Temperate Woodland

Arisarum proboscideum

Arisarum proboscideum

Arisarum proboscideum: aka the mouse plant. This is a woodland aroid, native to Spain and Italy. It has flowers like little mice. The ‘tails’ of these give off a mushroomy odor, that attract fungus gnats for pollination. The flowers have a spongy white appendage inside the spadix that looks like a mushroom to complete the deception. Fungus gnats often lay their eggs in the flowers, although the maggots won’t live to adulthood.


As I have blogged before, plants never evolved much in water. This means that all aquatic plants have evolved on land and then evolved again to cope with life in water. Some problems faced are – damage to flowers and leaves due to water currents, lack of access to pollinators, water blocking out light, lack of oxygen (leading to rotting roots), and the heaviness of water (800 times as dense as air) putting pressure on foliage.

Some solutions to problems:

  • Aerenchyma:  these are gas filled cavities that improve buoyancy and oxygenation.
  • Fish shaped foliage: these offer less resistance to water currents, so less damage occurs.
  • Larger surface area in relation to volume: ie filmy leaves. This increases photosynthesis  eg Cryptocoryne
  • Roots: These are not needed to transport water, since it can be taken in by all parts of the plant. However, roots are used to anchor the plant and stopped it being carried away by currents. eg Jasarum steyermarkii
  • Reproduction: Many aquatic aroids find it easier to spread vegetatively rather than by flowering, in order to avoid flowering problems.

An Example

Pistia stratiotes 2.JPG

Pistia stratiotes: This is the only floating aquatic aroid, growing in swampy deltas in India and West Africa. It is adapted to staying still in fast moving currents, and has found the balance between sinking and blowing away.  The inner tissues have aerenchyma and the outer surfaces are ridged, velvety and with dense covering of hairs. This makes it unable to sink, and water repellent. Feathery roots act as an anchor. It has tiny flowers in a protective hairy spathe.

Pistias form a dense mat on the surface of the water, and can create mats of 15m wide. This makes Pistia something of a weed, causing problems to the ecosystem because the water underneath is deprived of light.

However, Pistia is not only harmful, some ecological benefits:

  • The darkness caused by the Pistia mats has led to the evolution of blind elephantnose fish, which live beneath the mats. They hunt by electricity and have well developed brains and learning abilities.
  • Birds and animals often make the floating island their home.
  • Pistia can purify stagnant water.


Note: outdoor photos are mostly taken in Ecuador and indoor photos mostly from Wisley Gardens.



  1. Understand the historical development of garden design styles.

    1.1 Describe representative characteristics of the following garden design styles: Moghul, Moorish, Medieval, Renaissance (Italian, French and Dutch), English Landscape, Victorian, Edwardian, Japanese, Modernist, Contemporary.





(Afghanistan, Pakistan, India)

 C 16-19th

Formal, symmetrical, water – channels and pools, terraces, avenues of Cyprus, scented flowers. 4 types: palace, tomb, waterfront and terrace.

Taj Mahal, Agra


(Spain, Portugal, S. Italy, France)

 C 8-15th

Water and shade used to cool gardens. Gardens divided into four. Fountains and ponds, ceramic tiles, carved stones, hedges, containers, fragrant flowers. Cyprus, Sycamore and Citrus.

Maria Luisa Park, Seville


 C 12-15th

 Food production – orchards, herbs, medicines and vegetables. Walls, fragrance, wells, turf seats, arbours, grassed dancing, mounts to view. Pleached limes.

Alfriston Clergy House



Parterres. Dramatic views, spectacular fountains and cascades, woodland, orchards, herbs, levels. Inspired by Romans and ancient mythology.

Villa Lante



Parterres. Acute angles, ornate statuary, fountains, rigid symmetry, canals, views, focal points and cascades at the end of every vista. Terraces and grottoes.

Luxembourg Gardens



Parterres. Rectangular spaces divided to squares, leafy walks, arbours, fountains, mazes, bulbs. Buxus hedges. Helianthus, Papaver and Rosa.



Idealised version of nature, inspired by paintings. Classical. Lakes, rolling lawn, grove of trees, temples, Gothic ruins.

William Kent, Lancelot Capability Brown



Glasshouses and conservatories leading to overwintered tender plants. Carpet bedding, new plants from abroad – Dahlia, Aster, Impomea, Zinnia. rockeries, parterres, arboretum.

Sir Joseph Paxton, Cragside, Northumberland



Hedges, Terraces, sunken, pergolas, cottage garden styles

William Robinson, Lutyens +Gertrude Jekyll, Reginald Bloomfeld



Borrowed scenes, asymmetry, moss gardens, bonsai, miniature landscapes, fish, cloud pruning



 1800  popular 1930

Water, geometric, asymmetry, crisp + clean, planting in one part. large horizontal landscaping – stone, wood, concrete, cement, plastic.


Last ten years

Grasses, sunken LED lighting, simple, bold, architectural planting, repetition of plants, hard landscaping innovative and central to design, natural looking materials eg distressed metals, stone, sustainable materials.

Difference between Modernist and contemporary styles

Firstly, Modernism is a specific movement that started in the 1800s whereas contemporary is simply what is happening now. Modernism occurred at a time of the Industrial Revolution when form followed function – how well it worked mattered more than how it looked. As a result the garden style was simple with no fancy details. Contemporary tends to use a similar ethos (simplicity, functionality) but it also tends to reflect our recent interest in sustainability using recycled materials more. Plus it is influenced by our desire for more natural looking settings, so functional metal is a common material for both Modernist and contemporary, but distressed metal looks more natural and so features only in contemporary. Recent advances in LED lighting are also made use of in contemporary styles. Contemporary gardens often follow current fashions such as willow fencing, decking or insect habitat boxes.

  1.  Understand how to conduct a site appraisal and interpret the results

    2.1 State the main factors to be assessed for an overall site appraisal.

    2.2 Review the advantages and limitations which site factors may impose on garden planning and layout, to include accessibility for disabled users.

Information about the site to be collected at site appraisal and advantages and limitations:

Microclimate – caused by walls, buildings and plants altering the climate over a tiny area. Can provide planting opportunities (eg tender planting in sheltered corners) or planting restrictions (limited planting possible at the base of a Taxus hedge). Hard landscaping is also affected by microclimate (eg moss and algae forming on decking in shady areas).

Orientation – The direction the garden faces in affecting sun, shade and wind  (north=cold and shady, south=warm and sunny) in turn affecting the positioning of features (walls shouldn’t block sun, patios may need shade/sun) and plants (shade loving, tender plants needing specific aspect). Similar to microclimate.

Access – to garden from road, from house to garden and around garden. Relevant for both work in the garden and garden users. Disabled users – question whether existing hard landscaping is safe and convenient for use, whether ramps, handrails and so on are adequate. Children – are there safety risks, such as ponds? For gardeners and landscapers – will work be limited or more costly due to difficult access?

Climate – the long term weather patterns of an area,  includes prevailing wind (from somewhere warm or cold), temperature (varies according to urban/rural setting, closeness to sea and topography) and average rainfall. Both plants and features are affected by climate . Similar to orientation and microclimate, important to think about what plants will thrive best, what hard landscaping materials will need the least maintenance in that climate and about how the garden owners will want to enjoy the garden – eg a cold, wet climate is not ideal for an outdoor swimming pool.

Contours – the varying heights within a garden. Levelling may be necessary for patios or to get rid of frost pockets. Drainage and erosion may be a problem. Levels can add interest. (see next blog for information about how to ascertain levels). Disabled users may have particular problems with slopes or stairs. Steep slopes can limit building access and maintenance (eg lawnmowers struggle with slopes). Sunken areas and steps can create views and interest.

Existing features – their condition, what needs to be kept, existing colour scheme and style. See access. Particular features may be used to build a design style around – for example a beautiful Victorian wall can inspire a Victorian garden.

Services – drains, electricity, water pipes. Overhead and underground services to be recorded. Overhead power lines may restrict use of machinery, underground pipes may be a problem when laying drainage or building swimming pools.

Soil – pH, textures, structure, top soil depth, soil pans, drainage, nutrients, rubble and contamination content. Planting might be limited eg only calcifuges or bog plants. Topsoil may need to be imported.

Existing vegetation – their condition and interest, privacy and wildlife to be considered, Tree Preservation Orders. With TPOs it may not be possible to cut down a large, imposing tree, birds nesting may limit timing of hedge cutting/removal. For disabled users – consider whether soft landscaping is easy to care for, for children – whether existing plants are harmful – if ingested, toxic sap (eg Euphorbia)

Dimensions – size and shape of the garden affects types of features and plants used. Designing for awkward shapes can lead to innovative use of hard/soft landscaping. Size and shape of garden affect design (eg a narrow garden may use diagonal patterns, lawn size and hard landscaping to increase feeling of width, a small garden needs hard and soft landscaping in proportion to the garden size, a large garden can be divided into different ‘rooms’ and styles). Opportunity to use unusual shapes to create interest or use landscaping to make an uninteresting shape more unusual.

Legislation – TPOs, conservation areas, planning regulations, boundaries (height of walls etc), Hedgerow Regulations all can restrict what change are possible. See existing vegetation.

Exposure – how much a garden is open to the elements and affected by wind or salt in coastal gardens. Relevant to plant selection (certain plants survive better in exposed areas) and seating (people don’t usually want to sit in a high wind). Wind breaks (hedges or walls) can be put into design. In a sheltered garden tender plants may be grown and in an exposed garden hardy plants will be needed.

Altitude – affects the range of plants grown, higher altitude=low temperature and more exposed. See Exposure.

Views – what surrounds the garden. Borrowed views can be used to create a larger garden or it may be necessary to hide ugly views by screening.

External factors – includes views, causes of microclimate (eg large buildings = shade), wildlife. See views, climate, legislation and microclimate.

  1. Know how to develop a client brief

    3.1 Identify the information which needs to be gathered from the client, to include: likes and dislikes, aspirations, functional requirements (e.g. utility, play area for children, restricted mobility), ornamentation, relaxation, entertaining or food production, degree of maintenance and budget.

Questions that can be asked to clients (taken from a number of client questionnaires on the internet, garden design websites are good for this).

What are your personal preferences?

  • What do you like and dislike about your garden?
  • What colours do you like?
  • Any specific styles you like (eg Alpine or formal)?
  • Any specific plants you would like?

What mood would you like for your garden (mark all appropriate)?

  • Calming
  • Private
  • Fragrant
  • Colourful
  • Tropical
  • Practical
  • Wild

What do you use your garden for?

  • Do you like entertaining?
  • Have any sports hobbies (football, swimming)?
  • What time of the year will you most use your garden?
  • What time of day?

Which features would you like (mark all appropriate)?

  • Water feature
  • Vegetable patch
  • Fruit
  • Herbs
  • BBQ
  • Lighting
  • Children’s play area
  • Parking
  • Compost

Do you like gardening?

  • How much time will you be able to spend on the garden a week?
  • Will you be hiring a gardener?
  • Any specific jobs you hate (eg Mowing the lawn, raking leaves)?

Who is the garden for?

  • Do you have children or pets?
  • Anyone with any disabilities or special needs to use the garden?

Are there any specific problems you would like solved (mark all appropriate)?

  • Bad drainage
  • Lack of privacy
  • Noise
  • Unpleasant views
  • Pests (badgers, rats and rabbits)

What is your budget?

3.2 Describe how to record relevant data using a client questionnaire, audio and visual methods.

Collect information from client by:

  • Using a questionnaire (may be online or in person)
  • Email
  • Using a digital audio recorder
  • Taking photographs (if an iPad is used, redesigning can be put straight onto a photograph)
  • Sketches

This leads to a Concept Plan that shows problems and applies solutions. In addition to this the site appraisal provides information on the dimensions and details of the garden which is used to draw up the various design plans.

4. Know a range of basic survey techniques

4.1 Describe the linear surveying of a site using appropriate equipment to include tapes and automatic levels.


  • Linear surveying – Measuring distances between points on parts of the earth’s surface. In a garden survey this would include measuring the size and shape of hard landscaping (eg walls and fences), boundaries and plants (eg trees) that are to be kept in the design.
  • Datum – line or level surface to which all heights are referred.
  • Reduced level – level above or below the datum point.
  • Line of collimation – line of sight horizontal to the ground.


  • Tapes – measuring tapes. Lots of clear info here – Linear Measurement Taping.
  • Automatic levels – a device mounted on a tripod used to measure levels. Used with a staff.
  • Dumpy level – similar to automatic level, slightly different mechanism Wikipedia page.
  • Theodolite – a precision instrument for measuring angles in horizontal and vertical planes.
  • Electronic distance measurement device (EDM) – a hand tool that accurately measures distance by sending a pulse of light to a surface.


  • Triangulation – using two known points to determine the position of a third, unknown point by measuring the angles and distance.
  • Trilateration – using the geometry of circles, squares and triangles to determine, record and map the position of features.
  • Offsets – marking the position of a number of features, measured from a straight line (a measuring tape).
  • Clock method – mark central point and walk round in a circle recording features.
  • 3:4:5 Triangle – used to find a right angle, useful for measuring, especially offsets. Beautifully simple explanation here.

Excellent website for how to conduct a linear survey, how to set up levels and how to produce contours and longitudinal sections here – Linear survey.

 4.2 Describe the surveying of a site to record variation in levels using automatic level and staff.


4.3 Interpret survey measurements from standard documentation.

4.4 Produce scale drawings using survey data, including the correct use of graphic symbols, scale and nomenclature.

Types of Plan

Designer’s Plans

  • Location plan (marking where site is on a map)
  • Zone map (shows soil type, microclimate etc)
  • Site survey
  • Concept plan (shows problems and solutions)

Plans for Client

  • Sketch design
  • Final design
  • Sketches, elevations and perspective drawings

Plans for Construction

  • Construction details
  • Hard works layout plan (BSI graphics, structures and levels)
  • Services
  • Planting plan
  • Setting out plan (dimensions, measurements and offsets)


  • Scale ruler
  • HB and 2H pencils
  • Eraser
  • French curves
  • Compass
  • Drafting pen


How to Draw a Garden Plan

Two websites from which you can download (for free) garden design symbols, or just see the symbols and get an idea of what there is:

5. Understand how site characteristics may influence garden design 

5.1 Explain the influence of the following on a choice of design : altitude, orientation, aspect, changes in level, pollution, soil type, soil depth, soil pH, soil water content, views, screening, degree of exposure or shade, microclimate.

5.2 Explain how a given design may be used to enhance the attributes and offset the limitations imposed by the site.

(note: these questions cross over with 2.1 and 2.2 covered in the previous blog, however, I’ve elaborated on them here.)


Problems with high altitude:

  • Much shorter growing season.
  • May have midsummer hail and frost.
  • Intense sun, high winds and drought.
  • Rocky alkaline soils or forest-shaded acidic soils.
  • May be nutrient deficiency due to leaching.
  • Heat is slower to build and quicker to dissipate.

Solutions to problems:

  • Alpine plants
  • Terracing
  • Mulching with organic matter to improve soil


Design adaptations for South facing gardens (sunny):

  • Sun loving plants – Mediterranean or succulent – styles led by planting
  • Pale hard landscaping
  • Providing shaded areas for seating
  • Irrigation for plants
  • Water features can provide sense of cool

Design adaptations for North facing gardens (shady):

  • Shade loving plants
  • Problems with growing grass – keep lawns small or use a moss lawn
  • Algae forms on decking in the shade, use brick or stone
  • Use mirrors and reflective surfaces to increase light
  • Use pale flowers and bright colours
  • Position seated areas to make the most of the sun
  • Avoid shading more areas with large trees or high walls

East facing gardens have early morning sun that can cause frost damage on some plants, to avoid this, position variegated or tender plants carefully to avoid early morning sun. Camellias are especially susceptible.


Note: Orientation and aspect are often considered to be the same thing, but aspect can also include shade and shelter (eg a sheltered aspect). Sheltered gardens often suffer from shade, this is covered under North facing gardens above.

Changes in Level

Ways to use existing levels or create changes in level:

  • Steps
  • Sunken areas
  • Raised beds
  • Sunken paths surrounded by walled beds
  • Mediterranean style gardens with split level patios.
  • Tiered multilevel gardens
  • Rockeries
  • Waterfalls

Problems with slopes, solutions:


Different types of pollution and solutions:

  • Rain – a rain garden – a planted depression that absorbs water and allows it to flow into the ground rather than storm drains.
  • Noise – walls and thick growing trees or shrubs block sound, running water features and wind chimes cover sound.

Soil Type

Factors to consider and solutions:

  • Soil texture – eg sandy or clay. Affects what plants can be grown and what kind of drainage can be used. Clay soils may benefit from raised beds, sandy from incorporated organic matter.
  • Soil structure – improved by adding organic matter, maybe add a compost bin to a garden with bad soil structure.
  • Topsoil depth – plant choice is limited by shallow soils. Raised beds can solve this.

Soil pH

Acid loving plants – Camellia, Calluna, Kalmia, Erica, Cornus, Acer, Abies

Alkaline loving plants – Geranium, Aucuba, Lavandula, Delphinium, Crataegus

Note: outcome 3 of unit 2 will cover plants for situations more fully

Soil water content

  • Make use of wet gardens with bog plants or ponds
  • Make use of dry gardens with succulents
  • Solve drainage problems with a swale, pipe drainage or a soakaway
  • Solve irrigation problems with a leaky hose


Borrow views from neighbouring gardens and landscapes, creating a connection between plants inside and outside the garden. Hide ugly views with screening – fences, climbers, trees; or distractions – brightly coloured foliage or landscaping that draw the eye.

Screening and exposure

Types of screening:

  • Hedging – Taxus baccata, Ilex aquifolium, Ligustrum ovafolium
  • Evergreen climbers – Trachelospermum jasminoides and Clematis armandii
  • Walls – brick, cement blocks and dry stone walls
  • Fences – woven willow, featherboard and panel fencing
  • Trees – Arbutus unedo and Eucalyptus gunnii

Exposed gardens, problems and solutions:

  • Plants exposed to the elements (harsh winds, sea spray) – hardy plants, thick hedges, walls.
  • Soil erosion – see Changes in Level.


This is linked with aspect and orientation. A garden can contain many subtle (or not so subtle) differences in moisture, shade and shelter and so solutions to those types of climates can also apply on a small scale to the microclimates in a garden.

6. Understand the principles and elements of design

6.1 Explain the principles and elements of design: to include movement, rhythm, scale balance, form, texture, space, colour , proportion, harmony, unity, symmetry, and asymmetry, focal point, borrowed landscape.

6.2 Describe examples of the application of the elements in 6.1 to the design process.


How the eye moves around the garden, some shapes, patterns, paths and lines create movement. Also physical movement – water, plants.

  • Curves create gentle, restful movement
  • Angles give a sense of restlessness
  • An off-centre focal point can create a sense of movement and dynamism, and invites curiosity
  • See also Form
  • Water in water feature is constantly moving
  • Grasses move in the wind

An article about rhythm and movement

Example: A curving, winding path edged with long grasses (Miscanthus sinensis) would create a soothing, but constant sense of movement. See Piet Oudolf designs.


Using repetition to connect areas of the garden and create unity, also connected to movement, since rhythm is found in the pattern of visual movement.

  • Repeated features – flower colours, hard landscaping, clipped topiary
  • Repeated styles – sweeping lines, geometric patterns, interlocking features
  • Repeated colours – pastels, primary colours, contrasting colours, deep reds and grey foliage

Example: A set of three, large, terracotta pots on a wall filled with identical purple Lavandula angustifolia ‘Hidcote’ bushes, edged with black Ophiopogon planiscapus ‘Nigrescens’. This purple and black colour combination can also be used elsewhere in the garden and the terracotta colour can be repeated in red brickwork.


Scale refers to the size of the garden in comparison to non–garden objects (as oppposed to Proportion which refers to the size of garden components in comparison with each other), for example:

  • Size of humans in relation to garden (eg paths)
  • Size of garden in relation to house
  • Size of surroundings (eg trees and buildings outside the garden) in relation to garden

Example: A garden surrounded by a wood with large trees needs at least one large tree inside the garden to give a sense of scale. For example an oak woodland would benefit from three Quercus robur inside the garden, spaced to connect the whole garden with the view.


Balance is an even distribution of visual weight – weight created by colour, colour brightness, landscaping or plant size. Balance is like a very loose symmetry, for symmetry if there is a statue on one side of the garden there should be a statue on the other, whereas a statue in one part of the garden can be balanced with a pergola in another part.

  • No single object should dominate excessively

Example: Three Acer palmatum ‘Bloodgood’s ( that turn bright red in the autumn) are spaced apart on one side of the garden, and can be balanced with a single, larger Cotinus coggygria ‘Royal Purple’, (that also turns red in the autumn) on the other side of the garden.


Form is the habit and shape of plants, different plant shapes create interest, harmony and/or movement

  • Fastigiate form creates dynamic effect.
  • Combine shapes, eg transparent sprays in front of solid colour, weeping shapes with upright.
  • Forms – fastigiate, weeping, columnar, oval, round, spreading, pyramidal.

Example: Closely pruned Buxus domes contrast with upright Euphorbias and sprays of fine textured grasses (see below). There is enough enough interest to make this an enjoyable garden to look at, but enough repetition to unify the garden.

Telegraph Garden at Chelsea

Telegraph Garden at Chelsea


Texture is determined by leaf size, by light reflected from leaf surface or by comparative detail on hard landscaping. Combined with colour and form, plants can be put together in a way that is striking or subtle. Most designs will use a combination of striking accents in a subtle whole – all subtle can be dull, all striking is exhausting.

  • Light filtering translucence of thin leaves contrasts with reflected light of small leathery leaves.
  • Textures can be fine (small leaves eg Buxus sempervirens), medium or coarse (large leaves, eg Musa basjoo).
  • Mixing textures creates interest, however it’s not good to position fine with coarse, instead use fine with medium, medium with coarse.

Example: (see below) The large variegated leaves of Hosta with smaller, divided, purple leaves of Heuchera.

Chelsea Flow Show

Chelsea Flow Show

Example: Spiky Eryngium giganteum with soft Salvia argentea and fine Stipa (picture).


Space can refer generally to the area to be designed or more specifically to how open an area is.

  • Balancing privacy and shelter with a more open sense of space.
  • Using partially visible areas to create interest– Hahas, large circular holes in walls, hedges, walls.
  • Restraint – reveal a little at a time – eg series of focal points gradually revealed.
  • Different heights can be blocked from view – using hedges or a canopy of trees.


  • Reds and orange brings warmth and vitality
  • Blues pinks and whites are subdued and cooling, add depth
  • Colours can be used to bring unity – repeating certain colours in hard landscaping and planting
  • Green is used as a foil in garden design, a neutral colour
  • Too much colour variety can be exhausting
  • Use different seasons to explore different colour palettes

ColoursExample: A herbaceous bed at Kew Gardens (see below) uses harmonious colours, reds to yellows.

Kew Gardens

Kew Gardens


Proportion refers to the relative size of parts within a whole, how the size of garden components relate to one another.

  • The divine proportion (golden ratio) is 1:1.618, using this as width to length is satisfying to look at.
  • Have a third hard landscaping to two thirds of soft (some styles do not follow this).

Example: Every design on this siteshows very pleasing proportion; paths, pots, hedges and plants all fit together in a satisfying way where no part feels out of place or wrongly sized.


This incorporates balance and unity throughout a design so that all parts of the landscape are adapted to one another, forming an agreeable whole.

  • May be colour harmony – using colours that work well together, either complimenting or contrasting.
  • Harmony does not need to be safe and conventional : unconventional, innovative designs can still be harmonious.

Example: Using a limited colour palette, such as burgundy and whites (see below), the fluid planting, and rock and cobble stone hard landscaping create a harmonious whole.

Vital Earth Nightsky at Chelsea

Vital Earth Nightsky at Chelsea


A thread or theme running through the garden that connects everything together. May be:

  • Colour (see colour, can be in both hard and soft landscaping)
  • Period of history (eg Victorian, Landscape)
  • Style (eg Mediterranean, Japanese)
  • Repeated hard or soft landscaping (eg Buxus hedging)

Symmetry and Asymmetry

The use of mirror image with identical hard/soft landscaping either side of an imaginary line (or not identical for asymmetry).

  • An asymmetrical design can use the golden ratio to establish balance.
  • Symmetrical designs use parterres (four way symmetry).
  • Bilateral symmetry – mirror image split down the middle, eg fastigiate Populus nigra and domed Buxus in a pattern of bilateral symmetry or a Buxus parterre.
  • Radial symmetry – like a wheel with spokes.
  • Approximate symmetry – similar objects and shapes either side of a line, not exact, varying in pattern etc.

Focal Point

An object of interest that draws the eye

  • Water features
  • Statues
  • An architectural plant
  • Hard landscaping
  • It’s important not to over use focal points so a garden becomes cluttered.
  • Remember balance when positioning them (or use symmetry).
  • Focal points work well when partially seen, at the end of a journey through the garden, or when partially obscured to create interest.
Water Feature Focal Point

Water Feature Focal Point

Statue Focal Points by David Meredith

Statue Focal Points by David Meredith

Some more examples of focal points here, here and here.

Borrowed Landscape

Using an attractive view or plant (usually a tree) outside the garden. This can be done by:

A couple of very good books that define and describe concepts such as unity and harmony, and talk about plant combinations, using texture, colour and form: