Mysteries of the wonder crop

THIS week I am inspired by a blocked drainpipe. Happens a lot round here; a result of being fortunate enough to live in an old house with cast iron drainpipes surrounded by trees.

So far I have dismantled three wire coat hangers and tried a variety of sticks to push the blockage down and round the bends to absolutely no avail. Until yesterday, when I cut a stray immature bamboo shoot and found that it had the strength not to break as I forced it into the pipe but the flexibility to get round the corner and push out the mass of leaves.

Which made me think about bamboo itself, a plant that has a long history as a tool for humankind but also has something of a reputation.

Over the years I have heard or read snippets and stories about bamboo which have intrigued and excited me so I think it is time I scratched that bamboo itch once and for all. I use that phrase quite literally as a skin reaction to bamboo sap is relatively common!

At first, I planned to mostly talk about the ornamental varieties that are suitable for our gardens. Varieties like black stemmed Phyllostachys nigra are often used to provide some oriental elegance but bamboo comes with many caveats.

In effect there are two types of garden bamboo – ‘clump forming’ and ‘running’ and most books and websites talk about this rather than the decorative qualities. With good reason.

Running bamboo is an invasive beast, occasionally deliberately used for screening but more often accident- ally bought and regretted when it runs amok in both your border and your neighbour’s. An initial small clump may quickly start to throw out runners up to 10 feet away in every direction, unlike clump forming bamboos which expand only a few centimetres a year in a well behaved fashion and are much easier to deal with.

Many bamboo species are classified as ‘invasive species’ round the world although I noticed that in most cases sources of information , whilst quick to warn the unwary gardener, rarely list the species that cause all the problems or give us advice on suitable bamboo plants that won’t take over the world.

Once I started researching deeper, I found that bamboo is a fascinating botanical creature, a potential house guest carrying a suitcase full of astonishing facts, legends and stories.

Behind the dull, everyday garden canes we so happily use to hold up our tomatoes and hollyhocks lie a host of interesting facts.

So let’s start with the botanical basics. Bamboos are a large family of evergreen perennials belonging to the grass family, hence the hollow stems. Rather wonderfully they are split into three tribes (a genuine term of classification in botany) – herbaceous, temperate woody and tropical woody. So far so good. In this country we mostly grow the temperate woody species like Phyllostachys, but they are all imports.

In other parts of the world, though, there are hundreds of species, living everywhere from Mexico to sub-Saharan Africa as well as Asia, the area we most often associate with bamboo, not

Bamboo least because it is the favourite food of the Giant panda!

Fast growth is a characteristic often associated with bamboo.

Some species can grow nearly a metre in 24 hours; that’s about 1mm every 90 seconds, according to the Guinness Book of Records. Like couch grass, it relies on rhizomes to support this fantastic growth.

This phenomenon is dependent on soil and climate so it’s unlikely the bamboo in your garden will perform at quite this rate.

Nor is it likely to reach the huge heights that it is also known for. Whilst in the right conditions some species can grow to around 80m tall, in our gardens 4.5m is more likely.

The most intriguing botanical trick of bamboo, and still the least understood of its characteristics, is its flowering pattern.

Bamboo notoriously takes a long time to flower, and when it does all related plants will flower at the same time, even if not planted in the same area.

This mass flowering can have big economic consequences. It can take anything from 50 to 100 years for flowering to occur, the record. Wherever they are planted and whatever the conditions all related stock of this plant will flower simultaneously responding to an internal ‘alarm clock’ that remains a mystery, although interesting theories include ideas that revolve around lightning strikes, life cycle of rodents and other predators and my favourite, that bamboo flowering frequency is always a multiplication of a prime number.

What this actually means I have no idea, nor can I understand how this is possible, but I love the concept nevertheless. Bamboo maths. Wow!

What is more comprehensible is the result of this mass flowering.

The fruit produced, all at one time, can lead to a boom in rodent populations, which then go on to eat other foodstuffs, and harvests causing famines amongst humans as well as increasing the incidence of diseases.

Communities that rely heavily on it as a crop suffer tremendously especially since their main source of income will temporarily disappear.

Which leads me nicely onto the useful side of bamboo, the reason why communities around the world do rely on it as a crop despite its occasional strange behaviour.

It is a versatile self-sustaining raw material, used for scaffolding and building houses, as it is at least as strong as steel and certainly stronger than wood or brick.

It can also be used to make paper and pens, furniture, kitchen implements and weapons.

The young shoots are also a valuable food source, although toxic unless properly prepared, and feature in many Asian dishes.

Last but by no means least bamboo has a reputation as an ecological wondercrop and a more environmentally friendly alternative to imported cotton. Growing it is ecologically a good idea, it’s true.

Bamboo requires no pesticides, absorbs five times more carbon dioxide and produces 35% more oxygen than a similar group of trees and requires little water.

As a textile, though, things get a little messier. In most cases high levels of unpleasant chemicals are needed to turn bamboo into a fabric, making it not quite the eco-friendly alternative that it is often presented as.

The miles it has to travel too can be a real problem, negating any benefits.

In the meantime Happy Gardening!