Willem says: 'The Phyto-Philes are for plant lovers of every size and shape, colour and flavour. As with my Colours of Wildlife column, I'll be featuring one species per article, illustrated with sketches, paintings, and/or photos. Over time I hope to be showcasing the amazing diversity of weird and wonderful plants that occur in South Africa, while also from time to time looking at the flora of other countries. While featuring many spectacular species, I'll not be neglecting the smaller, more humble kinds that are nevertheless fascinating in their own right.'

Bark, Bite and More

In the wild, the star chestnut grows as a low but spreading tree, often with a very short and thick trunk. In fact, the trunk usually starts branching just a few feet, or sometimes just a few inches, above the ground. The branches themselves are more slender. But most striking about this tree is its bark! The bark flakes in several layers; each layer has a different colour, so you see patches of green, orange, yellow, creamy-white and wine red; these can be differently apportioned in different individual trees, or at different times of the year, with different colours being dominant. Big trees with particularly fat trunks can give a marvelous, sometimes even other-worldly display.

I include two photos here of trees growing in the wild. You can get there an idea of the flakey bark, although these specimens are more impressive in reality than on photos. They grow in dense, dry bush and the intensity of the sun together with the shadows of surrounding vegetation here 'wash out' much of the colour, which shows up much more vividly to the naked eye.

Other than the fat trunk and the bark, this tree is distinguished by small, soft, delicate leaves. Here is a scan of one growing in my garden (and with a couple of flowers as well). These leaves van vary from roundish to three-pointed as here. They rarely exceed 5 cm/2" in length. In the wild, the leaves are rarely conspicuous, indeed the tree stands for half the year or more without any leaves. In my garden they are more lush, as you can see in the photo. This one stands just over a metre in height. But in the wild, trees can respond with good leaf growth in seasons of abundant rainfall.

As you can see, star chestnuts have very pretty and delicate flowers as well. These appear on the branches before the leaves do, at the end of winter to the beginning of spring, sometimes into summer. They are yellow with thin red streaks running lengthwise along the inner surface. They are pollinated by insects which results in the formation of the weird fruits for which the species gets its common name! True chestnuts have fruit capsules (actually called 'cupules') that split open lengthwise to expose and release the nuts, which are the actual fruits. In the star chestnut the fruit is in the shape of three to five pointed capsules, each up to 7.5 cm/3" long, joined together in a radiating star shape; these also split open lengthwise to release the seeds. But the seeds in this case are seeds, not nuts, and they are black, much smaller than real chestnuts, with a small whitish knob called an aril at the one end. These seeds are edible, but I haven't eaten them yet so can't tell you how they taste!

Growing the star chestnut involves removing the seeds from the star-like fruit capsules. This can be a painful process! There are sharp, tough, stinging hairs in the capsule along the margin of the opening around the seeds. These will lodge in your fingers and cause irritation lasting for hours. So this tree's bite is definitely worse than its bark! But after you've removed the seeds, you can use the star-like capsules. They're intriguing looking and are often used as ornaments for desks or for Christmas trees! They're sometimes painted, but look interesting enough as they are.

The God of Dung?!

These trees are just one species in the lage genus Sterculia, which is found in Africa and Asia. Many species are ornamental and grown in gardens all over the world; a few species become huge trees. They're generally known as tropical chestnuts, although they are not closely related to chestnuts at all. In fact they are members of the Malvaceae, the Mallow family, which includes popular garden plants such as the Hibiscus flowers, crop plants like cotton, okra and cocoa, and many tropical trees including Baobabs. The genus as a whole is named for Sterculius, the Roman god of manure (why would they have a god for that?) because some species have rather unpleasant-smelling flowers. The star chestnut itself has a species name commemorating Archdeacon F. A. Rogers, a missionary who collected a great many plants during his travels. Sterculia trees exude a gum that has use as an emulsifier and thickener in foods, and also as a laxative and denture adhesive. The flaking bark of the star chestnut can be used as a source of fiber for making rope or coarse thread.

Cultivation

It's not hard to grow star chestnuts. The irritation of removing the seeds from the pods is not too bad. Seeds can be soaked in water prior to sowing to enhance germination, but I've not found this necessary and have had great results just planting them in bags. I usually do this at the start of the rain season and then let the rain moisten them; they germinate very well like this. The little trees grow fairly slowly, but attain a nice shape and fat little trunks early on. It takes a few years before the bark starts flaking. They start flowering at around three years of age and mine flower very nicely in their little bags. They're not yet setting much seed, though … it might be that the right pollinating insects are rare here. The young trees need well-draining soil and are sensitive to overwatering.

Star chestnuts are best grown in hot and not-too-wet regions. They definitely need a dry winter in which to rest, and one with only very light frost. This tree usually only grows to about 5 or 6 m/17'-20' in height, with a similar or slightly greater spread, and a trunk up to about 1m/3' thick at ground level. As such they are well suited to small gardens. They will look great on the sunny side (north in the southern hemisphere, south in the northern hemisphere) of a rock garden wedged between large rocks or boulders, as they often grow in the wild. This will also show off their fat trunks and colourfully peeling bark to advantage! But in colder or wetter climates this species can be grown as a house plant, in a sunny position, on a porch or verandah or on a windowsill. In a clay pot, they are less likely to rot from overwatering. The leaves and flowers being naturally small and the interesting, gnarly shape developing rapidly make this species very well suited for a bonsai.

Colours of Wildlife Archive

Willem

28.10.13 Front Page

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