Tree grapes
Created | Updated Dec 16, 2012
Tree Grapes
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.'
Today's article is about another weird plant species from Southern Africa: tree grapes! This particular species is Cyphostemma juttae. As you may gather from its name, it is a member of the Grape family, the Vitaceae. But it is very different from grapevines in appearance! This tree grape is a succulent, with a very fat trunk from which a few rather short, fat branches arise. They bear a crown of very thick, succulent and large leaves. The leaves are divided into three lobes, each lobe of which could be half a metre in length. The lobes have toothed margins that are often reddish in colour. The leaves are actually red when they first emerge in Spring, as you can see from my photo. They gradually turn green, the margins last of all. This species can reach a height of 4 m/13 ft, with a very thick trunk. Such a specimen would be incredibly impressive! But in gardens they rarely become that big; a more typical height is a trunk of about a metre tall with the leaves adding a bit to that. My specimens are about that size. They are still dominated by the huge leaves although their trunks are already nice and fat! My painting shows a much larger specimen with a pronounced branched and well-developed trunk. In Afrikaans they are known as ‘kobas', ‘basterkobas', and ‘droog-my-keel' (‘parch-my-throat') for the effects of eating the fruit – read on!
These plants just have so much character! Although they grow fairly slowly they are interesting right from the start with their huge, succulent leaves. The trunk will fatten up quite rapidly, but lengthens and branches more slowly. When a substantial trunk size is reached, the bark will start flaking of in large, papery pieces. The flaking bark is yellowish, with a greenish underbark. Its light colouration helps reflect sunlight in the very hot regions where they grow. They are easy to transplant and can first be kept in pots, then later transferred to open beds. This is only feasible in suitable climates, though. These tree grapes cannot handle anything but light frosts, and also don't want soggy soil. Although ideally they prefer to have a dry winter in which to rest, they can adapt to year-round or even Winter rainfall provided the climate is not too wet. Elsewhere they can be kept in hothouses or in pots on a sunny windowsill, at least while they're still small! I feel this plant must be given enough room; in a climate that's anywhere close to favourable it can become a very big and impressive specimen. They prefer a sunny position in well-draining and fertile soil, and in the growing season, moderate watering... a week or two between waterings should work well.
The tree grapes bear grape-like fruit. These originate on branched inflorescences that emerge with the new leaves in Spring. The flowers are small and inconspicuous, but nevertheless I see mine attracting lots of bees, wasps and other insects. The inflorescence stalks are reddish, and the berries, when they develop, turn red as well, for a colourful display amidst the leaves. But don't try eating the berries! Although they resemble grapes they are quite toxic. There is actually not much of a danger of getting poisoned by eating them, since they will scorch your mouth and throat to the point of agony well before you managed to ingest a lethal dose. The poison in fact is strong enough to burn one's fingers … as I experienced when I first tried extracting the seeds from the fruit. My fingers were burning for days afterwards! I've subsequently found it helps to let the fruit dry out till they are almost raisin-like; then the dry flesh can be removed more easily from around the seeds without burning the fingers. I am still wondering what eats these fruits in Nature; they are so conspicuous, surely they must attract something that is immune to them? And the flesh must be removed before the seeds can germinate. They should be planted at the start of Spring and germinate erratically … some germinate quickly but some may be reluctant, and actually take until the next year's Spring to germinate!
The leaves emerge at Spring, attain maximum size in the middle of Summer, and are shed at the onset of Winter. Don't think your plant has died when they curl up and whither! For neatness' sakes you can break or prune them off at this point. This plant will often shed young twigs along with its leaves. You might try planting these (after removing the leaves) in well-draining and fertile soil – sometimes they strike root and grow!
There are a few more species of tree grape occurring in the country of Namibia, mostly along the escarpment that divides the almost waterless Namib Desert along the coast from the somewhat less arid woodlands and bush of the interior. The species Cyphostemma currorii is the largest, reaching seven metres in height and a trunk that can be over a metre in diameter! Other species like Cyphostemma bainesii and Cyphostemma uter are also tree- or shrublike in form, but much smaller. These can all be termed ‘tree grapes' though.
The genus name ‘Cyphostemma' means ‘humped garland', maybe referring to the curved stalks on which the flowers and fruits are borne. The species name ‘juttae' refers to Jutta Dinter, who with her husband Kurt explored much of the flora of Namibia. The genus as a whole is very large though, with about 260 currently recognized species, mostly in Africa but also in Madagascar and a few in Asia. Most of them are small and inconspicuous, with underground tubers from which annual trailing stems emerge, bearing leaves and fruit. The leaves in the other species are smaller, but also succulent. In a few species there is a thick above-ground portion of the tuber, called a caudex, from which the annual trailing stems emerge. There is great variety in the leaves, caudex shapes and growth forms among the different Cyphostemma species, and all of them are worth growing and sought after by succulent and caudiciform (caudex-forming plant) enthusiasts. A number of species are quite rare. This one is fairly rare in nature, but widely grown in and outside of Southern Africa.
As I've said, my first photo shows the reddish leaves emerging in the start of Spring. My second photo shows a group of three in my garden, at the start of December. The leaves are now almost full-sized, and you can also see the flower stems emerging amidst them. The small grey-green plants in the foreground are Kleinias; there are a couple of aloes amidst them and to the left are some carrion flowers, Orbea melanantha. In the backround are a few Quiver Trees, Aloe dichotoma, about which I'll also be writing soon.
