h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Yesterday I went with Gideon de Klerk to a farm about 50 km northwest of Pietersburg, for an environmental impact study. We made a survey of the plants on the farm. The owners are intending to turn it into a free range chicken farm, and an environmental impact study has to be done to minimise the impact of this development.

The farm is currently almost totally undeveloped and the land is wild. There does seem to be some impact from humans. A part of the land had been burned recently, and also, many of the trees had been 'harvested', some of the branches cut off for firewood but the tree itself left alive to regrow new branches.

The habitat is dry, open savannah. The dominant tree species is the Marula, Sclerocarya birrea, which produces delicious fruits. They will leave these for sure, since the chickens can feed on the fallen marulas.

Other prominent tree species include sickle bush, Dichrostachys cinerea, Slender Thorn, acacia permixta, and several species of Commiphora.

The trees aren't a problem. The problem is the smaller plants. There are several extremely interesting small species growing amidst the dry grass or in open patches. They include species sought after by growers of succulents or caudiciforms.

Caudiciforms are plants that have very large and thick basal trunks or storage organs. Such a thick trunk base is called a caudex. Typically, smaller (usually annual) stems or branches arise from the caudex. Caudiciform growers often raise the specimens up to show these off.

Caudiciform species we found on the farm, include the following:

1. Jatropha lagarinthiodes, small member of the Euphorbia family, with small, lobed, hairy leaves, and small yellow flowers. Its tuber is typically underground.

2. Jatropha zeyheri, a relative of the above, but slightly larger.

Only recently had I become more interested in Jatropha species, having seen - while jogging through the neighbourhood, some very nice Jatropha podagrica plants in someone's garden. Our local species are a bit more modest, but if growers start working on them, we might have something quite interesting! In other words, they have horticultural potential.

3. Raphionacme, Khadi-root. I'm not sure of the exact species, but it's another one with a very big round underground bulb. Sometimes, the bulb can protrube a bit above soil level. Again, caudiciform growers lift the bulb. Raphionacme species are popular with growers, but I haven't seen photos of this particular species online yet. It has small but pretty light purplish-pink flowers.

4. Pterodiscus speciosus and ...

5. Pterodiscus ngamicus. Both have bulbous basal trunks, in the case of P. speciosus usually buried in the soil. They are members of the Sesame family, with pretty tubular flowers, varicoloured in S. ngamicus, and bright magenta in S. speciosus. Both sought after by succulent and caudiciform collectors, with great horticultural potential.

5. Adenia digitata. Adenias also make thick basal stems or caudices, in some species they can be gigantic. This one can make a round caudex up to 30 cm thick, in nature usually buried but sometimes exposed. From this thick caudex, thin annual climbing stems arise. It has pretty, lobed, dark green leaves, and make attractive orange-red fruits as well - but warn children against eating them, they are poisosnous! But Adenias are very popular with succulent- and caudiciform growers.

6. Ipomoea albivenia, called Wild Cotton. In the same family and genus as the sweet potato, Ipomoea batatas. I. albivenia grows quite a gigantic caudex, I've seen wild plants that looked like, if fully dug up, the tuber would be more than a metre thick! In this species, the caudex is usually flush with the ground, but sometimes partly exposed. In cultivation, the caudex can be raised, without at all discomfiting the plants. I have several growing at home.

Ipomoea albivenia produces vigorous annual climbing stems from the thick caudex. These bear large, attractive flowers that only open in the afternoon, and then stay open during the night. The seed are contained in balls of fibrous fluff, similar to cotton heads.

7. Talinum sp. These plants are in the Purslane family. They are actually super-abundant in Southern Africa, I've seen farms with concentrations of what must be *thousands* of them. Nevertheless these are poorly known and horticulturally-underexploited plants. They are very inconspicuous in nature. Above-ground parts are tiny - just a small stem with a few succulent leaves, rarely over 2"/5 cm tall. The flowers are pretty but rarely seen, carried only a bit higher than the stems. They are bright yellow.

This plant also forms a carrot like, thick, subterranean stem. When the plant is raised so that a bit of this protrudes, you have a very nice little caudiciform, excellent for a small pot. Can be kept in sun or light shade. Winter dormant - the annual stem dies but the caudex hibernates, to sprout out again next spring. In cultivation plants can become much larger than they usually are in nature.

8. Eupborbia trichadenia. People familiar with our huge tree euphorbias/Euphorbia ingens, will have difficulty believing this species belongs to the same genus. Once again, its above-ground parts are tiny - just a wee thin little stem with a few narrow leaves. It can be identified as an Euphorbia only by its flower-heads or cyathia, and its typical three-lobed fruit capsule.

Once again this species has a thick subterranean tuber, which can be raised to expose it, for a thick-trunk caudiciform effect. The flowerheads are pretty and interesting, and in cultivation the stems and leaves grow much bigger than in natural plants as well - 6"-8"/15-20 cm being possible. A necessary specimen plant for euphorbia collectors, showing the extreme form diversity of the genus when compared to other species.

9. Elephantorrhiza sp. Sumach-bean. A species of the pea family with a huge, woody, subterranean trunk, only sending up to the surface small thin stems with feathery leaves. Flowers and the subsequent pods are carried at ground level.

I don't know if this species has *ever* been tried with a raised caudex, or how it would grow in cultivation.

I do know that in related species, an extract from the bark is used for tanning leather.

Caudiciforms seem to be abundant on this farm. This can be due to:

- The soil being deep and rather sandy. This makes it possible for plants to produce large subterranean bulbs, tubers or submerged trunks.

- The climate being one of extreme, prolonged winter drought. Bulbs, tubers, or below-ground trunks, store up water in summer, and then survive under the shelter of the soil during the winter. From these they can then send up the annual stems carrying leaves and flowers. Many times they are very conservative, not taking chances - sending up only small stems, in case it's a hard year; when abundant rain falls, they might send up a few more, or let the stems grow a bit longer and carry a bit more, and bigger leaves. Some caudiciforms are very responsive like Ipomoea albivenia - the stems of which can be abundant, rapid-growing and carry many, large leaves, during seasons with ample rain.

- Bush fires occurring fairly regularly. Subterranean caudices can survive fires that burn off the above-ground parts. When the caudex becomes very big and a part of it is exposed above ground, it often has thick corky bark to protect it against fire.

None of the above species is threatened with extinction ... but nevertheless, they are not super-abundant and widespread. Like I said, they have great potential with succulent or caudiciform plant collectors and growers. I would feel sad if those plants are destroyed during the development of the land into a chicken farm.

We did find one plant species that is protected by law in South Africa - a carrion flower, Stapelia getliffei. These plants attract flies to pollinate them, by having hairy, smelly flowers mimicking animal carcasses!

In the environmental impact report we will report on these plants and hope that with development, harm to ecologically or biodiversitically (I wonder if that's a real word?!)-important species will be minimised.

Here are pictures of some of the plants we found, and the environment, giving you an idea what the place is like:

http://outdoors.webshots.com/album/575292925utRMkF

Garggh, those wretched pop up ads make my head hurt!

Managed to finally see the terrain; hmm; how big a free range area is the farmer considering? All in all, i'm in favour of free range creatures, but also of free range plants, as you saay, it needs balancing out.

On the smallish farm we have here, we do try very hard to do this, biodiversity takes prime place, the animals are rotated from field to field each week, nothing gets overgrazed & we are 'officially' a Wildlife Corridor due to biodiversity; but we aren't farming commercially; others who are doing it for money may feel differently.

We are lucky that the place has a larger than usual variety of species of birds, plants, in fact most flora & fauna found in this region of Ireland, probably because most of the land has been left wild.

However, when P decided to plant fruit trees & also have free range chickens, he fenced in a section large enough to do this, in a part of the land which was basically composed of very common plants. (It's now pretty much overgrown, the chickens aren't here now, so it's mainly grasses & docks; the chicken poo seems have been a bit too effective!)

in helping find the right balance!

zdt

Hi Terri! Nice to hear from you again.

The farm is six hectares in size ... hope you know what a hectare is? You should, since you've been in France ... they use the metric system there! I guess they don't in Ireland though ...

Hey you can still send me some more piccies of the farm and yourselves!

I hope I'll have the chance to go to this farm again in the future to see how things go ...

Anyways thanks for your comment!

Willem

Willem, I haven't had a chance to read and look at the photos yet, but rest assured I will. In the meantime thanks for writing this, a quick glance through suggests it is very interesting.

Take care, hope Mom and Dad are doing fine.

Websailor