A plant possessing Biblical links

Press, 24 October 1980, Page 10

A plant possessing Biblical links

GARDENERS DIARY

Derrick Roonev

Euphorbias have links with man going back to Biblical times. 501..2 2000 years ago King Juba II of Mauritania names the first euphorbia, in honour of his court physician, Euphorbus. According to the Roman historian, Pliny the Elder, who told the tale (and many others: he was an imaginative journalist as well as a naturalist, and was killed, notebook in hand, while recording the great eruption of Vesuvius at Pompeii), Euphorbus found the plant growing on Mount Atlas, and used it in some of his potions. Juba, who married Cleopatra Selene, daughter of Antony and Cleopatra, wrote a book, “De Euphorbia Herba,” extolling the virtues of the discovery. The species concerned was probably Euphorbia resinifera, a cactus-like plant and quite a handsome one, with four-angled, blue-green stems that branch freely to make dense clumps. It has white, gummy sap (as do all euphorbias) and was known as “gum euphorbium.”

This passed out of medical use about three centuries ago, but the species is still in cultivation as an ornamental — it is nearly hardy, and withstands several degrees of frost.

I have just potted up a cutting of this plant, which is one of many cactus-like members of this huge polymorphic genus of upwards of 1000 species, distributed throughout the world. Many of the euphorbias are quite conventionallooking, such as the shrubby winter-flowering species E. characias and its subspecies E. wulfenii, from the Mediterranean, two common garden plants. Euphorbia mellifera, from the Canary Islands, looks just like a rhododendron, and some other species are hardy deciduous perennials. The most likely of these to be encountered in gardens is Euphorbia griffithi, in its selected form “Fire Glow,” which has brick-orange “flowers” and is coming into bloom in my garden now. There is even a semi-

shrubby native of New Zealand, a seaside plant, Euphorbia glauca, which occurs at scattered localities throughout the main islands. This is one of the most handsome euphorbias, with its bright red stems and greyish leaves, but it is unaccountably rare in cultivation and is none too hardv. anyway: I lost my plant several winters back.

These herbaceous or shrubby euphorbias are so different from the succulent ones that it is difficult for many people to accept that they are members of the same genus, but of course the relationship is not determined by the superficial appearance of the whole plant but by the structure of the sexual organs — flowers and fruit.

Nearly all the succulent euphorbias come from the African continent, often from high altitudes. Many are densely spiny, resembling cacti (there is a species from South Arabia named Euphorbia cactus, and another names E. pseudocactus from South Africa), and they range

from huge, tree-size can-delabra-shaped plants to tiny, globular ones. Many are poisonous, and my favourite species is one of the most toxic of all E. obesa, from the Cape Province. The bushmen used the sap of this plant to put a deadly coating on their spearheads.

This is not only a deadly plant, but a very beautiful one, and a superb example of adaption to a hostile climate. Its body represents a pinnacle of succulence. It is globular, thus enclosing the maximum volume of plant in the minimum surface area, and completely leafless. The skin is greyish-green, striped with purplish “growth rings,” and there are eight furrowed vertical ribs, with minute brown teeth.

The male and female flowers are on different plants, and both sexes are needed to produce seeds, which are the only means of propagation. I used to have both, and got plenty of seedlings, but the male plant died, and until a day or two ago my small collection of succulents in-

eluded only the widow. At the age of 15 the widow is scarcely 7cm in diameter, so it is hardly in the “fast-growing” league. Her new husband, an eight-year-old plant, is less than half as high, but is flowering.

When the two are flowering together I shall probably have to hand-pol-linate to make sure of seed, and 1 plan also to try crossing obesa with a couple of nameless cylindrical species, also female: some interesting variants may result. These aristocratic succulents may be slow, but they are not hard to grow. They are more likely to die of kindness than of neglect. All they need is a light hand on the water-ing-can and some slight protection from severe frost in winter: my plant has spent the last 12 years in cold frames, with no more protection than an old rug occasionally thrown over the lights on frosty nights. But it must be kept fairly dry in winter, and now that I think about it I recall that my male obesa died because

or raindrops inai n.epi uuiing on its head through a leaky pane. Only one other euphorbia resembles obesa, and that is E. meloformis, also from the Cape Province. The latter is more broad than tall, and sometimes sprouts from the base to form clumps, whereas obesa is always solitary. While the spent flowers of obesa always drop off, those of meloformis persist; the stalks become woody, and after a while turn into spines, which remain for several years. Euphorbia obesa will grow in quite a shallow pot. but E. meloformis needs a deep one, because it has a thick, turnip-like root. The two species will hybridise freely wherever suitable paired plants are grown side by side, and the plant which was grown for many years as E. valida is now believed to be the result of such a cross in the wild — a. rather invalid species These plants have their look-alikes on the American continent among the true cacti in the species of

astrophytum, which . have areoles (little woolly tufts from which the spines emerge) but no spines in the two most cultivated species, Astrophytum myriostigma (the "bishop’s hat" cactus), which is spineless, scaly, and has four or five deeply furrowed ribs, and A. asterias, which looks just like a -little green sea-ur-chin and is just about as difficult to keep alive. Many euphorbias have spines, but these spring directly from the body of the plant, and not from areoles; only cacti have areoles. Whereas the flowers of most of the euphorbias are insignificant, those of the cacti almost invariable are quite showy.