| Stars and Blobs - Part 4
Though sometimes keeping company with other stapeliads, several genera of highly specialized, often bizarre succulent milkweeds have also mastered the secrets of survival in some of the harshest, most arid parts of southern and eastern Africa .
Quaqua consists of about twenty most west South African species formerly listed as carallumas. Most quaquas produce clusters of good-sized upright stems generally covered with prominent tubercles. In species such as Q. mammillaris and Q. armata the tubercles terminate in stout looking (though not very sharp) spine-like points. Quaquas bloom from the upper portions of their stems, and may bear numerous, oddly colored but not very large flowers. In Q. ramosa (from parts of the Little and Great Karoo , farther east than the other species) the tubercles are less spiky and the flowers so deep purple that they look black. Extremely striking looking plants, quaquas unfortunately rot quite easily in cultivation. Keeping them dry in summer and in as bright a situation as possible in winter will help, but they're not easy plants to grow and maintain in good condition.
Both species of Tavaresia, though from summer rainfall areas well to the north of Quaqua territory, share that genus' propensity for quick and dramatic departures from cultivation. Tavaresia are compact plants, with short, erect stems arrayed with small tubercles tipped with slender, almost hair-like, upright pointing spines. When grown in good light the stems turn dark brown, almost black, in striking contrast to the white hair-spines. Tavaresiabarklyi, found from southern Angola east across much of northern South Africa as well as parts of Namibia and Zimbabwe, and the very similar T. angolensis, produce proportionately enormous flowers shaped like an old victrola horn, a large, tubular funnel flaring open at the end. The plants grow quickly and flower fairly easily, but they're quite delicate. Their flower buds will generally drop off after the slightest touch, and excess cold, humidity or water will quickly prove fatal to the plants themselves in winter. Because they do grow well under the right conditions they show up in cultivation from time to time, and with their art-deco colors and huge flowers they make attractive additions to a collection, despite often succumbing to adverse conditions after several years.
Even more frustrating are the spectacular, upright, spiky plants of the genus Hoodia (a recent New York Times article, concerned with an appetite suppressing compound contained within hoodias, managed to refer to the plants both as a weed and as a cactus). The dozen or so species of Hoodia can attain considerable size, with stems over three feet tall in H. currori and H. parviflora, growing into clumps at least as wide. Typical Hoodia flowers resemble inside-out umbrellas, either disc or pentagon-shaped and usually pink or reddish in color. The smaller hoodias once thought of as trichocaulons have rather more standard star-shaped blossoms. Hoodia inhabit a wide stretch of territory, from southern Angola , through Namibia and across the South African border into Bushmanland and the Great Karoo, always in extremely arid places out of reach from coastal fog. Mature Hoodia may grow in rocky areas or right out in the open, but the plants often start as seedlings sheltered by nurse plants that they outlive. Many (but not all) species grow in the winter rainfall (or summer drought) area, and many (but again, not all) of these live in places where winter temperatures drop well below freezing. Combine these somewhat contradictory conditions with rainfall totals of about two inches a year and essentially zero humidity and you have an ideal situation for raising the plants. Lacking whatever exactly their idea conditions are, they're notoriously difficult to keep alive, but they're so impressive and their flowers are so distinctive that people keep trying, using techniques such as bottom heat, and perhaps, prayer.
The next genus, difficult even to assign a name to, exemplifies the stapeliad group's taxonomic follies. Once there was a genus called Trichocaulon, very arid growing plants with smallish, star-shaped flowers. Some trichocaulons had elongated, erect-growing stems with spiny tubercles, others had stems that grew in shapes that defied easy description--call them blobs, more-or-less cylindrical, but lumpy and covered with rounded tubercles, looking more like sea-squirts than plants. The spiny ones were transferred into Hoodia, and the problems began.
Two taxonomists gave two separate generic names to the remaining species, both names honoring eminent members of the succulent plant world. So the plants are now either called Lavrania (after John Lavranos), or the decidedly less euphonious Larryleachia (after, obviously, Larry Leach). The final decision isn't in yet--as of a couple of years ago Lavrania was winning, but recently Larryleachia is making a comeback. Possibly because of its name, Larryleachia cactiformis (from the Richtersveld and Bushmanland) is probably the best-known species. Looking more like a tessellated blob than a cactus, if happy it will eventually produce a few branching stems up to six inches tall and perhaps two inches thick. Its flowers (small, as is the case with all "Ls"), little stars on short peduncles and highly variable in color, emerge from the top of the stems. Overlapping L. cactiformis' range, L. perlata extends into Namibia as well. It can reach as much as a foot in height, while L. marlothii, the "L" with the widest distribution, is smaller, about the size of L.cactiformis, but more freely branching and with distinctly different flowers. These plants inhabit some of the bleakest patches of earth and rock imaginable, where they survive on almost no rain at all. I've seen them almost defy gravity, growing straight out of soulless vertical cracks in carbonate rock, or in sandy Namibian soil, completely exposed to sun and regular winter frosts. Though most grow in winter rainfall areas, they absolutely will not tolerate excess humidity, particularly in overcast weather. A better bet is to water them cautiously in summer and then leave them completely dry for the several cold and wet months of the year.
For champion blob plant of the family, however, we have to travel far to the north, to Somalia , where Pseudolithos was discovered in the late 1950s. Plants of Pseudolithos ("false stones") share the rounded tubercles and inflated spongy texture of Lavrania/Larryleachias, but rather than growing into approximate cylinders, they remain blob-shaped, slowly branching by adding smaller, subsidiary blobs. Their small flowers, produced from near the tops of the plants, can be self fertile, but the seedlings damp off at the drop of a hat, and the plants, which never get more than a few inches across, grow quite slowly. They require good heat, maximum light, a fair amount of water when they're growing, and bone-dry conditions during the winter months. Pseudolithos migiurtinus and the aptly named P. cubiformis resemble each other to the same degree that they don't look like anything else, but not long ago another species, from Socotra, originally classified as a Caralluma, was transferred into Pseudolithos, as P. dodsonianus. This plant, with rough-tubercled, thin, cylindrical stems looks nothing like the other species, and although not easy to grow, is nonetheless easier and quicker growing than the others, so it's creeping into the trade while the others remain expensive, difficult rarities.
A last plant, just for fun, as you'll probably never see one, is the extraordinary Whitesloanea crassa, also from Somalia . This stapeliad grows into a fairly large, granite gray, almost perfect cube. When rediscovered, not that long ago, much was made of the grave danger of extinction the plants faced from being eaten by nomadic Somalian tribespeople. A number were collected, sold for extravagant prices, and more-or-less vanished from sight soon after. I know of none that survived in cultivation and hope that some may still be tucked away in some God-forsaken Somalian cliff face, safe from goats, camels and people.
Many of these plants enjoy surprising amounts of water when they're growing, although lavranias and pseudolithos should always receive less than average water. They need a very fast draining soil, and when dormant they all should be left absolutely dry. Despite all this, many come well from seed and Tavaresia, Lavrania/Larryleachia and Pseudolithos all do reasonably well in cultivation if given the right conditions. Since they're slow growing, slow branching plants they can remain for many years in a small container. Quaqua will grow and spread if they're happy, and some will take a slightly richer soil than the other genera (until they rot off, that is...), and Hoodia will look great until they almost inevitably rot and die.
The Garden has a couple of Quaqua left, not much of the others, but specialist growers offer these plants for sale from time to time for those willing to try them. And they are, after all, some of the strangest things on the face of the Earth.
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