| Stars, No Blobs: Other Asclepiads
- Part 5
After finishing this survey of stapeliads and their relatives, some interesting, quite different succulent members of the family still remain. Before getting into them, though, I'll update you on a few things from last month's column. Larryleachia now seems the dominant name for that group of very strange plants, while the relatively normal appearing members of Pseudolithos are now back in the resurrected genus Anomalluma. Keeping the species count of Pseudolithos the same, a couple of new species (one described just last month) have officially entered world of taxonomic reality. Now on to other things.
Along with the many succulents in the stapelia tribe, and those vining genera such as Ceropegia and Hoya, several other types of succulent milkweeds have attracted the attention of collectors over the years. One of the earliest in cultivation, and possibly the most interesting of these is the south and east African genus Fockea. The relatively few species of Fockea display a considerable diversity of form. They all bear non-succulent, typically ovate and often wavy-edged leaves, along with insignificant dioecious flowers, with small, slightly spiraling petals, but their stems and tuberous roots can develop in different ways. The most commonly encountered species in cultivation have large, tuberous roots and stem bases that may form an above-ground somewhat hemispherical caudex. The most interesting of these is the Great Karoo species Fockea crispa (named for its particularly wavy--crisped--leaf margins). It develops a large, slightly silvery caudex that spirals upward from its tuberous roots, and even as a fairly small plant is partly above ground. Ornamented with projections and tubercles, the caudex merges in the steadily enlarging root tubers, so the plants should be raised higher in their containers as they are repotted. The permanent stems that grow from the apex of the caudex also thicken to a degree and develop bumps as they grow A specimen of this species has been proclaimed the oldest container plant in Europe , having arrived in Vienna in 1796.
Fockea edulis resembles a plainer, less baroque F. crispa. Its leaves are less crisped, its caudex less strangely shaped and decorated, and it also grows quite a bit faster than F. crispa. Its name refers to its occasional use as a wild food plant by indigenous people in its South African home. Fockea angustifolia is a somewhat different looking species, with narrow, dark leaves. It lives in the west of South Africa , and its caudex typically.remains completely underground, the only evidence of the plant being a small tangle of thin leaved stems emerging from a single point on the soil surface. Several other fockeas have a totally different appearance, growing into thick stemmed, clambering shrubs, with branches that twine through the surrounding growth. Some of these plants can become quite large, almost tree-sized, and they include species such as F. multiflora and F. schinzii, from Namibia and southern Angola .
A few other genera of asclepiads have adopted the habit of long stemmed clambering plants. Among these are the Madagascan genera Folotsia and Pentopetia. Folotsias look somewhat like larger, thickened Sarcostemma; it might be more helpful to say that they resemble a tangle of gray skinned garden hoses tossed up into bushes and trees. Their flowers tend to be pretty insignificant, and they more-or-less fall into that group of succulents known as "dead stick plants." They're understandably rare in cultivation, as is Pentopetia, a more interesting looking plant, with shorter stems and large, green non-succulent leaves.
A third growth habit is displayed by the two genera Raphionacme and Brachystelma. These plants consist of a large, somewhat disc-shaped caudex and annually produced thin, leafy stems. In the wild the plants look like small, leafy, non-succulent shrubs, as their caudexes remain completely underground. Raphionacme hirsuta, from the eastern part of South Africa , sends out several stems with ovate, slightly fuzzy leaves and clusters of small, greenish-purple flowers. Planted naturally, it would attract very little interest, but for even a chance of survival, the caudex must be raised above ground. The same holds true with Brachystelma, a fairly large genus of plants with species ranging from South Africa (where most of them live) northeastward and even as far as India in a few cases. Brachystelma are valued for their interesting, almost donut-shaped caudexes and their large, sometimes terrible-smelling flowers, which occur either singly or in umbels, and which come in a wide variety of stapelia colors: from white to almost black, spotted or covered with vibrating hairs. These plants are a challenge to even the best growers, as they require a reasonably rich but rapidly draining soil, a good deal of water when they are in growth (some mountain-growing Brachystelma receive close to a hundred inches of mist and rain a year), and absolute and instant dryness once they go dormant. If kept wet at all during their rest period they will rot with remarkable speed, and even a foot wide caudex can turn into a mass of unpleasant jelly in a day or two. Brachystelma barberae, with a spherically arrayed umbel of Ceropegia-like flowers (with open petals that then close at their tips like little birdcages), probably is the most common in cultivation, while Brachystelma foetidum, with more typical Stapelia-like blooms, has perhaps the vilest smelling flowers.
A final genus of succulent milkweed brings us back to the New World , to east -central Mexico in fact. Often called Gonolobus, Matalea cyclophylla, in spite of its taxonomic confusion, is one of the most desirable New World caudiciforms. The plant consists of a caudex that a first resembles a pointed dome, but which soon turns into a less regular mass of furrows and ridges, topped with a well-behave vining stem that bears deciduous leaves. At first glance Matalea cyclophylla resembles one of the many, almost anonymous caudiciform cucurbits, but its dark purple, star-shaped flowers prove it to be an asclepiad. The flowers, looking quite similar to the blossoms of a Huernia or Stapelia, seem quite out of place on the plants, which haven't been in the trade for too long and which are still quite rare. Nonetheless they have become popular with collectors, both for their novelty value and because of their surprisingly quickly achieved look of great, weathered age.
Matalea and Fockea both respond well to an average, quick draining succulent soil mix. Since they grow under other bushes, they don't require as much light as many succulents. During the warmer months they should receive normal (once a week) water, and while resting they still should be watered perhaps every three or four weeks. Folotsia and their other Madagascan cousins require similar general treatment, with care taken that they don't get too cold. Raphionacme and Brachystelma are a different matter. They need somewhat more light, and when growing should never dry out, but any water during their dormant period will probably prove fatal. They are not easy plants to grow.
The Garden has a number of these unusual asclepiads, including several species of Fockea (some of them big, old specimens) and a number of the Madagascan plants as well. Raphionacme and Brachystelma come and go, but we still have a few--if you're interested you should see them while you can. We've occasionally have had small Fockea to sell, and may have more from time to time.
The Arid House collection includes 67.0434 Fockea crispa, 73.0054 F. cylindrica, 67.0421 F. edulis, 88.0510 F. multiflora; 71.0249 Folotsia grandiflora; 63.0426 Pentopetia cotoneaster; and 68.0179 & 85.1666 Raphionacme hirsuta. 95.1042 Brachystelma barberiae will be temporarily placed in the Arid House for the month of June. |
