Geraniums? Well, sort of…
Growing up in California I thought pelargoniums (or geraniums as I called them) weren’t much better than weeds, common, almost trashy plants of no real interest. Here at the Garden, though, we have a number of extremely uncommon members of the Geraniaceae, Pelargonium and their relatives the Sarcocaulon. These two genera of plants from South Africa and Namibia are our succulents of the month, winter growers for the oncoming winter season.
Deciding which of the numerous species of Pelargonium is a succulent and which is not requires us to consider the rather arbitrary nature of the term “succulent plant.” As commonly accepted, a succulent plant has certain morphological modifications that enhance the storage of water. The parts modified generally are either leaves (in which case the plant is a “leaf succulent”), stems (thus “stem succulents”), or, less familiarly, the part of the embryonic plant between the incipient stem and incipient roots (technically, the hypocotyl), in which case the plant is a caudiciform. To a greater or lesser degree almost all pelargoniums fit the bill as stem succulents or caudiciforms, yet no succulent collector would consider a typical flowering “geranium” to be a succulent. Those pelargoniums that are considered rare and desirable succulents are those that are stranger and more difficult to cultivate—in other words there are no real objective criteria, just general agreement by the people concerned. You figure it out! At any rate, there nonetheless are a fairly large number of species of generally summer dormant pelargoniums with relatively few, deciduous leaves and with either extremely swollen stems or mostly underground tuberous bases. This succulent subset of the genus contains some very interesting plants valued for their stem shapes, leaves, and small, often intricate or sometimes extremely weird flowers. Among them are Pelargonium crithmifolium, with finely dissected leaves and thick, upright stems, the dwarf P. crassicaule, with sparse leaves densely covered with silver-blue hairs, and extremely thick, more or less horizontally growing stems. In habitat, old plants of P. crassicaule resemble little weather-beaten boulders, no higher than they are wide, with a few sprigs of foliage poking out of their tops. The combination of extreme sun, aridity and blasting wind that characterizes their habitats produces this spectacularly odd form, and in cultivation it’s probably impossible to duplicate this, but it’s a goal to aim for—the more sun and intense dryness you can give these plants, they better they will look. Another inhabitant of the bleak landscapes of the South African Richtersveld, P. sericeum, differs from most of the succulent pelargoniums in its production of masses of good sized, brilliantly colored, cerise and magenta flowers. Unfortunately this, along with many other pretty remarkable pelargoniums species, is a plant that you probably will never see in cultivation. P. echinatum, with bright red flowers and relatively thin, upright stems covered with the spiny remnants of old leaf bases, and the odd P. gibbosum, with even thinner stems that swell disproportionately at each branching node, looking ultimately like a mass of sausages strung out along long, tangled strings, though not the most spectacular species, can at least be grown reasonably naturally and they do show up from time to time in collections. Although all these pelargoniums grow in the winter and should be rested in summer, many of them (such as Pelargonium crithmifolium and other species either from farther south or east—the northwest parts of South Africa are the most arid) are not terribly fussy about receiving a bit of water when dormant. The second group, with largely underground tubers and rosettes of leaves so finely dissected that they resemble the fronds of ferns, tend to be much fussier about summer water. It probably is best to leave these plants completely dry once their leaves begin to die off (perhaps in April or May), until they begin to show new growth in late fall or early winter. These very odd, but very interesting, plants include species such as Pelargonium juttae, P. rapaceum, and P. appendiculatum. As with the first group, they need as much sunlight as possible (often a problem in winter), a very well drained soil mix and regular, but not too frequent watering when in growth (perhaps every ten days to two weeks, or even less if the skies remain overcast). As is usually the case with these kinds of plants, there are exceptions to every rule. Pelargoniumbonkeri, a plant from the Eastern Cape , with an underground tuber and delicate, ferny foliage, looks like it should be one of the very delicate winter-growing group, but its geographic distribution explains its different cultural needs. South African plants from the eastern half of the country generally grow in summer rainfall areas, and as such, P. bonkeri grows in summer and lies pretty much dormant in winter. As a result, it’s quite a bit easier to grow than most of its relatives. The second genus of succulent geraniums is the more exotic sounding Sarcocaulon. Everything about these plants is bizarre except their flowers. When I first read about sarcocaulons, the author described them as often remaining dormant and leafless for several years on end, then suddenly putting forth a blossom that was nothing more than an ordinary geranium. Actually, these shy flowers, with big, papery petals almost like a matilija poppy, actually are quite pretty, if you are lucky enough to see them. Sarcocaulon , too, come in two forms. One type has reduced, simple ovate leaves, stems generally covered with sharp spines, and—in cultivation at least—small, upwards growing branches. These plants include Sarcocaulon burmanni and S. patersonii. Sarcocaulons generally form a stout upright stem that after reaching about an inch in height, produces several absolutely horizontal branches that can become a foot or more long. The plants look like they’re hugging the ground, but actually they’re raised just above it. Many of the species have bright pink flowers, and during a rainy winter in Namaqualand or southern Namibia , colonies of these low growing, zig-zagging spiny little plants, covered with masses of bright flowers, stand out against the generally barren landscape. Several species have yellow flowers, and one of these, Sarcocaulonciliatum, can become a rather good sized shrubs, up to three or four feet tall, growing, as it often does, in somewhat sheltered nooks on tops of the weather granite domes known as koppies, where the plants receive a bit more moisture. A widespread, white-flowered species, S. crassicaule, lives in both winter and summer rainfall areas. As is the case with most of the spiny species, it too can become surprisingly large, with stems two inches thick radiating out in all directions Another generally summer-growing species, probably the easiest to grow, is S. vanderietiae, from the Eastern Cape. It both flowers and grows quite easily, with its usually white, occasionally pink, one-inch flowers indeed making it look like a little geranium with oddly spiny stems The spines of these sarcocaulons develop from the main vein of their leaves, and often plants will produce small leaves from the tips of their mature spines. Consequently, one shouldn’t brush off old dried leave pf the plants, as it will impair spine production. The species in the second group of sarcocaulons don’t really branch at all, but have strange, more or less horizontally growing little stems shaped something like tiny, deep-keeled boats (even mature plants rarely outgrow a three inch pot). Their leaves are finely dissected (the “fern-leaf” look), often covered with fuzz, and even sparser than the fern-leafed pelargoniums. There are fewer species of these plants, and all of them grow in the intensely arid regions of the Richtersveld, and neighboring southern Namibia . In my experience, these plants—including species such as S. inerme, S. peniculinum and S. multifidum—though looking as if they should be nearly impossible to keep alive, aren’t that hard to grow. A little water during their dormant period won’t hurt them, and they may produce their foliage at almost any time of year. The best rule is to water them when they seem to be growing, and leave them quite dry when their foliage drops until it starts up again.. Sarcocaulon have a waxy coating on their stems that enables them (or so the story goes…) to be burned like candles. Personally, though, I wouldn’t recommend experimenting on plants as rare (and expensive!) as these oddities from some of the driest parts of the South African and Namibian deserts. Sarcocaulon generally have a fairly brief growing season in winter and early spring, but seem to be more capable of withstanding water when leafless and dormant than the tuberous rooted Pelargonium. Essentially, the cultural needs of the two genera are similar, and for those capable of providing warm, extremely bright winter situations, any of these plants are worth a try. The thick stemmed Pelargonium can be propagated by cuttings, and with luck the spiny Sarcocaulon might be propagated vegetatively as well. The tuberous Pelargonium and “boat-stemmed” Sarcocaulon only come from seed. All of these plants have traditionally been considered choice and rare, but now some of the better growers carry them fairly regularly. Though not as expensive as they once were, they are never cheap.
The Garden has some nice Sarcocaulon in its collection, as well as a good collection of succulent Pelargonium in the Arid House. Occasionally we have a few for sale, and I would recommend them for adventurous growers with a bit of experience.