Bishop's Hats, Columns of Pearls and Blue Rocks with Teeth
As winter transforms itself into spring, with the warming sun pushing bulbs into blossom and seducing trees into flowering, the completely counter-intuitive succulent plants of the northwest South African and Namibian coastal regions are getting ready to shut themselves down for the year. Of all the strange plants that inhabit these regions— Namaqualand , the Richtersveld, Namaqualand , Bushmanland, some of the various Karoos—the strangest belong to the family Aizoaceae, within its largest subdivision, the Mesembryanthemoideae (also sometimes given a family rank of its own, as Mesembryanthemaceae). Several thousand species make up this family, and the vast majority of them are confined to these specific parts of the world.
The best known miniature mesembs (we call the larger growing forms iceplant and don’t think much about them at all) resemble small stones or little green, blobby grapes, the genera Lithops and Conophytum respectively, but many of the smaller genera have plants as strange or even stranger, and this month I’m going to talk about some of these less commonly seen, winter-growing mesembs, plants that deserve to be better known, if not more frequently cultivated.
Three of the very strangest Mesembryanthemoideae genera, characterized by pairs of radically dimorphic leaves that make up an entire season’s growth include Monilaria, Mitrophyllum and Meyerophytum. Rather than resorting to camouflage like the stone mimicry mesembs, these plants instead have found an entirely different way to adapt to their extraordinarily harsh habitats. During the dry summer season the plants encase themselves with the dried, dead remains of their last winter’s growth, and look like little desiccated plant corpses, thoroughly dead and unappealing to predators. Monilaria lives in the arid quartz fields of northern Namaqualand, in the far northwest of South Africa, while Mitrophyllum and Meyerophytum live in the even bleaker coastal regions of the Richtersveld immediately to the north. Rain, when it falls here at all, is strictly limited to the winter months, and as much moisture comes from the fog that frequently creeps in from the cold ocean waters to the west.
The six species of Monilaria (the name means string of pearls) consist of upright stalks a few inches tall that look like columns of beads, with each stalk surmounted (during the growing season) by two pairs of new leaves. The first set of leaves, completely joined together, forms a kind of hollow collar. The second pair of leaves, fleshy, elongated, upright as a jackrabbit’s ears, and barely joined at the base, grows through the center of the collar. At the first touch of sparse winter rain the collar leaves burst through confining sheaths made of last year’s dried growth, with the second, elongated pair following almost immediately. Within a few months this second leaf pair dries up and the new year’s growth shrivels and turns into a little globe, another bead, dry and dead looking, on top of the column of previous growths. In species such as M. moniliformis and M. pisiformis the tall second pair of leaves glistens with shiny papillae, bumps composed of large water storing cells. In M. chrysoleuca the papillae are so large that the plants resemble velvety green pipe-cleaners.
Monilaria grow in northern Namaqualand , in the surreal quartz fields of the Knersvlakte, an ancient, dry river delta covered with white quartz pebbles. As the touch of spring approaches the plants go dormant, enduring the long hot, dry season until, eight or nine months later, the first light rains and heavy fogs wake them up, and they send new paired leaves through the top of the string of pearls, and begin another cycle. The stalks slowly clump and multiply over the years. To my astonishment, when I first encountered them in their home territory I stumbled upon what might be called forests of Monilaria (if forests can be less than six inches tall), composed of dense stands of these little plants, each as much as a couple of centuries old.
Sharing the three or four month growing season with Monilaria, the five or so different species of Mitrophyllum take the theme of foliar dimorphism even further. Mitrophyllum live just north of the main range of Monilaria, in the stony hills and flats of the Richtersveld. This is an area that receives an average of only two inches of rain a year, with a supplement near the coast of as much again in fog. When dormant, for three fourths of the year, a Mitrophyllum looks even deader than a dormant Monilaria, just a dried up sheath on a dead-looking stalk, shorter or longer depending on species. When the plants wake up, all at once, a pair of soft, fat, united leaves bursts through the sheath, elongates and spreads horizontally apart. After a few days more a second leaf pair emerges, this one permanently conjoined and upright with a little notch on top resembling the bishop’s miter that gives the genus its name. Mitrophyllum all are quite similar, differing primarily in the size of their leaves and the length of the internodes between their annual growths. Species such as M. mitratum and M. grande have very short internodes, and old plants consist of a short dense thatch of past sheathing leaves with the newest pair on top. In these species the very soft, very fleshy leaves can reach the size of a small banana. In contrast, M. clivorum, with smaller individual leaf-pairs and long internodes, develops into clumps of stalked branches, with only the last season’s dried sheaths obviously displayed.
Though Mitrophyllum grow under extremely arid circumstances, in nature they seek out relatively shaded area, such as the walls of canyons (called kloofs), where they receive protection from the sun and channel whatever moisture is available. Even though the plants themselves can become fairly large, typically they grow in cracks in rocks or tiny ledges on cliff faces, in almost no soil at all. When they choose to grow in soil they generally select patches of extremely unpromising barren sandy clay.
The third genus, Meyerophytum, consists of only one species, Meyerophytum meyeri. Meyerophytum’s version of foliar dimorphism produces small sheathing leaves at the border of the previous growth, and a second pair, fused for about a third of their length, then diverging, forming a “Y” shape. I had always thought of Meyerophytum as tiny plants. Miniature Meyerophytum with leaves no more than an inch long (Mitrophyllum grande, for example, can stretch six inches from leaf tip to leaf tip when in full growth). To my surprise, I encountered patches of Meyerophytum over a foot across, consisting of at least a hundred leaf pairs, growing on a hill with three different Meyerophytum species. With bright purple flowers shining in the sun, the Meyerophytum looked like one of dozens of small shrubby mesembs that dotted the landscape until I noticed its branches made of chains of little “Y”s. A variety of the species, holgatense, with slightly larger leaves and flowers with white centers lives on the arid coast, near the regions where diamonds are mined and trespassers are quite unwelcome.
Not surprisingly, these plants have unusual cultural needs. In late fall or early winter their new leaves swell inside the sheaths of the old growths. At this time watering should begin, but even during their growth period they should only be watered perhaps every two weeks. After three or four months, perhaps in late February, the leaves will become rather floppy, signifying the start of dormancy. At this time stop watering, and leave the plants absolutely dry for the next eight or nine months. They may look dead during this time but they’re not; if you do water them, however, they will become quite dead indeed. A fast draining soil mix low in organic matter will suit them, and they should get very bright light, but, since their growth period is accompanied by frequent fog and overcast skies—and Mitrophyllum at any rate usually seek out a somewhat shaded habitat—they don’t need as much light as a Lithops. They might do quite well on a fairly sunny window sill, and they’ll never outgrow a small container.
These three odd genera share their habitat with a vast array of other mesembs, and among these other plants are a few genera with angular, sculptural, often toothy little leaves and a generally bright to sky-blue color. Among these plants are the relatively few species of the genera Juttadinteria, Dracophilus, Nelia and Schwantesia. These plants grow into very small clumps of very thick, succulent leaves, often with a waxy texture and their typically little, quite harmless teeth arrayed in ridges toward the ends of their leaves. Some Schwantesia live in the far east of Bushmanland, where the extremely sparse rain falls in summer (when it falls at all), rather than winter, the others all live closer to the coast, sometimes right at the coast. Selected growing sites may include imperceptible cracks in the side of a boulder, with room for no more soil than you could pinch between your fingers, or fairly high altitude desert flats, with nights well below freezing and atmospheric humidity effectively at zero. Nelia, which look as if they’re carved out of blue soap (pointed out by Steven Hammer, I believe), live near the coast, where it doesn’t freeze. Oddly, for a mesemb, their white flowers open early in the day and remain open for several days and nights. Juttadinteria shares the coastal habitat with Nelia, but over a slightly expanded range, north into Namibia and a bit farther east as well. Some of its species have teeth, some don’t, and some of the toothless species have leaves with a less angular shape as well.
Dracophilus, closely related to Juttadinteria, may be slightly more compact in its growth habit. Its flowers may be pink as well as white, but, as with most of plants that require strong light in winter (with the exception of the rather easily flowered Nelia), it’s not that easy to flower the plants. As with Juttadinteria, a happy Dracophilus resembles a tiny mound of blue, angular, almost crystalline pebbles, but growing in ground or rocks of distinctly different coloration, the plants seem to have chosen a method other than camouflage for survival. Their habitat choice may be their best survival tactic. There are few insects there other than occasional extremely slow-moving, solitary, wingless and insanely well camouflaged grasshoppers, or bizarre, lumbering, black armored crickets. The scarcity of predators may be the secret of the plants’ survival.
Sharing the taste for astonishingly arid habitats, the plants of Schwantesia also resemble small heaps of geometric blue pebbles, with their clusters perhaps even more compact and their individual leaves often a bit broader. Whether east or west of the winter-summer rainfall border, Schwantesia live in places where the yearly rainfall won’t be much more than two inches in a good year, and extended droughts are more the rule than the exception.
All these blue plants differ from Lithops and Conophytum (as well as Mitrophyllum and its relatives) in that their leaf pairs last for many years, and don’t dry into protective sheaths. These plants need maximum sun, a nearly instantly draining soil devoid of organic matter, and fairly infrequent water even when in active growth. Ideally, with bright sun in winter, they could take water about every two weeks, but with low light, they should stay dry until the clouds clear up, regardless of whether that represents a delay of a week or two or even more from their “schedule.” Those Schwantesia that live in summer rainfall regions (some clones of S. herrei, and S. ruedebuschii in particular) could be treated much like a summer-growing Lithops, with water every two weeks or so from late spring through mid-autumn, but again, erring on the side of dryness won’t hurt.
The Garden has some old plants of Mitrophyllum that regularly display their pale yellow flowers. We also have a single, nicely grown Schwantesia, but could use some examples of the other genera to round out the collection. A few specialist succulent growers offer Monilaria and Meyerophytum for sale, Mitrophyllum a little less frequently, and various species of the “blue” plants from time to time as well. For a reasonably advanced grower who wishes to attempt some of the most bizarrely evolved plants in existence, I would suggest giving a few of these a try.
