Argyroderma fissum
| Light | Very bright light; full sun in cultivation for tight, compact growth |
|---|---|
| Water | Winter grower; water autumn to spring, keep dry through summer dormancy |
| Soil | Extremely gritty, mineral mix with sharp drainage |
| Temperature | Frost-free; keep above about 5 °C, USDA zones 9b–11 |
| Propagation | Seed (primary); division of established clumps |
| Toxicity | Non-toxic to cats and dogs |
Argyroderma fissum is a clump-forming dwarf succulent from the winter-rainfall region of South Africa, one of the "living stone" mesembs prized for its pairs of smooth, silvery leaves. Unlike the near-spherical bodies of some of its relatives, A. fissum produces more elongated, finger-like leaves that meet in a deep V-shaped cleft, and it clumps steadily with age into low silvery cushions topped by daisy-like flowers that may be yellow, pink, purple or red. It belongs to the genus Argyroderma, whose name means "silver skin".
Description
Argyroderma fissum grows as a low, branching clump of paired leaves. Each pair is fused at the base and splits into two long, semi-cylindrical to finger-shaped lobes separated by a deep central fissure — the feature that gives the species its name. The leaves are smooth, firm and chalky grey-green to bluish-green, sometimes reddish at the tips, the pale colouring coming from a waxy bloom that helps reflect the fierce sun of its habitat.
New leaf pairs emerge from the fissure of the old ones, and over the years the plant offsets to form a cushion of many heads. Flowers are daisy-like and appear singly from the cleft, variable in colour — yellow, pink, purple or red, usually with a paler centre. As with other mesembs, the flowers are followed by capsules that open when wetted, releasing seed a little at a time.
Distribution and habitat
The species is native to the Knersvlakte and surrounding areas of the northern Western Cape in South Africa, a starkly beautiful region of quartz gravel plains. There it grows in winter-rainfall desert, often nestled among white quartz pebbles that camouflage the silvery leaves and keep their roots cool. Rain falls mainly in the cool months, and the plants endure a long, hot, dry summer by resting.
Understanding this rhythm is the key to growing the plant well: it is a winter grower that is active when most other succulents are dormant, and dormant through the heat of summer.
Cultivation
Argyroderma fissum rewards patience and restraint. Grow it in an extremely free-draining, almost purely mineral mix in a pot deep enough for its root system, and give it the brightest light you can — full sun in most climates keeps the clump compact and well-coloured. In dull light the leaves stretch and the plant loses its tidy, pebble-like form.
The watering calendar matters more than the amount. Water from autumn through spring when the plant is in growth, letting the mix dry between soakings, and keep it almost completely dry through summer while it rests. Overwatering — especially in summer, or while a new leaf pair is forming — is the quickest way to lose the plant to rot or splitting. See Watering and Repotting for general technique.
Propagation
Seed is the main method and the way most plants in cultivation are raised. Sow the fine seed on a gritty, mineral surface in autumn as the growing season begins, keeping it lightly humid until the tiny seedlings establish; they are slow but not difficult. Established clumps can also be divided, lifting the plant and separating rooted heads — best done at the start of the growing season so the divisions can root before dormancy. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — almost always from watering during summer dormancy or from a mix that holds moisture; the leaves go soft, translucent and mushy.
- Splitting and stacking — too much water while the new leaf pair is developing causes the old leaves to burst or the plant to build up multiple leaf pairs at once instead of cleanly replacing them.
- Etiolation — insufficient light makes the leaves elongate and flop, and the silvery colour fades to plain green.
- Pests — mealybugs can hide in the fissure and around the roots; watch for white fluff and check the root ball at repotting time.
See also
- Argyroderma — the genus overview
- Watering · Soil and potting mix · Propagation — seed · Propagation — offsets · Repotting · Pests and diseases