Tylecodon

Tylecodon is a genus of small, winter-growing succulent shrubs in the stonecrop family Crassulaceae, found almost entirely in the winter-rainfall regions of South Africa and Namibia. The genus was split off from Cotyledon to hold its deciduous, winter-growing relatives — a kinship neatly recorded in the name itself, which is an anagram of Cotyledon. Most species are caudiciform, building swollen, often peeling stems that carry a flush of leaves through the cool wet months and then stand bare through the summer drought. Several species are notably toxic to livestock and should be handled with respect.

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Description

Tylecodons range from tiny geophytic dwarfs a few centimetres tall to the tree-like Tylecodon paniculatus, which can reach a couple of metres. What unites them is a thickened, water-storing stem or caudex, frequently clothed in papery, flaking bark and studded with the persistent woody bases of old leaf stalks — a distinctive knobbly texture on many species.

The leaves are fleshy and are borne in spiralled tufts at the branch tips. Crucially, and unlike the evergreen Cotyledon, the foliage is deciduous: leaves appear in autumn, carry the plant through the growing season, and are shed as the plant enters summer dormancy. Flowers are tubular and pendulous, held on wiry stalks well above the body, in shades of greenish-yellow, dull red, pink or cream depending on species. The arrangement of the leaves in a spiral (rather than the opposite, decussate pairs of Cotyledon) is one of the botanical features used to separate the two genera.

Distribution

The genus is concentrated in the arid winter-rainfall belt of the western and southern Cape of South Africa, extending north into Namibia, with the greatest diversity in the succulent-rich Karoo and Namaqualand. These are regions of hot, dry summers and cool, damp winters — a climate that directly shapes the plants' reversed, winter-growing rhythm.

Notable species

Tylecodon paniculatus — the botterboom, the largest species, with a stout yellow-green peeling trunk and airy sprays of red-orange flowers.
Tylecodon reticulatus — instantly recognisable for the persistent net of dried flower stalks that remains over the caudex like a protective cage.
Tylecodon wallichii — a knobbly-stemmed species whose old leaf bases form conspicuous tubercles; one of the species implicated in livestock poisoning.
Tylecodon pearsonii — a compact, freely branching shrublet popular with collectors.
Tylecodon schaeferianus — a dwarf, much-branched miniature much sought after for small containers.
Tylecodon ventricosus — a low, densely branched species common in habitat.

Cultivation

The single most important thing to understand about Tylecodon is its reversed growing season. These plants grow in autumn and winter and rest in summer, so watering must follow that rhythm rather than the calendar most other succulents keep. Water when the plant is in leaf and actively growing through the cooler months, allowing the mix to dry between soakings, and keep it dry — or nearly so — once the leaves yellow and drop for the summer rest. Watering a dormant, leafless Tylecodon in the heat of summer is the surest way to rot the caudex.

Grow them in a very gritty, fast-draining, mostly mineral mix in a container that suits the plant's proportions; the swollen stems appreciate a snug pot and excellent drainage. Give bright light to keep growth compact — thin, stretched stems are a sign of too little light. Protect from hard frost; most are best kept above freezing. See Watering and Repotting for general technique, and be patient, as many species are slow.

In cultivation and collections

Tylecodons are prized by caudiciform and "bonsai succulent" enthusiasts for their characterful, gnarled stems and peeling bark, which give even young plants an aged look. The dwarf species such as Tylecodon schaeferianus and Tylecodon reticulatus are especially collectable for shallow display pots. Propagation is usually from seed, though many of the shrubbier species root readily from stem cuttings taken at the start of the growing season; allow cuttings to callus before setting them in a gritty mix.

Toxicity

Several Tylecodon species contain bufadienolides — the same class of compounds responsible for the toxicity of some Cotyledon and Kalanchoe relatives. In South Africa they are among the plants that cause krimpsiekte ("shrinking disease"), a serious and sometimes fatal cumulative poisoning of sheep and goats that graze them, particularly Tylecodon wallichii and Tylecodon ventricosus. Growers should keep these plants out of reach of pets and livestock and wash their hands after handling. This is a horticultural caution only.

References

Horticultural information for growing these plants as ornamentals. Always confirm plant identification and any handling, grafting, or safety advice against authoritative sources before acting.