Portulacaria
Portulacaria is a small genus of woody, water-storing shrubs and small trees from southern Africa, best known for the tough, easy-going elephant bush (Portulacaria afra). Their thick green stems and neat little leaves store water through long dry spells, and they take pruning so gracefully that they have become firm favourites for bonsai, living hedges and beginner succulent collections alike.
Description
Members of Portulacaria are stem-succulent shrubs with smooth, reddish-brown to grey bark and firm, semi-woody branches that hold their shape well. The small, rounded to teardrop-shaped leaves are fleshy and paired along the stems, giving the plants a dense, twiggy look that responds beautifully to clipping. Leaf colour is usually a fresh mid-green, though several forms carry cream or pink variegation, and stressed plants often blush red along the stem tips.
On molecular evidence the former genus Ceraria has been sunk into Portulacaria, so the genus now also takes in a number of shrubby species once placed there. Modern classification puts all of them in the family Didiereaceae alongside the spiny octopus trees of Madagascar — a surprising relationship given how different they look. Flowers, when they appear, are tiny, star-shaped and borne in small clusters, ranging from pale pink to white; many cultivated plants flower only rarely indoors.
Distribution
Portulacaria is native to the drier parts of southern Africa, especially South Africa, Namibia and neighbouring regions. Plants grow on rocky slopes, in thornveld and in semi-arid scrub, where they endure heat, drought and browsing by animals. In parts of the Eastern Cape, Portulacaria afra forms dense thickets known locally as spekboomveld and is valued both as browse for elephants and other game and, more recently, for its role in carbon capture and land restoration.
Notable species
- Portulacaria afra — the elephant bush or spekboom; by far the most widely grown species and the source of most cultivars, including compact, prostrate and variegated forms.
- Portulacaria armiana — a rare Namibian species with much larger, grey-green leaves and a strikingly tall, whip-like flowering stalk, prized by collectors of unusual succulents.
Several species now placed in Portulacaria were formerly treated under Ceraria and are sometimes still met with under those older names in collections; if you encounter an unfamiliar name, check the Didiereaceae family page for current placement.
Cultivation
These are among the most forgiving of all succulents, which is a large part of their popularity. Give them bright light — a sunny windowsill or a spot outdoors in frost-free climates — in a free-draining, mostly mineral mix. Water thoroughly once the soil has dried out, then let it dry again; they tolerate the odd missed watering far better than a soggy pot. Ease off in the cooler, darker months. Variegated forms are a little slower and softer, and appreciate protection from the harshest midday sun to avoid scorching their pale tissue, while still needing good light to keep their colour.
Portulacaria afra is not frost-hardy and should be kept above freezing; a light winter rest in a bright, cool room suits it well. See Watering and Repotting for general technique.
Propagation
Portulacaria is one of the easiest of all succulents to propagate from cuttings. Snip or break off a healthy stem, let the cut surface callus over for a day or two, then set it in a gritty mix; roots follow readily in warm conditions. Even quite large branches can be struck this way, which is one reason the plants are so useful for hedging and topiary. Seed is possible but seldom necessary. See Propagation — cuttings for a full walkthrough.
Hobby and cultivar notes
The genus punches well above its weight in cultivation. Portulacaria afra is a classic beginner's bonsai subject: it back-buds freely, tolerates hard pruning and thickens up quickly, letting growers build a convincing miniature tree in a few seasons. Popular selections include a low, trailing prostrata form ideal for hanging pots and cascades, and the eye-catching variegata, with cream-edged leaves and pink-flushed stems, sometimes sold as 'Rainbow Bush'. In frost-free gardens the plain green form is also planted as a fast, clip-able hedge.
See also
- Portulacaria afra — the elephant bush, the genus's flagship species
- Didiereaceae — the plant family this genus belongs to
- Bonsai · Soil and potting mix · Watering · Propagation — cuttings · Repotting · Pests and diseases