Haworthia
Haworthia is a genus of small, rosette-forming succulents in the family Asphodelaceae, native almost entirely to South Africa. Following recent taxonomic revision the genus has been narrowed to the soft-leaved "window" species — plants with plump, fleshy leaves whose translucent tips let light down into the plant — while many former members have been moved to the related genera Haworthiopsis and Tulista. These little window-leaved rosettes are among the most beloved of all collector succulents.
Description
Modern Haworthia are compact rosettes, typically only a few centimetres across, made up of soft, swollen, water-storing leaves arranged in a tight spiral. The defining feature of the genus as now understood is the leaf window (fenestration): the upper surface of each leaf is more or less translucent, often with a network of pale veins or "windows" running through it. In habitat these clear panels sit at soil level and let sunlight filter down into the buried leaf body, an adaptation to growing partly withdrawn into the ground.
Leaf shape ranges from bluntly rounded and gem-like to flatter and more triangular, and the windowed surface may be smooth, softly bristled along the margins, or marked with fine translucent lines. Colours run from fresh green to olive, blue-grey, and reddish or bronze tones when grown in strong light. The flowers are unassuming compared with the foliage: small, white, two-lipped tubular blooms carried on a slender wiry stalk (an inflorescence) held well above the rosette. Most gardeners grow these plants strictly for the leaves.
Distribution and habitat
The genus is centred in the Western and Eastern Cape provinces of South Africa, with the greatest diversity in the winter- and year-round-rainfall regions of the south-western and southern Cape. Plants typically grow tucked among rocks, in the shade of shrubs and grasses, or partly buried in gritty, mineral soils — sheltered spots that protect them from the fiercest sun and reduce water loss. Many species are extremely localised, and wild populations of the most sought-after forms are vulnerable to over-collection, so responsibly nursery-propagated plants are the right choice for the hobby.
Notable species
- Haworthia cooperi — plump clustering rosettes with rounded, glassy windowed leaf tips; one of the most recognisable "window" haworthias.
- Haworthia cymbiformis — the "boat-shaped" haworthia, forming generous clumps of soft, keeled, translucent leaves.
- Haworthia retusa — a classic flat-topped retuse species with broad, back-turned windowed leaf faces.
- Haworthia truncata — the "horse's teeth" haworthia, its leaves cut off abruptly to present flat windowed ends at soil level.
- Haworthia maughanii — closely allied to H. truncata, with leaves arranged in a rough spiral rather than a fan.
- Haworthia emelyae — variable retuse rosettes prized for beautifully patterned leaf windows.
For the firmer, banded, "zebra" and pearl-studded plants once included here, see the related genera Haworthiopsis (e.g. the zebra haworthia) and Tulista.
Cultivation
Haworthia are among the easiest succulents to keep indoors, in large part because they naturally tolerate — and often prefer — less intense light than most cacti. Bright, indirect light or gentle morning sun suits them well; harsh midday sun can scorch the soft windowed leaves or bleach them an unhappy red-brown. A well-lit windowsill is often ideal.
Pot them in a free-draining, mostly mineral mix and water thoroughly once the soil has dried out, easing off in the plant's resting period. Overwatering, especially in a heavy mix or a cold, dark spot, is the usual cause of failure — the roots and base rot and the rosette collapses. These are small, shallow-rooted plants, so a snug pot is fine; see Watering and Repotting for general technique. Keep them frost-free (roughly USDA zones 10–11, or grow indoors) and give them good airflow.
Propagation
Most Haworthia cluster freely, and the simplest method is to separate the offsets (pups) that form around the base of an established plant, letting any wounds dry before potting them up — see Propagation — offsets. Many species can also be grown from leaf cuttings taken cleanly at the base, and choice or non-offsetting forms are sometimes increased this way; see Propagation — cuttings. Seed is used chiefly by specialists and breeders producing new hybrids and selections, as seedlings are slow and variable — see Propagation — seed.
Hobby and cultivar notes
The soft "window" haworthias have an enthusiastic following, particularly among Japanese and Korean growers, who have selected and hybridised them intensively. Prized traits include large, glassy windows, bold vein patterns, dense white flecking, and unusual leaf forms; H. truncata, H. maughanii, H. cooperi and H. retusa are especially popular parents. Variegated forms — with cream, yellow or pink sectors — are highly sought after and command premium prices; because they carry less chlorophyll, variegates generally grow more slowly and appreciate slightly brighter (but still gentle) light. Named clones are kept true by removing offsets rather than by seed, since seedlings do not come true to a special parent.
See also
- Haworthiopsis — the firmer, banded species split off from Haworthia
- Tulista — robust, pearl-studded relatives also formerly included here
- Soil and potting mix · Watering · Repotting · Propagation — offsets · Propagation — cuttings · Pests and diseases