Lithops olivacea
| Light | Very bright light, including some direct sun; a sunny windowsill or bright greenhouse |
|---|---|
| Water | Very sparingly; keep dry during summer dormancy and after flowering, no water in mid-winter |
| Soil | Extremely gritty, mostly mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; USDA zones 9b–11 |
| Propagation | Seed (primary) |
| Toxicity | Non-toxic to cats and dogs |
Lithops olivacea is a small, clump-forming "living stone" from South Africa, prized by collectors for its smooth, olive-green translucent windows that give the plant a jewel-like, glassy face. Like all Lithops, each plant consists of a pair of fused, pebble-shaped leaves buried almost to the rim in the soil, camouflaging it among the surrounding stones until its bright yellow flowers appear in autumn.
Description
Lithops olivacea forms a body of two thick, fused leaves shaped like a truncated cone, usually 1.5–3 cm across at the flattened top. The upper face is dominated by a large, smooth, translucent window in shades of olive to greyish green, often with a slightly darker or bluish cast; through this window light passes down to photosynthetic tissue inside the leaf, an adaptation that lets the plant sit low in bright, exposed habitat. A narrow fissure runs across the top, and it is from this slit that both new leaves and flowers emerge.
With age the plant slowly divides to form small clumps of a few to several heads. Yellow daisy-like flowers open in autumn, usually in the afternoon, and are large enough to nearly hide the body when fully expanded. A well-known variety, L. olivacea var. nebrownii, has a reddish or brownish window colour rather than the typical green.
Distribution and habitat
The species is native to arid, rocky country in the Northern Cape of South Africa, where it grows wedged among quartz and other pale stones in open, sun-baked terrain. Rainfall is low and highly seasonal, and the plants survive long dry periods by drawing on the water stored in their swollen leaf pair. Their stony colouration is true camouflage, helping them escape grazing animals in a landscape with little other cover.
Cultivation
Lithops olivacea is grown much like other Lithops and rewards patience over fuss. The single most important thing is a very free-draining, mostly mineral mix and a strict respect for the plant's growth cycle. Give it as much light as you can — a bright, sunny windowsill or an airy greenhouse — as too little light causes the body to stretch and lose its compact, stone-like form.
Watering must follow the seasons rather than the calendar alone. Water in autumn (around flowering) and again in spring, always letting the mix dry out completely between drinks. Through the heat of summer and the cold of mid-winter the plant is dormant and should be kept dry. In late winter to spring a new leaf pair grows inside the old one and draws on it for moisture; do not water while the old leaves are shrivelling away, or the plant may take up too much and split or rot. See Watering and Repotting for general technique.
Propagation
Seed is the usual and most reliable method. Sow the fine seed on the surface of a gritty, mineral mix, keep it lightly humid and warm, and be prepared to grow the seedlings on slowly over several years. Established clumps can sometimes be divided when repotting, separating rooted heads, but this is done less often than raising plants from seed. See Propagation — seed for a full walkthrough.
Common problems
- Rot — by far the most common cause of loss, almost always from watering during dormancy or using a mix that holds too much moisture; the body goes soft and translucent-mushy.
- Etiolation — too little light makes the body elongate upward and pale, losing the flat, stone-like top.
- Failure to shed old leaves — watering too early in spring can trap the plant in a swollen double body; withhold water and let the old pair dry down completely.
- Pests — mealybugs (white fluff in the fissure and around the roots) and, less often, spider mites are the usual culprits. See Pests and diseases.
See also
- Lithops — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed