Escobaria zilziana
| Light | Bright light; a little shade from the harshest afternoon sun |
|---|---|
| Water | Sparingly; let the soil dry out fully between waterings, and keep dry through winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Best kept dry and cool in winter, when established plants withstand a few degrees of frost (to roughly −12 °C, ≈USDA zone 8); keep frost-free if watered |
| Propagation | Seed (primary); occasional offsets on clustering plants |
| Toxicity | Not known to be toxic to cats or dogs |
Escobaria zilziana is a small, cylindrical cactus from the arid scrublands of northern Mexico, grown mainly by specialist collectors of the genus Escobaria. Its short, columnar body is closely covered with slender, whitish radial spines pressed flat against the stem, sometimes tipped with pink or brown, and it produces pale flowers near the crown, each petal marked with a darker mid-stripe. First described as Coryphantha zilziana, it was transferred to Escobaria by Curt Backeberg, and more recent phylogenetic work places it in Pelecyphora; older labels and catalogues still list it under Coryphantha.
Description
Escobaria zilziana forms a solitary, cylindrical stem, often with a rounded or slightly cone-shaped top, usually a few centimetres wide and taller than it is broad (roughly 6–10 cm high), though it occasionally branches from the base. As in other members of the genus, the stem is built from spirally arranged conical tubercles rather than continuous ribs, each tubercle grooved along its upper face and tipped with a spine-bearing areole.
The spines are among the plant's most distinctive features: roughly 16 to 22 slender radial spines, whitish and straight, lie almost flat against the body, sometimes tipped with pink or brown; central spines are usually absent. Flowers appear near the growing point in the warmer months, opening in pale shades — whitish, pale yellow or olive-green — with each petal carrying a darker pink to brownish mid-stripe. Reddish, club-shaped fruits about 2 cm long follow, holding the seed.
Distribution and habitat
The species is native to northern Mexico — recorded from the states of Coahuila, Durango and Nuevo León — where it grows in dry, rocky xerophilous scrub, generally at around 800–1800 m elevation. Plants root among rock and gravel on exposed slopes and flats, often tucked in the light shade of low shrubs and bunch grasses, and endure a climate of strong sun, sharp drainage and long dry spells broken by seasonal rain.
Like all cacti, the genus is listed under CITES Appendix II, so international trade in wild-collected plants is regulated. Nursery-grown, seed-raised material is the proper source for collectors; wild collecting is discouraged and, in many places, illegal.
Cultivation
Escobaria zilziana is grown much as other small desert cacti are, with an emphasis on drainage and restraint. Pot it in a very free-draining, largely mineral mix with plenty of grit, and give it the brightest position you can, easing off only from the fiercest afternoon glare under glass. Water thoroughly once the soil has dried out completely through the growing season, then withhold water entirely over winter and keep the plant cool and dry — a proper cold, dry rest both hardens the plant and encourages flowering.
Overwatering, a heavy or slow-draining mix, and a stuffy, damp winter are the usual causes of failure. See Watering and Repotting for general technique, and take care in an unheated greenhouse to keep the plant well ventilated.
Propagation
Seed is the main and most reliable method. Sow onto a warm, gritty surface kept humid until germination, then grow the seedlings on slowly and steadily; the species, like most in the genus, is not fast. Plants that cluster can sometimes be increased by removing rooted offsets, though this is less common than raising from seed. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — nearly always from overwatering or a mix that holds moisture; the stem softens and discolours from the base.
- Etiolation — too little light makes the body stretch and pale, spoiling the compact, spiny form.
- Pests — red spider mites (fine webbing and a bronzed, dulled skin) and mealybugs (white fluff lodged among the tubercles and roots) are the usual offenders. See Pests and diseases.
See also
- Escobaria — the genus overview
- Pelecyphora · Coryphantha — genera in which this species has also been placed
- Soil and potting mix · Watering · Repotting · Propagation — seed · Propagation — offsets