Echinocereus poselgeri
| Light | Bright light with some direct sun; the stems colour up and stay firm in strong light |
|---|---|
| Water | Moderate in growth, allowing the mix to dry between waterings; keep dry and cool in winter |
| Soil | Very free-draining mineral mix with room for the tuberous roots |
| Temperature | Keep above freezing; roughly USDA zones 9–11 |
| Propagation | Seed, cuttings of the pencil-thin stems, and division of the tuberous roots |
| Toxicity | Non-toxic to cats and dogs |
Echinocereus poselgeri is a slender, pencil-stemmed hedgehog cactus from northern Mexico and southern Texas that grows from a cluster of fleshy, tuberous roots. Long placed in its own genus as Wilcoxia poselgeri and still widely sold under that name, it is grown for its wiry, dark stems that scramble up through desert shrubs and its cheerful pink-to-magenta flowers. Its willowy habit has earned it the common names dahlia hedgehog and, in Mexico, sacasil.
Description
Echinocereus poselgeri is unusual among the hedgehog cacti for its thin, elongated stems, which are typically only about a centimetre thick but can reach 60 cm or more in length, sometimes over a metre. The stems are dark green to greyish or purplish, ribbed and clothed in short, closely appressed spines that lie almost flat against the surface — a comb-like pattern that gives the plant a soft, pencil-like look and lets it lean and clamber through surrounding vegetation.
Below ground the plant is anchored by swollen, tuberous roots resembling a small cluster of dahlia tubers, from which the common name comes and which store water and energy through drought. In spring the stems produce silky flowers in shades of pink to purplish-magenta, opening in daylight and set off against the dark stems. These are followed by small, spiny fruits.
Distribution and habitat
The species is native to the Chihuahuan and Tamaulipan desert regions of northern Mexico, in states such as Coahuila, Nuevo León, Tamaulipas and San Luis Potosí, and extends across the border into southern Texas. It typically grows among low desert shrubs and grasses, where the thin stems are supported by the surrounding brush and the tuberous roots sit in gritty, fast-draining soils. The nurse shrubs also give young plants light shade and some protection.
Cultivation
Echinocereus poselgeri is a rewarding grower for those who enjoy something a little different from the usual barrel-shaped hedgehogs. Plant it in a deep, very free-draining, mostly mineral mix that gives the tuberous roots room, and choose a pot deep enough to accommodate them. Give it bright light with some direct sun to keep the stems firm and well coloured; in weak light the thin stems tend to grow soft and floppy.
Water moderately through the warm growing season, always letting the mix dry out before watering again, and keep the plant dry and cool over winter to encourage flowering and prevent rot. The tuberous roots are prone to rot if kept wet and cold, so err on the dry side. Because the stems are slender and lax, many growers stake them or let them trail; see Watering and Repotting for general technique.
Propagation
The species can be raised from seed, sown on a warm, gritty surface in the usual way for hedgehog cacti. It also propagates readily from stem cuttings: a length of pencil stem, allowed to callus before being set in a dry, gritty mix, will root and go on to form its own tuberous base. Established plants can sometimes be increased by careful division of the tuberous roots when repotting.
Common problems
- Rot — the tuberous roots are the weak point; cold, wet conditions in winter are the most common cause of loss.
- Etiolation — too little light produces weak, over-long, pale stems that flop rather than stand or scramble.
- Pests — mealybugs (white fluff, especially around the root crown and among the appressed spines) and red spider mites are the usual offenders. See Pests and diseases.
See also
- Echinocereus — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — cuttings · Pests and diseases