Mammillaria gracilis 'Arizona Snowcap'
Mammillaria gracilis' 'Arizona Snowcap is a cultivated selection of Mammillaria gracilis (the thimble cactus), prized for its dense covering of pure-white, closely appressed radial spines that cap each stem like a dusting of snow. Freely clustering into tidy mounds of small cylindrical stems, it is one of the most widely sold beginner mammillarias and a common sight on nursery benches and windowsills alike.
Description
'Arizona Snowcap' forms low, offsetting clumps of short cylindrical stems, each only a few centimetres tall. What sets it apart from the ordinary species is its spination: the radial spines are numerous, chalk-white and pressed tightly against the stem surface, giving each head a smooth, frosted appearance. The bristly central spines typical of many mammillarias are reduced or absent, so the plant lacks the darker, protruding spines of wild M. gracilis.
Like the parent, it can produce small creamy to pale-yellow flowers near the stem tips, though the selection is grown chiefly for its foliage effect rather than its bloom. The many small offsets detach very easily — a natural dispersal habit of the species that also makes propagation almost effortless.
Cultivation
Care follows the parent species, Mammillaria gracilis: grow it in bright light and a fast-draining, mostly mineral mix, watering thoroughly only once the soil has dried out and keeping it dry and cool through winter. It is tolerant and forgiving, which is a large part of its appeal to newer growers.
Two points deserve special attention. First, the dense white spination benefits from strong light: in too little light the new growth etiolates, spacing out and losing the tight, snow-capped look. Second, because the offsets are so loosely attached, handle the plant gently — heads knocked off in passing will simply root where they fall, but a jostled clump sheds pieces readily. See Watering and Repotting for general technique.
Propagation
Propagation could not be simpler. The abundant offsets separate from the parent with the lightest touch; lay a detached head on dry, gritty mix, wait a day or two for the base to callus, and it will usually root within a few weeks. This vegetative route keeps the selection true to type. See Propagation — offsets and Propagation — cuttings for details.
See also
- Mammillaria — the genus overview
- Mammillaria gracilis — the parent species
- Soil and potting mix · Watering · Propagation — offsets · Repotting