Astrophytum coahuilense f. nudum
Astrophytum coahuilense f. nudum is a flecking-free form of Astrophytum coahuilense, distinguished by a smooth, deep-green body free of the dense white woolly flecking that normally coats the parent species. In this form the plant shows off its clean five-ribbed geometry and rich green skin, giving it a very different look from typical A. coahuilense plants.
Care follows the parent species, Astrophytum coahuilense — see that article for full cultivation detail.
Description
Like the parent, the nudum form is a solitary, globular to slightly columnar cactus that is essentially spineless, with a small number of prominent ribs — typically five, giving the young plant a neat star-shaped outline when viewed from above. Flowers are yellow, typically with a red throat, opening at the crown in the growing season.
What sets nudum apart is the complete (or near-complete) absence of the white trichome flecking that gives normal Astrophytum coahuilense its frosted, silvery-grey appearance. Instead the epidermis is smooth and a deep green, so the ribs and areoles stand out clearly against the plain body. As with other "nudum" forms across the genus Astrophytum, the degree of flecklessness can vary between individual seedlings, and some plants show a few scattered flecks rather than none at all.
Cultivation
Cultivation is as for the parent species; grow it exactly as you would a standard Astrophytum coahuilense. It wants bright light — ideally the brightest position you can give it short of scorching in intense summer afternoon sun — set in a fast-draining mineral mix (see Soil and potting mix). Water sparingly during active growth, letting the mix dry fully between soakings, and keep the plant dry and cool through winter dormancy (see Watering). Keep it above freezing.
One practical note for green-bodied forms: because the flecking that normally reflects light is missing, the bare green epidermis can be a little more prone to sun-stress and marking if a plant is moved abruptly from shade into full sun. Acclimatise gradually in spring, as you would any smooth-skinned cactus.
Propagation
Propagation is by seed, as with the parent species. Because nudum is a body-colour form rather than a stable named cultivar, seedlings from nudum parents will vary — some come true and grow up smooth and green, while others revert toward the flecked wild type; selecting the cleanest, greenest seedlings for further sowing gradually strengthens the trait. As with slow Astrophytum seedlings generally, Grafting can be used to speed early growth, though it is not required.
See also
- Astrophytum coahuilense — the parent species
- Astrophytum — the genus overview
- Propagation — seed · Grafting · Soil and potting mix · Watering