Stenocactus phyllacanthus

Stenocactus phyllacanthus is a small cactus in the Cactaceae family. It grows wild only in Mexico, in dry scrub. Its range includes Jalisco, Hidalgo, Guanajuato, and several other states. Plants grow at 5,580–9,190 feet [1,700–2,800 metres] above sea level. Tall grass can hide them in their native sites. Their flat spines look like dry blades of grass. This helps the plants blend into the grass around them.

Most plants form one stem, though some produce a few branches. The stem can be round, flattened, or shaped like a short cylinder. Reported heights range from 0.10–0.49 feet [0.03–0.15 metres]. Stem width ranges from 0.13–0.33 feet [0.04–0.10 metres]. The skin has a dull green or dark blue-green tone. The top is flat or has a slight dip. Older stems may form a corky patch near the base.

Thin, wavy ribs give the stem its deeply folded look. Most stems have 30–35 ribs, with reported counts of 25–60. Each rib bears few areoles, most often just one or two. White wool covers these spine-bearing pads when they are young. Each areole bears one to three central spines. These broad, flat spines have a lance-like shape. They start reddish, then turn brown or grey with age. One or two may stand up or lean over the crown. Two to seven shorter, white radial spines spread around them.

Flowers appear off and on through spring and summer. They open alone or in groups of two or three. Each bloom measures about 0.05–0.07 feet [0.015–0.020 metres] long. Pale yellow-white petals surround a brown-red throat. The flower has a short tube and pointed inner segments. Small green fruits follow the blooms. The pale flowers and sparse radial spines help distinguish this species from similar ribbed cacti.

The limits of this species remain unclear in the supplied account. Plants sold under its name can differ a great deal. Some with pink or violet flower stripes may belong to other species. Older sources also call it Echinofossulocactus phyllacanthus. The species-level evidence gives no firm cultivation or frost guidance. It also provides no basis for claims about food use or toxicity.