Grooved nipple cactus

Coryphantha sulcata bodies may be either branched or unbranched, and tend to form clumps. Typical of species of the genus Coryphantha, the body surfaces are divided into conical tubercles with rounded tops, looking like closely packed, green chili pepper bottoms. Atop each tubercle arises a cluster of slender, stiff spines, from a spot called the areole. Arising from each areole are 9–18 spines, which are yellowish or pinkish when young, but later turning gray to nearly white with dark reddish brown or black tips. These spines can be of two types: There are 0–4 "central spines" of at which at least one sticks straight up from the areole's surface, while other central spines, if present, are directed more obliquely; then there are 8–15 "radial spines" which are 9–16 mm (0.35–0.63 in) long, stout and radiating outward, keeping close to the cactus body's surface. Flowers are 40 mm–60 mm × 35 mm–55 mm (1.6 in–2.4 in × 1.4 in–2.2 in) in size and arise at the body's apex, or nearly so. The tepals are golden yellow or rarely greenish yellow, and at their bases bright red or rarely brownish red or greenish. Stigmas are 7–10 lobed, and whitish or greenish yellow. Fruits usually start out green but become dull red and broadly egg-shaped.

In Texas Coryphantha sulcata occurs in shrublands and savannas with gravelly, sandy to clayey soils, at elevations of 300–1,100 m (980–3,610 ft).