Flora of North America species comparison

usually unbranched, depressed-spheric, or spheric to elongate-cylindric, 3–7(–14) × 4–9(–11) cm;

ribs 13–15, tubercles usually evident on ribs.

densely covering stem;

radial spines (5–)7–12 per areole, white except for abaxial 2 that are usually purplish pink, 0.6–27 mm;

central spines 4(–5) per areole, terete to angled;

abaxial central spine 1 per areole, purplish pink or reddish brown, somewhat angled, hooked, 16–45(–55) × 0.5–1 mm;

lateral central spines 2 per areole, directed toward stem apex, purplish pink to white, 14–45 × 0.5–1 mm;

adaxial central spine white, usually flat, ribbonlike or dagger-shaped, 17–65(–70) × 1.5–2(–3) mm.

funnelform to campanulate, (1.5–)2.2–3.2 × 1.5–3.5 cm;

outer tepals with greenish or reddish midstripes and yellow margins, oblanceolate, to 24 × 5 mm;

inner tepals yellow, oblanceolate, to 30 × 6 mm;

filaments yellow;

anthers yellow;

ovary minutely papillate, appearing smooth.

irregularly dehiscent, green to tan, often reddish at maturity, ovoid, 10–25 × 6–15 mm, dry;

scales few, scarious margined, minutely toothed, membranous-fringed.

black, 2 × 2 mm, shiny;

testa with rounded papillae.