Flora of North America species comparison

± succulent in largest, often massive and difficult to excavate.

deep-seated, aerial portion conspicuous, hemispheric to short cylindric, shape sometimes obscured by profusion of immature branches, 5–23 × (1.5–)4–8(–13.5) cm;

tubercles unusually large, conspicuous, (10–)15–38(–45) × 6–15 mm, ± flaccid or flabby;

areolar glands seasonally conspicuous;

areolar grooves short, extending 1/2–3/4 distance from spines toward tubercle axils;

parenchyma mucilaginous;

pith narrow, ca. 1/10 of lesser stem diam.;

medullary vascular system absent.

7–21[–55] per areole;

radial spines (3–)9–15(–18) per areole, white, gray, tan, or brown, (9–)16–25(–50) mm;

subcentral spines 2–3 in adaxial part of areole;

central spines (1–)3–8 per areole, (tan to) pale gray to black, abaxial central spine porrect or descending, others weakly appressed or ± projecting spines, slightly curved, usually angular in cross section (terete), sometimes flat and grooved on 1 side and rounded on the other, often slightly flexible, (15–)25–35(–55) mm, all equal or abaxial spine longest.

apical or nearly so, 30–50(–60) × (30–)40–70 mm;

outer tepals heavily fringed;

inner tepals 20–25 per flower, bright rose-pink or magenta, often with darker midstripes and paler margins, 30–40 × 4.5–6 mm;

outer filaments greenish white throughout or distally purplish pink;

anthers bright yellow;

stigma lobes 6–13, white or pale yellow, 3–6 mm.

dark green, ovoid to obpyriform or ellipsoid, (10–)13–25(–30) × 12–18 mm;

floral remnant strongly persistent.

reddish brown, ± comma-shaped to spheric, 1.2–1.5 mm, finely and weakly raised-reticulate.

= 22.