Flora of North America species comparison

diffuse or short taproots.

pale gray-green (desert populations) to grass green (eastern populations), above-ground portion flat-topped, hemispheric in old age but usually deep-seated, flush with soil surface, 10–30 × 10–30 cm;

ribs 13–27, very prominent, straight, vertical, or sinuous on desiccated plants, crests ± sharp, without depressions between areoles but sometimes areoles recessed part way into rib.

unsegmented, gray-blue, gray-green, yellow-green, or grass green, flat-topped spheric to short cylindric, 4–40(–45)[–250] × 8–30[–80] cm, apical region appearing copiously woolly (shortly velvety in E. texensis) [glabrous];

ribs (7–)8–27[–60+], very prominent, straight (or only slightly undulate), sometimes helically curving around stems, broadly rounded to nearly keeled, rib crests uninterrupted or ± constricted between areoles;

areoles widely spaced or confluent with age, nearly circular to oblong, with fertile portion as short, broad adaxial prolongation confluent with spine cluster;

areolar glands absent;

cortex and pith hard, not mucilaginous.

(6–)7–8 per areole, mostly decurved or 1 porrect and straight, pale tan, pink, reddish to gray, terete to flattened, annulate, not hiding stem surfaces, minutely canescent with laterally compressed unicellular trichomes;

radial spines (5–)6–7 per areole;

central spine 1 per areole, porrect or descending, straight or distally decurved, (20–)40–60(–80) × 1.5–4(–8) mm.

(5–)7–19 per areole, straw colored, pink, red, gray, tan, or brown, conspicuously annulate-ridged, rigid, stiff;

radial spines 5–14 per areole, straight to curved, 2–5 cm;

central spines 1–4 per areole, straight to curved, terete, flattened, or abaxially ridged.

5–6 × 5–6 cm;

inner tepals bright rose-pink to pale silvery-pink, proximally orange to red, (15–)28–32 × (3–)6(–9) mm, margins usually erose;

stigma lobes pink to pinkish white.

diurnal, near stem apex, near adaxial edges of short adaxial extensions of areoles, broadly funnelform to nearly salverform (more narrowly funnelform in E. texensis);

outer tepals margins entire, apically spinose;

inner tepals yellow or pink to magenta, 2.4–3.2 × 0.3–1.5 cm, margins entire, serrate, toothed, or erose;

ovary scaly, spineless, copiously woolly, with white or pale tan hairs from areoles hiding ovary and flower tube at anthesis;

scales 8–60, margins entire or fimbriate, spine-tipped;

stigma lobes 6–14(–17), yellow, pink, or olive, 1–4.5 mm.

indehiscent (rarely rupturing irregularly), scarlet or crimson, spheric to ovoid, 15–50 × 15–40 mm, fleshy, surfaces not hidden by widely spaced hairs in axils of scales;

scales 13–21, distal scales spine-tipped, minutely puberulent.

either indehiscent or rupturing irregularly, or tardily dehiscent through basal abscission pore, whitish tan to pinkish (bright red in E. texensis), spheric to ovoid or ovoid-cylindric, 10–50 × 10–40[–100] mm, usually nearly dry (strongly succulent in E. texensis), many scaled;

axils of scales copiously woolly (wool hiding surface of fruits except in E. texensis), spineless, distal scales spine-tipped;

pulp red;

floral remnant persistent.

black, spheric-reniform or irregularly obovoid, 2.5–3 mm, glossy;

testa cells flat or very slightly convex.

reddish brown to black, spheric, or subreniform to obovoid, 2.4–4.7 mm, shiny or dull;

testa cells convex or flat.

= 11.

= 22.