Flora of North America species comparison

obconic taproots;

secondary roots diffuse.

short, obconic taproots;

secondary roots diffuse.

top-shaped, flat-topped (aerial part sometimes hemispheric in old age or in dense subtropical vegetation), protruding above ground 0–2 × (4–)7.5–15 cm, firm;

tubercles 9–15(–20) × 3–7 mm;

axils with short wool, bristles absent;

cortex and pith not mucilaginous;

latex abundant in healthy tissue throughout cortex of stem, tubercles, and sometimes flower receptacle, sticky, white.

usually flat-topped (in old age or under dense brush hemispheric), 4–20 × 9-25(–30) cm, firm;

tubercles 10–17 × 6–8.5 mm;

axils woolly, wool 5–8 mm, bristles absent;

cortex and pith not mucilaginous;

latex sticky white, abundant in healthy tissue throughout cortex of stem, tubercles, and sometimes flower receptacles.

(8–)10–18(–27) per areole, usually brownish, darker at tip, glabrous;

radial spines (8–)10–22(–26) per areole, white to white-and-brown or brown, needlelike, 6–15(–16) mm, stiff, abaxial spines longest;

central spines (0–)1(–4) per areole, porrect or ascending, not hooked, (0.5–)2–8 × 0.15–0.45 mm;

subcentral spines 0.

11–14(–16) per areole, white to straw yellow, glabrous;

radial spines 10–12 per areole, whitish to pale yellowish tan, needlelike, 20 mm, stiff;

central spines 1–2(–4) per areole, ± porrect or 1 ascending and 1 descending, straight or slightly curved, 10 mm;

subcentral spines 0.

1.9–3.8 × 1.5–3 cm;

outermost tepal margins entire;

inner tepals white, greenish or cream to pale pink, with tan, pink, greenish, or brownish midstripes, 11–19 × 2–2.5 mm;

stigma lobes externally green, internally green or red (or pink), 2.5–3 mm.

3–4 × 2.5–3.5 cm;

outermost tepal margins densely minutely fimbriate (at 10x);

inner tepals greenish white to greenish yellow, 14–17(–25) × 2–3 mm;

stigma lobes yellow-green to pale green, 2–3 mm.

brilliant red: scarlet, carmine, or crimson, obovoid to clavate, 10–35(–40) × 5–8 mm, juicy only in fruit walls;

floral remnant weakly persistent.

whitish green proximally, pale green distally with pale rose-purple on sunlit portions, obovoid to clavate, 15–26 × 7.5–15 mm, juicy only in fruit walls;

floral remnant persistent.

reddish brown, sometimes yellowish when fresh, 1–1.2 mm, deeply pitted;

testa thin, relatively flexible;

anticlinal cell walls sinuate, interstices narrower than pit diameters;

pits cavernous or deeply concave.

reddish brown or orange, 1.1–1.3 × 0.9 × 0.8 mm, pitted;

testa intermediate, anticlinal cell walls undulate, interstices much narrower than pit diam., pits deeply concave, elongate.

= 22.

= 22.