Flora of North America species comparison

fleshy taproots, to 24 cm, 5–8 cm diam.

obconic taproots;

secondary roots diffuse.

cylindric to ovoid-cylindric, commonly 5–15(–25) × 3.5–7(–10) cm, flaccid;

tubercles 4 mm diam.;

axils short woolly;

cortex and pith mucilaginous;

latex absent.

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.

21–64 per areole, dark or light colored, depending largely on substrate color, glabrous (to hoary);

radial spines 30–46(–60) per areole, white, bristlelike, 6–10 × 0.09–0.15 mm, stiff;

central spines 1–3(–4) per areole, porrect or strongly projecting, usually hooked, (6–)13–18(–25) × (0.2–)0.3(–0.4) mm;

subcentral spines several, often 12+ per areole, radiating in all directions, often resembling supplementary ring of radial spines, barely distinguishable from radial spines, stouter, longer and dark tipped or purplish.

(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.

2.5 × 2.5–3.5 cm;

outermost tepal margins long fringed;

inner tepals pink to rose-purple, margins sometimes paler or white, at least proximally, 24–26 × 4 mm;

stigma lobes yellow-green to green.

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.

bright red, ellipsoid or cylindric to clavate, (8–)15–30 × 5–10 mm, juicy only in fruit walls;

floral remnant quickly deciduous, leaving conspicuous abscission scar.

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

floral remnant weakly persistent.

black, conspicuously strophiolate, 1.4–2.4 × 1.4 mm, pitted and rugose;

testa hard;

anticlinal cell walls straight (not undulate);

interstices narrower than pit diameters;

pits bowl-shaped;

strophiole tan, large, corky.

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.

= 22.

= 22.