Flora of North America species comparison

diffuse, upper portion not enlarged.

obconic taproots;

secondary roots diffuse.

nearly spheric to more often cylindric or long cylindric, 5–30 × 5–7 cm, firm;

tubercles 5–12 × 3–7 mm;

axils woolly, bearing 4–15 bristles (0 in young growth) as long as tubercles;

cortex and pith not 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.

14–26 per areole, pinkish or reddish brown to black, glabrous;

radial spines 11–22 per areole, usually white, bristlelike, 5–7 mm, stiff;

central spines (1–)3–4 per areole, abaxial 1 porrect, hooked, longer, stouter, adaxial central spines ascending with radial spines;

subcentral spines 0.

(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.

10–22 mm;

outermost tepals entire or short fringed;

inner tepals cream, usually with pinkish or reddish midstripes, longer in bisexual flowers, 5.4 mm diam.;

stigma lobes yellow to greenish yellow or brownish green, 8 mm.

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 scarlet, clavate or ovoid, 10–25(–35) × 10 mm, juicy only in fruit walls;

floral remnant persistent.

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, 0.8 × 0.6 mm, pitted;

testa hard;

anticlinal cell walls straight (not undulate);

interstices conspicuously wider than pit diameters;

pits bowl-shaped.

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.

= 66.

= 22.