Flora of North America species comparison

obconic taproots;

secondary roots diffuse.

diffuse;

upper portion not enlarged.

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.

spheric to cylindric, usually (4–)5–16(–30) × (2.3–)3.5–6.8 cm, firm;

tubercles 4.8–12(–15) × 3.5–7 mm;

axils appearing naked;

cortex and pith not mucilaginous;

latex absent.

(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.

(19–)26–33(–38) per areole, glabrous;

radial spines 17–35 per areole whitish or pale tan, bristlelike, 6–12 × 0.1–0.15 mm, stiff;

central spines (2–)3–4 per areole, 1–3(–4) spines at least hooked (uncommonly 0 hooked), reddish to purplish brown to almost black (rarely golden brown), abaxial 1 porrect, others inconspicuous, appressed against radial spines, hookless porrect spines (3–)9.5–25 × 0.1–0.5 mm;

subcentral spines 1–3 per areole, adaxial to central spines, sometimes transitional to central spines, usually straight and barely distinguishable from radial spines.

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.

ca. 2 × 1.8–3.5(–4.5) cm;

outermost tepal margins minutely fringed;

inner tepals bright rose-pink or rose-purple, 10–16 × 4–8 mm;

stigma lobes yellow-green to green, 3–7 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.

green, turning bright red, scarlet, or carmine (rarely yellowish), elongating until clavate after color change to red is complete, 12–29 × 5–8 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.

black, 0.8–1 × 0.7–0.9 mm, pitted;

testa hard, brittle;

anticlinal cell walls straight;

interstices conspicuously wider than pit diameters;

pits bowl-shaped.

= 22.

= 22.