Flora of North America species comparison

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

diffuse, upper portion not enlarged.

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.

nearly spheric, 2.5–12 × 3.5–7 cm, firm;

tubercles 9–10.5(–18) × 3–9 mm;

axils appearing naked;

cortex and pith not mucilaginous;

latex absent.

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.

ca. 9–16 per areole, brightly colored than M. grahamii, yellowish, pale pinkish tan, or brown (smaller spines paler), tipped dark chestnut brown to blackish, glabrous, sometimes ± pubescent when young;

radial spines (8–)10–15 per areole, bristlelike, 6–10(–12) × 0.13–0.23 mm, stiff;

central spines 1(–2) per areole, porrect, hooked, 11–20 × 0.2–0.4 mm;

subcentral spines 0(–2) per areole, adaxial to central spines.

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–)2–3 × 1.2–2 cm;

outermost tepal margins densely fringed, fringes 0.4 mm;

inner tepals pinkish white with sharply defined magenta midstripes;

stigma lobes bright red to red-purple, orange, or magenta, (3–)7–9 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.

bright orange-red, spheric to obovoid, 5–7 × 4–4.5 mm, level with or beneath spines, 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.

black, 1–1.2 × 0.8–1 mm, pitted;

testa hard;

anticlinal cell walls straight;

interstices conspicuously wider than pit diameters;

pits bowl-shaped.

= 22.

= 22.