Flora of North America species comparison

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

upper portion of primary root somewhat thickened and succulent proximally, otherwise fibrous.

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.

flat-topped or spheric to short cylindric, ± flaccid;

tubercles (5–)6–15(–17) mm;

axils appearing naked;

cortex and pith 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.

19–31(–34) per areole, usually white or brown-and-white (rarely bright reddish brown), glabrous (to hoary);

radial spines (13–)15–23(–31) per areole, in 1 series, bristlelike, stiff;

central spines 1–2(–4) per areole, porrect or strongly projecting, all hooked, (7.5–)10–20(–31) × 0.2–0.4 mm;

subcentral spines 0 [several in M. barbata].

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.

(1.5–)2–3.5(–3.9) × (1.2–)1.8–3(–4.2) cm;

outermost tepal margins long fringed, reaching 1 mm;

inner tepals usually white, cream, pale tan, greenish white, or pale rose-pink, sometimes appearing pale orange proximally due to reflection of yellow anthers, usually with ± sharply defined pink midstripes (often suffused with brown, yellow, pink, red, purple, or green, darkest and brightest distally on most plants), (7.5–)12–17(–21) mm;

stigma lobes green or yellow-green.

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.

green or purple, ovoid or obovoid, (6–)10–16(–22) × (4–)6–12(–13) mm, juicy throughout;

floral remnant 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.

chocolate brown with darker reticulation, 1.3 × 0.9 mm, pitted;

testa hard;

anticlinal cell walls straight;

interstices conspicuously narrower than pit diameters;

pits bowl-shaped.

= 22.

= 22.