Flora of North America species comparison

diffuse, upper portion not enlarged.

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

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.

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

tubercles (5–)6–15(–17) mm;

axils appearing naked;

cortex and pith mucilaginous;

latex absent.

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.

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].

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.

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

floral remnant persistent.

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

floral remnant 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.

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.

= 66.

= 22.