Flora of North America species comparison

terete, tomentulose or glabrescent;

prickles infrastipular, paired, usually recurved, rarely straight.

terete, glabrous;

prickles infrastipular or irregular along internodes, straight or recurved;

brachyblasts present.

stipules linear to subulate, 2–4 mm, puberulent;

petiole 0.1–0.7 cm;

primary rachis 0.3–2 cm;

pinnae 2–8 pairs;

leaflets 5–9(–12) pairs, blades obliquely oblong, 2–4 × 0.4–1.3 mm, margins ciliate, reticulate veins slightly visible abaxially, apex acute to obtuse, surfaces puberulent or glabrous abaxially, glabrous adaxially.

some 1-pinnate, with 1 or 2 pairs of leaflets;

stipules subulate, 1–2 mm, glabrous;

petiole 0.2–0.4 cm, flattened, adaxially bisulcate;

primary rachis 0.2–0.4(–0.7) cm;

pinnae 1 or 2 pairs;

leaflets 2 or 3 pairs, blades obliquely oblong to elliptic, 1.5–3.5 × 0.5–1.5 mm, margins eciliate, pinnate veins prominent abaxially, apex obtuse or retuse to acute, surfaces glabrous.

17–40-flowered, axillary, globose capitula, solitary or in fascicles of 2 or 3, 8–12 mm diam.;

bracts spatulate, 1/4–1/2 corolla length.

5–25-flowered, axillary, globose or semiglobose capitula, solitary or fascicles of 2, 9–12 mm diam.;

bracts spatulate, 1/5–1/3 corolla length.

0.7–1.5 cm.

0.5–1.7 cm.

0 mm.

0.5 mm.

bisexual;

calyx campanulate, lobes 5, (1/3–)1/2–3/4 corolla length;

corolla white or purplish pink on lobes, tomentose or tomentulose, lobes 5, 1/4–1/3 corolla length;

stamens 10, filaments distinct to bases, white;

ovary stipitate, glabrous or pubescent;

style attenuate at apex;

stigma poriform.

bisexual;

calyx campanulate, lobes 4 or 5, 1/5–1/3 corolla length;

corolla purplish pink or white, glabrous, lobes 4 or 5, 1/3–1/2 corolla length;

stamens 8 or 10, filaments distinct to bases, lilac-pink;

ovary stipitate, glabrous;

style attenuate at apex;

stigma poriform.

sessile or stipitate, straight or curved, linear, 25–45 × 3–4 mm, constricted between seeds, valves entire, margin prickly or unarmed, apex acute to acuminate, faces glabrous;

stipe 0.5–1.5 mm.

stipitate, curved, linear, 30–60 × 5–7 mm, constricted between seeds, valves with (3 or)4–6(–8) segments, bulliform, margin prickly on 1 suture, apex cuspidate to rostrate, rostrum 3–4 mm, faces glabrous;

stipe 5–7 mm.

3–8, dark brown, oblong, 3.5–6 × 2–2.7 × 1–1.8 mm, testa smooth or porous, fissural line 40–50%.

(3 or)4–6(–8), brown, lenticular, 4–4.5 × 3–3.5 × 2.5–3 mm, testa porous, fissural line 25%.