Flora of North America species comparison

terete, tomentulose or glabrescent;

prickles infrastipular, paired, usually recurved, rarely straight.

ribbed, glabrous;

prickles sparse along ribs, recurved.

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.

stipules linear or filiform, 2–3.5 mm, glabrous;

petiole (2–)2.5–3(–4) cm;

primary rachis 2.5–3.5 cm;

pinnae 1–3 pairs;

leaflets 9–14 pairs, blades obliquely linear, 3.5–6 × 0.7–1(–1.4) mm, margins ciliate, 1 eccentric vein evident abaxially, apex acute, mucronulate, 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.

35–40-flowered, axillary, globose capitula, solitary, 10–12 mm diam.;

bracts spatulate, 1/4–1/3 corolla length.

0.7–1.5 cm.

1–5 cm.

0 mm.

0.2 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 and staminate;

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

corolla pink, glabrous, lobes 5, 1/4–1/3 corolla length;

stamens 10, filaments connate at bases, pink;

ovary stipitate, glabrous;

style attenuate at apex;

stigma tubular.

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.

sessile, straight, linear-oblong, tetragonal, (45–)70–90(–100) × 4–4.5(–5) mm, not constricted between seeds, valves entire, 1–2.5 mm wide, margin 2.5–3.5 mm wide, prickly or unarmed, apex rostrate, rostrum 5–10 mm, faces glabrous.

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

(6–)10–16, dark brown, oblong or subrhomboid, 5–6 × 2.5–3 × 1.5 mm, testa porous, fissural line 90%.