Flora of North America species comparison

usually slightly flexuous, usually glabrous, not glutinous; short shoots present.

not flexuous, glabrous or sparsely pubescent, hairs appressed, not glutinous; short shoots present.

7–65 mm;

stipular spines terete, straight, 2–35(–55) × 0.5–1.4 mm near base;

petiole (3–)6–12(–17) mm, usually sparsely to densely pubescent, hairs erect;

petiolar gland 1, usually medial on petiole, sessile or short-stalked, circular to slightly elongated, 0.2–1 mm, apex depressed;

rachis 10–55 mm;

pinnae 2–6(or 7) pairs, 6–33 mm;

leaflets 8–19 pairs per pinna, blades flat, oblong, 1.6–6.3 × 0.5–1.7 mm, base oblique and obtuse, apex broadly acute to obtuse, surfaces glabrous, glabrate, or pubescent abaxially, glabrous adaxially.

4.8–17.5 mm;

stipular spines terete, slightly recurved, 4–15(–22) × 0.6–0.9 mm near base;

petiole 4–10 mm, sparsely puberulent, hairs appressed;

petiolar gland 1, just below lowermost pinnae, sessile, circular, 0.1–0.4 mm diam., donut-shaped;

rachis 0–8 mm;

pinnae 1(or 2) pairs, 9–25 mm;

leaflets 6–14 pairs per pinna, blades subterete, linear, 2.8–6.1 × 0.3–0.6 mm, base cuneate, apex acute, surfaces glabrous.

globose heads, densely flowered, 6–10 mm diam., solitary or clusters of 2–5 on short shoots;

involucre at base of head (not obvious).

globose heads, densely flowered, 5.5–7.5 mm diam., solitary or clusters of 2–5 on short shoots;

involucre near middle of peduncle.

12–36(–45) mm.

20–28 mm.

bright yellow;

calyx 1.1–1.8 mm, glabrous;

corolla 1.9–2.8 mm, glabrous;

filaments yellow, 3.5–5.5 mm.

pale yellow;

calyx 0.8–1.2 mm, glabrous or sparsely puberulent;

corolla 1.8–2.2 mm, glabrous;

filaments yellow, 3–4 mm.

oblong, nearly terete or elliptic in cross section, 30–170 × 9–18 mm, constricted or not between seeds.

linear, flattened, 40–90 × 5.5–7.8 mm, sometimes constricted between seeds.

biseriate, uniseriate, or irregularly arranged.

uniseriate.