Flora of North America species comparison

(from short caudices or stout rhizomes) single, sparsely branched distally, pubescent throughout (nodes sometimes with galls).

(from short caudices) single, sparsely branched distally, puberulent throughout.

usually opposite (nodes often appearing leafy, lateral buds producing 2+ pairs of leaves);

sessile or subsessile;

blades strongly 3-nerved from bases, lance-elliptic to oblanceolate, 50–120 × 5–20 mm, bases ± cuneate, margins entire proximally, serrate distally, apices acuminate, faces puberulent or villous, gland-dotted.

usually opposite (sometimes whorled);

sessile;

blades pinnately nerved, oblong (tapering toward apices), 50–150+ × 15–40 mm, bases connate-perfoliate, margins serrate, apices acute, faces pilose, gland-dotted (abaxial), glabrate, not gland-dotted (adaxial).

5;

corollas 3–3.5 mm.

7–11;

corollas 2.5–3 mm.

8–10 in 2–3 series, oblong, 1–4 × 0.5–1.5 mm, (bases tapered) apices rounded to acute (not mucronate), abaxial faces pubescent throughout.

7–10 in 1–2 series, oblong, 2–4.5 × 0.6–1 mm, apices (whitish) acute to acuminate, abaxial faces villous or puberulent, gland-dotted.

in corymbiform arrays.

in corymbiform arrays.

2–3 mm;

pappi of 30–40 bristles 3.5–4 mm.

1.5–2 mm;

pappi of 20–30 bristles 3–3.5 mm.

= 20, 30, 40.

= 20.