Flora of North America species comparison

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

(from short rhizomes) single, branched distally, usually glabrous or glabrate, sometimes pilose.

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 (distal sometimes alternate);

sessile or subsessile (petioles to 5 mm);

blades 3-nerved from bases, lanceolate to lance-linear, 30–50 × 5–13 mm, bases narrowly cuneate, margins serrate, apices acute, faces glabrous adaxially, sparsely pilose abaxially, densely gland-dotted.

5;

corollas 3–3.5 mm.

5;

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 2–3 series, elliptic, 1–4.5 × 0.2–0.8 mm, apices rounded, abaxial faces pilose, gland-dotted.

in corymbiform arrays.

in corymbiform arrays.

2–3 mm;

pappi of 30–40 bristles 3.5–4 mm.

2.5–2.8 mm;

pappi of 30–40 bristles 3.5–4 mm.

= 20, 30, 40.

= 20.