Flora of North America species comparison

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

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

usually opposite (distal sometimes alternate);

sessile;

blades ± 3-nerved or pinnately nerved, elliptic to oblanceolate, 30–120 × 10–40 mm (lengths mostly 3–4 times widths), bases narrowly cuneate (sometimes oblique), margins subentire, serrate, or serrulate, apices rounded to acute, faces setulose (denser on midribs and veinlets) to glabrate, usually 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.

(4–)5;

corollas 4–4.5 mm.

5;

corollas 2.5–3 mm.

9–15 in 2–4 series, linear, 1.5–9 × 0.6–1 mm, apices acuminate to attenuate, sometimes mucronate, abaxial faces pubescent throughout, gland-dotted.

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.

2.5–3.5 mm;

pappi of 40–50 bristles 3.5–4.5 mm.

2.5–2.8 mm;

pappi of 30–40 bristles 3.5–4 mm.

= 20.