Flora of North America species comparison

(from tuberous rhizomes) multiple, densely branched distally, puberulent throughout.

(from short rhizomes) single, branched distally, densely pilose.

usually opposite (distal sometimes alternate);

sessile or subsessile;

blades 3-nerved distal to bases, oblanceolate, 20–80 × 5–10(–20) mm, bases cuneate, margins serrate proximally, entire distally, apices acute, faces puberulent (abaxial), glabrous or glabrate (adaxial), gland-dotted.

usually opposite (distal sometimes alternate);

sessile;

blades ± 3-nerved or pinnately nerved, ovate, 3–9.8 × 1.6–5.7 cm, bases clasping or narrowly perfoliate, margins serrate, apices acute, faces (rugose) sparsely pilose (adaxial) or densely pilose (abaxial) and densely gland-dotted.

5;

corollas 2–4 mm.

5–8;

corollas 2.5–3 mm.

7–10 in 1–2 series, oblanceolate, 1–3 × 0.2–0.5 mm, apices rounded, abaxial faces puberulent, gland-dotted.

7–10 in 2–3 series, 4–12 × 1–4 mm, apices (usually white) acuminate to acute, abaxial faces pilose, gland-dotted.

in corymbiform arrays.

in corymbiform arrays.

1–2 mm;

pappi of 20–30 bristles 2.5–3 mm.

2–3 mm;

pappi of 30–40 bristles 3.5–4.5 mm.

= 20, 30, 40.

= 30, 40.