Flora of North America species comparison

usually single, occasionally 2–several, 4-angled with wings 0.1–0.5 mm wide, 1.5–5(–7.5) dm, branching all opposite or secondary and/or tertiary occasionally alternate.

single, terete, 1.5–7 dm, branching all or mostly alternate.

basal and cauline or only cauline present at flowering time;

basal blades spatulate-obovate;

cauline blades linear-oblong to ovate-lanceolate, 0.8–2.5(–6) cm × 3–8(–18) mm.

all cauline or basal occasionally persistent at flowering time;

blade linear to oblong-lanceolate, 0.5–3 cm × 1–5(–7) mm.

cymes of compact cymules;

pedicels 1–2(–4) mm.

open cymes or solitary flowers at ends of branches;

pedicels (10–)20–40(–50) mm.

5-merous;

calyx tube widely obconic to campanulate, 1.5–3(–3.5) mm, mid- and commissural veins about equally prominent, low-ridged, lobes linear-subulate or rarely wider, 2–8(–11) mm;

corolla white throughout (sometimes drying yellow or salmon) or occasionally with a yellow eye, projections of eye into corolla lobes, when present, triangular, without a contrasting border, tube 2.5–7 mm, lobes oblanceolate to narrowly spatulate-obovate, 4.5–15 × 1.5–6 mm, apex rounded to obtuse;

anthers coiling circinately.

5-merous;

calyx tube obconic, 1–3 mm, mid- and commissural veins about equally prominent, not or low-ridged, lobes filiform, 3–8 mm;

corolla white, eye greenish yellow, projections of eye into corolla lobes without a contrasting border, tube 1–3 mm, lobes oblanceolate, 6–18 × 2–7 mm, apex obtuse to acute;

anthers coiling circinately.

 = 32, 34.

 = 32.