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 or slightly 4-ridged but not angled or winged, 1.5–5(–6.5) dm, branching opposite or 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.

cauline and often also basal present at flowering time;

basal blades widely oblong-spatulate;

cauline blades abruptly differentiated, linear, 1–10 cm × 1–3 mm.

cymes of compact cymules;

pedicels 1–2(–4) mm.

flowers solitary or in dense, few-flowered clusters, sessile.

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.

7–12-merous;

calyx tube widely campanulate, 3–8 mm, not ridged, lobes setaceous, 3–17 mm;

corolla pink, eye greenish yellow, projections of eye into corolla tube oblong, without a border, tube 6–10 mm, lobes oblanceolate to narrowly spatulate-obovate, 12–30 × 4–11 mm, apex rounded to obtuse;

anthers slightly twisting helically, not coiling circinately.

 = 32, 34.

 = 28.