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.

several, clustered, terete, 5–14 dm, branching opposite throughout.

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 at flowering time;

blade lanceolate to ovate-oblong or ovate, 2.5–6(–8.5) cm × 5–30(–45) mm.

cymes of compact cymules;

pedicels 1–2(–4) mm.

corymboid dichasia of compact cymules;

pedicels 1–5 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 campanulate, 1–2 mm, mid- and commissural veins about equally prominent, not ridged or with low, narrow ridges, lobes triangular to linear-subulate, 0.1–3 mm;

corolla white or cream throughout, tube 2–4 mm, lobes oblong-oblanceolate, 4–7(–9) × 2–3(–4) mm, apex rounded to obtuse;

anthers recurving.

 = 32, 34.