Flora of North America species comparison

erect (some dwarf alluvial forms may be ascending or almost prostrate), branched in distal 2/3, occasionally almost near base, (5–)15–75(–100) cm.

erect, ascending, or submerged and/or floating (in aquatic forms), usually producing numerous axillary shoots below 1st-order inflorescence or at proximal nodes (especially in aquatic plants), 40–70(–90) cm.

ocrea deciduous to partially persistent at maturity;

blade lanceolate or lanceolate-linear, rarely oblong-lanceolate, usually very gradually narrowed at both ends, (4–)7–25(–40) × (1–)1.5–4(–5) cm, at least 4 times as long as wide, base narrowly cuneate, very rarely broadly cuneate, margins entire, flat or rarely weakly undulate, apex acute, very rarely subobtuse.

blades very variable, in aquatic submerged forms usually ovate-lanceolate to lanceolate, glabrous or nearly so; in terrestrial forms lanceolate, papillose-pubescent abaxially, (2–)3–7 × (0.5–)1–3 cm, usually ca. 3.5–5 times as long as wide, widest near middle, thin or occasionally subcoriaceous in terrestrial plants, base cuneate, margins entire, flat or undulate, apex acute or subobtuse.

terminal, occupying distal 1/2 of stem, occasionally most of stem, golden or greenish yellow, usually rather dense or interrupted in proximal part, broadly paniculate, branches spreading.

terminal and axillary, terminal usually occupying distal 1/5 or less of stem, dense or interrupted in proximal 1/2 usually narrowly paniculate (branches simple and comparatively short).

articulated near base or at least in proximal 1/3, filiform, 3–8 mm, articulation weakly evident.

articulated in proximal 1/2, or almost near middle, filiform (slightly thickened distally), 2.5–4(–6) mm, subequal to inner tepals or at most 2 times longer, articulation indistinctly swollen.

15–30 (occasionally more) in rather dense whorls;

inner tepals narrowly triangular or narrowly rhombic-triangular, 2.5–3(–3.5) × 0.75–1.2(–1.5) mm (excluding teeth), normally ca. 2 times as long as wide, base truncate or broadly cuneate, margins prominently dentate, apex acute, very rarely subacute, straight, teeth 2–3(–4), normally at each side of margins, subulate-filiform, bristlelike, 1–3.5 mm, usually 1.5–2 times as long as width of inner tepals;

tubercles 3, equal or subequal, apex acute or subacute, smooth.

10–20 in whorls;

inner tepals ovate or elliptic, occasionally elliptic-triangular, 2–2.5(–3) × 1–1.5(–2) mm, base truncate or broadly rounded-cuneate, margins entire or very indistinctly erose, apex subacute or obtuse;

tubercles 3, equal or subequal (much narrower than inner tepals), smooth or slightly verrucose.

light brown, small, 0.9–1.75 × 0.6–1 mm.

brown or dark reddish brown, 1.5–2.2 × 0.8–1.2 mm.

= 40.

= 20.