Flora of North America species comparison

floating or creeping and ascending to erect, terete, 10–100(–300) cm, simple or branched, glabrous or sparsely to densely villous, hairs sometimes viscid on emergent distal stem.

erect or strongly ascending, sharply 4-angled and 4-winged, 30–200 cm, simple to densely branched, glabrous.

stipules broadly ovate-deltate, 0.6–1.6 × 0.4–1 mm, succulent, apex acute or obtuse, gland-tipped, rarely divided into 3 parts;

petiole flattened or narrowly winged, 0.2–6 cm;

blade narrowly oblong or elliptic to ovate, broadly obovate, or orbiculate, (0.4–)1–10 × 0.4–4 cm, base narrowly cuneate or attenuate, margins entire, apex obtuse or rounded to acute, sometimes mucronate or glandular-mucronate, surfaces of floating leaves glabrous, those of emergent leaves glabrous to sparsely or densely strigillose at least adaxially;

bracts scarcely reduced.

stipules deltate, 0.4–0.5 × 0.2 mm;

sessile and continuous with wings on stem;

blade lanceolate or narrowly lanceolate to narrowly ovate or elliptic, 2–20 × 0.2–5 cm, base acute or rounded, margins entire, often minutely scabrid, apex acute or acuminate, membranous, surfaces glabrous or sometimes minutely puberulent on abaxial veins;

bracts linear, mostly reduced.

on emergent stems sometimes in leafy racemes, flowers solitary in leaf axils;

bracteoles (rarely absent), deltate, squamate, 0.5–1 × 0.5–1 mm, apex acute, attached near base or on lower 1/2 of ovary.

open, leafy racemes, flowers solitary in distal axils;

bracteoles deciduous, usually attached near base of ovary, without subtending glands, lanceolate to subovate, 0.5–1 × 0.2–0.5 mm, apex acute.

sepals narrowly deltate or lanceolate, 3–12 × 1.5–4 mm, apex acute or acuminate, surfaces glabrous or sparsely to densely hirtellous;

petals yellow, obpyramidal,7–24 × 4–13 mm, apex mucronate or emarginate, up-curved;

stamens 10(or 12), in 2 unequal series, bright yellow, filaments suberect or reflexed, shorter ones 1.4–4.2 mm, longer ones (1.9–)3.3–6 mm, anthers oblong, 0.5–2.2 mm;

ovary subcylindric or truncate, 6–20 × 1.5–3 mm, apex somewhat broader, glabrous or sparsely to densely hirtellous;

nectary disc slightly raised on ovary apex, 2–2.5 mm diam., lobed, glabrous or fringed with long hairs;

style (1.9–)2.4–7.3 mm, glabrous or sparsely to densely hirtellous on proximal 1/2, stigma flattened-globose, 0.9–1.2 × 1–2.5 mm, sometimes shallowly or deeply 5-lobed, as long as or exserted beyond anthers.

sepals ovate to lanceolate, 7–12 × 1.5–4 mm, apex acute or short acuminate, membranous, margins usually minutely scabrid, surfaces usually glabrous, sometimes puberulent abaxially;

petals orbiculate-obovate, 10–20 × 10–18 mm, short-clawed;

stamens 8 in 2 subequal series, yellow, filaments 1.3–2.5 mm, anthers oblong, 1.3–1.6 × 0.5–0.6 mm;

ovary obconic, sharply 4-angled and 4-winged, 6–10 × 2–4.5 mm, glabrous or minutely puberulent;

nectary disc plane on ovary apex, 3–5 mm diam., 4-lobed, glabrate or ringed with short hairs;

style 2.5–3.2 × 0.5–0.6 mm, stigma globose, 1–2 × 1–2 mm, not exserted beyond anthers and pollen shed directly on it.

cylindric, subterete to obscurely 5-angled, straight or curved, 10–40 × 2–4 mm, with thick woody walls, irregularly and tardily dehiscent, pedicel 7–60(–90) mm.

rarely sharply curved, subclavate to oblong-obovoid or narrowly obpyramidal, sharply 4-angled and 4-winged, 10–25 × 3–5 mm, glabrous, pedicel 2–15 mm.

embedded in elongated piece of endocarp, 1–1.5 × 0.9–1.3 mm.

oblong or subcylindric, 0.5–0.6 × 0.2 mm, striate, raphe very narrow and inconspicuous.

= 16.

= 16.