Flora of North America species comparison

erect or ascending to creeping or floating, terete or sometimes angled distally, 20–300(–450) cm, usually densely branched, sometimes simple, glabrous if floating, or densely villous and viscid throughout, or rarely just on inflorescence.

prostrate or decumbent and ascending at tips, slightly ridged, often well branched, 5–70 cm, glabrate to sparsely strigillose, denser on distal parts.

stipules (rarely in clusters of 3), ovate-deltate, 0.6–2 × 0.6–1.5 mm, fleshy, apex subacute, often mucronate;

petiole 0.1–1.1 cm;

blade usually lanceolate to (narrowly) elliptic or oblanceolate, rarely narrowly obovate, (1.7–)3.1–8(–10.5) × 0.5–2(–2.5) cm, chartaceous, viscid, base cuneate or attenuate, margins entire, apex obtuse or acute, always glandular-mucronate, surfaces densely villous, sometimes less dense adaxially, distal leaves more pubescent than proximal ones;

bracts scarcely reduced.

opposite;

stipules narrowly deltate or ovate, 0.05–0.15 × 0.05–0.1 mm; submerged stems: petiole 0–0.2 cm, blade narrowly linear, 1.9–4 ×0.1–0.25 cm;

emergent stems: petiole 0–0.2 cm, blade narrowly elliptic or narrowly oblanceolate-elliptic to linear, 0.6–1.8 × 0.2–0.5 cm, base narrowly cuneate, margins entire, apex acute, surfaces glabrous or sparingly strigillose on margins and abaxial midveins;

bracts reduced.

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

bracteoles narrowly to broadly obovate, 1–1.2 × 0.7–0.8 mm, succulent, apex acute, oppositely attached at ovary base.

in racemes or spikes, well-formed on ascending stems, not on prostrate stems;

bracteoles attached at base of ovary or 1.5–8 mm proximally on pedicels, sublinear to very narrowly elliptic, 1.4–5 × 0.2–0.8 mm, apex acute, surfaces minutely strigillose.

sepals usually deciduous, not persistent on capsule, lanceolate, 6–12(–16) × 2–4 mm, chartaceous, apex acute, surfaces densely villous;

petals yellow, fan-shaped, (12–)16–20(–26) × 11–16(–21) mm, apex rounded, usually emarginate, rarely mucronate;

stamens 10(or 12), in 2 unequal series, yellow, filaments reflexed, shorter ones (2.8–)3.8–5.3 mm, longer ones (3.7–)6–6.5 mm, anthers oblong, 1–2.5 × (0.6–)0.8–1.2 mm;

ovary subcylindric, terete, 6–12 × 1.5–2.5 mm, apex thickened, densely villous;

nectary disc slightly raised on ovary apex, yellow, 1.5–2.5 mm diam., lobed, ringed with villous hairs;

style yellow, 4.7–6.7(–8) mm, glabrous or sparsely pubescent near base, stigma subcapitate-globose, 1–1.3 × 1.6–2.5 mm, usually exserted beyond anthers.

sepals reflexed or spreading, green, lanceolate-deltate, 5.2–10 ×1.5–2.7 mm, with 3 prominent parallel veins, margins entire and minutely strigillose, apex acute or elongate-acuminate, surfaces minutely strigillose abaxially;

petals rarely caducous, elliptic-obovate to spatulate-obovate, 7–11 × 4.5–8 mm, base attenuate, apex rounded;

filaments initially spreading, becoming erect, yellow, 2.5–4.5 mm, anthers 1.3–2 × 0.7–1.1 mm;

pollen shed in tight tetrads;

ovary cylindric to funnelform, 4–5.5 × 1.5–2.8 mm;

nectary disc elevated 0.6–1 mm on ovary apex, 1.5–2.6 mm diam., bright yellow, with 4 distinct domed lobes, minutely strigillose between lobes or glabrous;

style yellow, 2.3–4(–4.8) mm, glabrous, stigma yellow, broadly capitate, 0.3–0.6 × 0.6–1.8 mm, as long as or exserted beyond anthers.

subcylindric, terete, straight or curved, (11–)14–25 × 3–4 mm, with thick woody walls, irregularly and tardily dehiscent, villous-viscid, pedicel 13–25(–27) mm.

clavate, subterete, sometimes slightly curved, 5.5–10 × 2.3–4 mm, hard-walled, irregularly dehiscent, pedicel (12–)17–45 mm.

embedded in wedge-shaped piece of endocarp, 0.8–1 × 0.8–0.9 mm.

light to dark brown, elliptic-oblong, 0.5–0.7 × 0.3–0.4 mm, surface cells transversely elongate.

= 48.

= 32.