Flora of North America species comparison

fusiform, somewhat thickened, often fascicled.

prostrate, ascending or erect at tips, terete, well branched, 20–70 cm, glabrous or, sometimes, minutely strigillose on leaf margins and inflorescence.

subterete to angled, with raised lines or narrow wings decurrent from leaf axils, (30–)50–120 cm, well branched in distal 1/2, densely erect-hirsute to sometimes glabrous.

opposite;

stipules narrowly deltate, 0.05–0.15 × 0.05–0.1 mm;

petiole narrowly winged, 0.2–0.8 cm, blades on submerged stems linear, 3.2–4.7 × 0.2–0.3 cm, those on emergent ones oblanceolate-elliptic to narrowly oblanceolate, (0.7–)1–1.7(–2) × 0.2–0.7(–1.1) cm, base very narrowly cuneate or attenuate, margins entire, apex acute;

bracts not reduced.

stipules narrowly deltate, 0.05–0.15 × 0.05–0.1 mm;

sessile;

blade closely appressed to stem, lanceolate to ovate-oblong, 1.4–5.5 × 0.4–1.2 cm, base attenuate, margins entire, apex acute to rounded, surfaces glabrous or densely erect-hirsute;

bracts usually very reduced, sublinear.

sometimes few-flowered, erect racemes, flowers paired in leaf axils of prostrate stems;

bracteoles attached in opposite pairs at base of ovary or on pedicel distally, linear, 1–3(–4.5) × 0.1–0.7 mm, apex acuminate.

leafy racemes, flowers solitary in leaf axils;

bracteoles attached in subopposite pairs just proximal to ovary base, lanceolate-linear, 2.5–7 × 0.5–1.5 mm, margins entire, apex acute, surfaces hirtellous.

sepals slightly reflexed at anthesis, ascending in fruit, light green, ovate-deltate or narrowly so, (3.5–)4–5(–6) × 1.7–3 mm, with 3 parallel veins, margins strigillose and finely serrulate, apex narrowly acute to elongate-acuminate, surfaces glabrous;

petals sometimes caducous, oblong-spatulate, 4.5–5.5 × 1.5–3 mm, base attenuate, apex obtuse;

filaments spreading, pale cream, 1.8–2.5 mm, anthers 0.7–1 × 0.5–0.7 mm;

pollen shed in very loose tetrads;

ovary obconic-cylindric, subterete or scarcely 4-angled, 3–5 × 2–2.5 mm;

nectary disc elevated 0.5–0.7 mm on ovary apex, bright yellow, 1.7–2.3 mm diam., 4-lobed, glabrate;

style cream, 1.1–1.7 mm, stigma cream, broadly capitate, 0.4–0.6 × 0.5–0.8 mm, often exserted beyond spreading stamens.

sepals narrowly ovate-deltate, (5.4–)6–12 × 2.2–4.5(–5) mm, margins entire, apex acute, surfaces hirtellous or, sometimes, glabrous;

petals cordate, 12–14 × 13–14 mm, base attenuate, apex emarginate;

filaments opaque white, awl-shaped, 2–5.5 mm, anthers 1.4–2.6 × 0.4–0.8 mm;

ovary subcuboid or globose, 3–4 × 3–4 mm;

nectary disc elevated, domed, 1–1.4 mm diam., prominently 4-lobed, ringed with stiff, spreading hairs or glabrous;

style 1.3–4.5(–5.5) mm, glabrous, stigma capitate to hemispherical, 0.9–1.5 × 0.9–2(–2.5) mm, often shallowly 4-lobed, as long as stamens, sometimes exserted beyond them.

clavate, subterete to obscurely 4-angled, sometimes slightly curved, 6–10.5 × 2.5–4 mm, hard-walled, irregularly dehiscent, pedicel (4.5–)6–15(–20) mm.

subcuboid to squarish globose, 4–6 × 4–5 mm, 4-angled, often also 4-winged, wings 0.3–1.1 mm wide, pedicel 3–10 mm.

light to dark brown, ellipsoid, 0.6–0.7 × 0.3–0.5 mm, surface cells transversely elongate.

light brown, oblong to reniform, 0.6–0.7 × 0.3–0.4 mm, surface cells elongate transversely to seed length.

= 48.

= 16.