Flora of North America species comparison

often branched, to 0.6 m. Turions present, ± brown, narrowly cylindrical, with gradual transition from foliage leaves to highly reduced turion leaves, (4–)7–12(–20)× 0.5–2(–3) mm, apex rounded to truncate;

leaves often pectinate proximally and entire to 3-fid distally, strongly appressed to axis, lanceolate to narrowly elliptic or ovate in outline, (1.5–)2–4(–6.5) × (0.2–)0.3–2(–2.5) mm;

segments 0–6(–10), longest segment 0.5–2 mm, basal segment less than or equal to 1/2 central axisof leaf, apex ± acute or rounded, brown, long-necked, ascidiate trichomes in axils present.

unbranched or 1-branched, to 0.7 m. Turions absent.

opposite or in whorls of 3(or 4), heteromorphic;

petiole 0–9 mm; submersed leaves usually pectinate, sometimes 2- or 3-lobed, ovate to widely ovate or trullate in outline, (1.3–)5–22(–26) × (0.3–)3–28(–35) mm, segments(0–)4–12(–14), distinctly alternate, lobed to linear-filiform, longest segment (0.5–)2–20(–25) mm; emersed leaves usually linear, spatulate, or 2- or 3-lobed, sometimes pectinate proximally, (1.7–)2.5–9(–10.5) × 0.3–3.5(–5) mm, segments (0–)2–8(–12), lobed to linear-filiform.

alternate, homomorphic, scalelike;

sessile; submersed leaves ovate, 0.3–1(–1.5) × 0.1–0.7 mm, margins entire; emersed leaves ovate to obovate, (0.5–)0.8–2.5(–3.3) × (0.2–)0.3–1.2(–3) mm, margins entire.

to 12 cm;

flowers usually unisexual, rarely bisexual;

bracteoles cream to stramineous, lanceolate, elliptic, ovate, or obovate, (0.2–)0.3–0.7(–0.9) × (0.1–)0.2–0.4(–0.5) mm, margins entire, irregular, dentate, glandular, or lobed.

to 9 cm;

flowers proximally pistillate, medially bisexual, distally staminate;

bracteoles cream, narrowly elliptic to ovate, (0.4–)0.5–0.8(–1) × (0.1–)0.2–0.4(–0.5) mm, margins usually entire, sometimes serrate.

sepals cream, elliptic to lanceolate, 0.5–0.7 × 0.2–0.5 mm;

petals persistent, cream, sometimes apically suffused with purple, widely oblanceolate, 1.2–2.5 × 0.7–1.2 mm;

stamens 8, filaments to 1.4 mm, anthers 0.9–1.8 × 0.2–0.4 mm.

sepals green to cream, lanceolate, 0.1–0.5 × 0.1–0.2 mm;

petals persistent, cream to pink, obovate, (0.6–)1–2(–2.3) × (0.3–)0.6–1.4(–1.6) mm;

stamens 4, filaments to 1.2 mm, anthers yellow, narrowly elliptic, (0.3–)0.7–1.6 × 0.1–0.5(–0.7) mm.

sepals and petals rudimentary or absent;

pistils to 0.7 mm, stigmas white, to 0.3 mm.

sepals green to cream, lanceolate, 0.1–0.6(–1) × 0.1–0.2(–0.6) mm;

petals often persistent, cream to pink, obovate, 0.5–1.7(–2.2) × (0.2–)0.4–1.2(–1.5) mm;

pistils to 1.3 mm, stigmas white, to 0.7 mm.

subglobose, 4-lobed.

globose, distinctly 4-lobed.

brown, obovate, 0.8 × 0.6 mm, abaxial surface rounded, minutely tuberculate, wings and ribs absent.

olive-brown, cylindric to ± globose, 0.6–1.3 × (0.2–)0.4–1.4 mm, transversely ovate, abaxial surface rounded, smooth or minutely papillate, rarely with a single obscure, longitudinal ridge, wings absent.

= [14] 21.

= 14.