Flora of North America species comparison

often branched, to 3 m. Turions absent.

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.

mostly in whorls of (3 or)4(or 5), sometimes opposite to subopposite, heteromorphic;

petiole 0–4 mm; submersed leaves pectinate to lobed (basalmost leaves opposite to subopposite, reduced, margins entire), ovate to obovate in outline, (3–)5–25(–35) × (2–)3–18(–20) mm, segments (2 or)3–9(–11), linear, ± applanate, longest segment (7–)8–15(–17) mm; emersed leaves pinnatisect to lobed or entire, ovate to oblong in outline, 2–9 × 1–6 mm, margins dentate to minutely serrate.

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.

to 8 cm;

flowers proximally pistillate, medially bisexual, distally staminate;

bracteoles cream, deltate, 0.5–1 × 0.2–0.6 mm, margins dentate to serrate, with glandular tip.

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.

sepals green to cream, ovate to deltate, (0.2–)0.3–0.5(–0.7) × (0.1–)0.2–0.4(–0.5) mm;

petals persistent, ± purple, oblong, 2–3 × 0.5–1.5 mm;

stamens 8, filaments to 0.6 mm, anthers 1.8–2.5 × 0.2–0.6 mm.

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 cream, deltate, 0.2–0.5 × 0.1–0.4 mm;

petals ± persistent, cream, ± cucullate, elliptic, 0.1–0.5 × 0.2–0.3 mm;

pistils 1.1–2.2 mm, stigmas cream to ± purple, to 0.6 mm.

sepals and petals rudimentary or absent;

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

cylindric to oblong, 4-lobed.

subglobose, 4-lobed.

tan to olive-brown, cylindric to ovoid, 1.5–1.8 × 0.6–0.8 mm, transversely elliptic, abaxial surface rounded, smooth, sometimes with a shallow, longitudinal ridge, wings and ribs absent.

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

= 42.

= [14] 21.