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.

usually unbranched, to 6 m. Turions present, ± dark green, cylindrical, with gradual transition from foliage leaves to reduced turion leaves, 12–40(–45) × (3–)5–12(–15) mm, apex ± rounded;

leaves pectinate, stiff, strongly appressed to axis distally, not proximally, elliptic in outline, 5–15 × 1.4–5 mm, with clusters of brown, conical trichomes between leaf bases;

segments 13–15(–17), elongate botuliform, longest segment 1.8–5.2(–6) mm, basal segment usually less than or equal to 1/2 central axis of leaf, apex apiculate, with single, brown, conical trichome in each axil.

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.

in whorls of (3 or)4, heteromorphic;

petiole 0–4 mm; submersed leaves pectinate, usually obovate in outline, (2.8–)13–32(–44) × (2.1–)16–35 mm, segments 6–18(–24), linear-filiform, often perpendicular to central axis, basal segments often as long as leaf axis, segments often irregular in orientation, not parallel and not in same plane, longest segment 2–20(–26) mm; emersed leaves, basal sometimes pectinate to pinnatifid proximally, with abrupt transition to obovate, elliptic, sometimes distally spatulate, in outline, margins of distal leaves entire to serrate to shallowly lobed, 1–2.3 × 0.6–1(–1.5) mm.

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 15 cm;

flowers proximally pistillate, medially bisexual, distally staminate;

bracteoles cream to stramineous or purple with distinct, reddish or brown margin, usually ovate to depressed-ovate, sometimes elliptic to triangular, (0.4–)0.6–1.3 × 0.3–0.7 mm, margins entire or serrate, sometimes with distal, irregular, membranous fringe.

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 to stramineous, usually depressed-ovate, sometimes ovate to triangular, 0.2–0.4 × 0.2–0.5 mm;

petals caducous, cream to red or dark purple, oblong to elliptic or obovate, 1.7–2.3(–3) × 1–2 mm;

stamens 8, filaments to 1.5 mm, anthers greenish cream to yellow or purple, 1–2.2 × 0.3–0.7 mm.

sepals and petals rudimentary or absent;

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

sepals cream to green to purple, lanceolate to deltate or ovate, 0.1–0.3 × 0.1–0.2 mm;

petals often persistent, cream, widely ovate, 0.3–0.5 × 0.2–0.5 mm;

pistils 1–2 mm, stigmas white to red or ± purple, ± pulvinate, 0.2–0.4 mm.

subglobose, 4-lobed.

globose, 4-lobed.

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

olive-green to brown, cylindric to narrowly ovoid, 1.5–2.7 × 1.2–1.6 mm, transversely widely obovate, abaxial surface broadly rounded, sparsely and irregularly tuberculate, margins smooth or tuberculate, sometimes with 2 shallow, partial, longitudinal ridges, wings and ribs absent.

= [14] 21.

= 42.