Description

Key Characters:

Growth Form: Subshrubs.

Stems: Stems decumbent, 0.3–20 dm long, glabrous to moderately pilose.

Roots:

Leaves: Leaves simple. Alternate. Blades lanceolate to narrowly deltate, (8–[nihoa])11–33 cm long, 2.8–11 cm wide. Apex acuminate to long-acuminate. Base cordate, sometimes base of upper leaves (especially nihoa plants) broadly cuneate. Upper surfaces glabrous or rarely sparsely short–pilose, and then especially along veins; lower surfaces sparsely to moderately pilose, or glabrous in some O'ahu and Nihoa plants. Margins usually undulate, crisped, and erose–denticulate, rarely (nihoa) subentire and apparently not crisped. Petioles 1.5–9 cm long. Stipules forming sheath or ocrea.

Flowers: Flowers numerous in diffuse, green or yellowish green, many-branched, paniculate inflorescences (12–)15–50 cm long. Flowers unisexual (and the plants monoecious), the proportions of each sex varying from nearly equal to one type strongly dominating, actinomorphic. Tepals 6, outer 3 much smaller than inner ones; staminate flowers with outer Tepals green, 2–2.5 mm long, the valves yellowish green, membranous, 3–3.5 mm long; pistillate flowers with outer Tepals green, 0.8–1 mm long, the valves yellowish green, membranous, 1.2–1.5 mm long, enlarging to 5–7 mm long and becoming cordate in fruit, venation becoming conspicuous, the faces without tubercles. Stamens 6 in staminate flowers, 1.8–2 mm long; anthers dithecal, opening by longitudinal slits. Ovary superior, 1-celled; ovule 1; styles 3; stigmas fimbriate, dry.

Fruit: Nuts trigonous; enclosed by the valves; pale brown; 2–2.4 mm long; usually slightly wider; the 2 sides of a single arm of a mature nut subparallel; the angle very narrowly acute; margins of arms without a conspicuous thickened rim. Seeds with well-developed; starchy and oily endosperm.

Ploidy: 2n = 36; 40; 60

Habitat: Mesic forest (also cliff faces and dry shrubland on Nihoa).

Elevation Range: 180–1,220 m.