Description

Key Characters:

Growth Form: Robust, erect to decumbent perennial herbs.

Stems: Stems 9–50 dm long, glabrous.

Roots:

Leaves: Leaves simple. Opposite. Blades ovate, oblong–ovate to oblong–lanceolate, 8–24 cm long, (1.6–)2.5–10.5 cm wide. Apex long-acuminate. Base broadly cuneate or rarely subcordate. Surfaces glabrous, often red–tinged or with red veins; upper surfaces somewhat glossy; lower surfaces pale, thin and membranous. Margins serrate, rarely dentate or serrate–dentate. Petioles 2.5–7.5 cm long, glabrous. Stipules absent.

Flowers: Flowers 6(–10) per verticillaster, in unbranched, bracteate, racemose inflorescences 15–45 cm long, usually developing only terminally on branch, but occasionally with an additional pair of lateral inflorescences immediately below, pedicels slender, 5–15 mm long, peduncles stouter than pedicels, (3–)5–10(–15) mm long, bracts narrowly ovate, 10–25 mm long, rarely ciliate, lowermost pair slightly larger, 20–30(–45) mm long. Calyx obconical, 4–8 mm long, veins inconspicuous, glabrous, the teeth narrowly deltate, (1.5–)2–3 mm long, rarely ciliate, apex attenuate, splitting longitudinally, usually persistent or sometimes only ventral 1/2 persistent. Corolla zygomorphic, adaxially curved, 5–6.5 cm long, lobed nearly to base, lobes coalescent, 6–6.5 cm long, 3.5–4 cm wide, obovate–spathulate, apex obtuse, tips and outer margins slightly reflexing with age, outer exposed portion purple, purple–green or purple–yellow, inner concealed portion yellow, conspicuously veined, densely covered with gray or tan stellate trichomes especially along veins, internally yellow or purple–tinged distally, purple toward base, corolla usually becoming purplish with age, staminal column and apex of the style exserted for 1.5–2.5 cm. Stamens 4, ascending the upper corolla lip, included; filaments inserted near throat; anthers dithecal; anther sacs divaricate. Ovary superior, 2-carpellate, placentation basal-axile; ovules 1 per ovary lobe; style 1, included, arising between lobes, shortly 2-lobed, the lobes clavate; stigmatic only at apex, 1 lobe often rudimentary; stigmas 2.

Fruit: Nutlets 4–5 mm long; 1-seeded; dark green to black; drupaceous; exocarp fleshy; obovoid; margins slightly winged; obliquely attached at the connate base; spreading and exserted from calyx at maturity. Seeds with endosperm absent or scanty and oily.

Ploidy: 2n = 66*

Habitat: Occurs on very steep; rocky slopes. These sites have a windward aspect and are situated mid–slope between the upper rim of a deep valley and a perennial stream below. Soils at these sites are of typical volcanic; basalt origin; from the Wailuku Series of original shield building flows. The vegetation where <i>Hibiscadelphus stellatus</i> grows forms a mosaic of trees and shrublands with an open canopy; best characterized as Lowland Mesic Forest (Wagner et al. 1999). Rainfall averages from 12 to 1400 mm annually and the substrate is well–drained.

Elevation Range: 275–1,190 m.