Description

Key Characters:

Growth Form: Weakly erect to scandent perennial herbs.

Stems: Stems hirtellous (hairs somewhat crinkly, but spreading or rarely retrorsely appressed, 0.5–1 mm long).

Roots:

Leaves: Leaves simple. Opposite. Blades ovate, 10–14.5 cm long, 3.5–6.5 cm wide. Apex long-acuminate. Base truncate to occasionally subcordate. Surfaces hirtellous (hairs shiny, somewhat crinkly, and unequal in length), ± inconspicuously glandular–dotted; blades thin, somewhat rugose. Margins crenate–serrate or dentate–serrate. Petioles (2–)2.5–5 cm long, hirtellous (hairs rarely retrorsely appressed). Stipules absent.

Flowers: Flowers (4)6 per verticillaster, in leafy, compound, terminal, bracteate, racemose inflorescences usually 8–19 cm long, consisting of the primary branch and 2 to several lateral branches immediately below, pedicels 3-5(-9) mm long, hirtellous [hairs somewhat crinkly, unequal in length, (0.1–)0.3–1 mm long], bracts ovate to narrowly ovate, 3–12 mm long, lowermost pair larger, 15–30 mm long, bract pubescence same as that of leaves. Calyx narrowly campanulate, 4–5 mm long, enlarging in fruit, veins inconspicuous, hirtellous as the pedicels and sparsely glandular–dotted, rarely without glandular dots, 5-toothed, the teeth narrowly deltate, 1–1.5 mm long, apex acute, splitting longitudinally, usually persistent or sometimes only ventral 1/2 persistent. Corolla bilabiate, white, lobes tinged lavender, tube narrowly funnelform, usually curved, ca. 9–12 mm long, villous, upper lobe ca. 2.5–3 mm long, villous, lower lobe ca. 5–7 mm long; nectary disk often present at base of ovary, annular or developed on anterior side only. 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 ca. 2.5 mm long. Seeds with endosperm absent or scanty and oily.

Ploidy:

Habitat: Apparently rare in diverse mesic forest to wet forest.

Elevation Range: