Herb or low suffrutex 1-6 dm high, the roots usually fibrous; stems slender, simple or branched, glabrous or rather sparsely pilose distally in strips down each side (often along the margins of sulcae), the proximal portion often creeping. Leaves at the apex whorled, imperfectly whorled, or opposite, additional cauline leaf-pairs usually present; blades lance-ovate or lance-elliptic, infrequently lanceo-late or narrowly elliptic-lanceolate, apically acute or subacuminate, basally cuneate to subtruncate or rounded, often decurrent along the petiole, 2-10 cm long, 0.8-4.5 cm broad, membranous, glabrous or with scattered pilose or mammillate trichomes above, occasionally minutely puberulent below on the main veins; petioles ex-tremely variable, obsolete to 15 mm long. Spikes 1(2), terminal, usually simple, 3-13 cm long, 6-35-flowered, occasionally overtopped by floriferous branches. Flowers with pedicels obsolete to 1-mm long; calyx-lobes glabrous or glabrate, subulate, free to the base, equal or subequal, 2-4 mm long; corolla slender-funnel-form (sometimes rather abruptly expanded above), white, often tinged with pink, glabrous, the tube 9-19 mm long, 1 mm broad at the base, 3-7.5 mm broad at the neck, the lobes ovate or deltoid-ovate, 3-4 mm long; anthers well-included, 1-1.5 mm long, very slender, the free-portion of filaments ca 2 mm long, attached to the co-rolla-tube above the middle; style included (the tip extending to or just beyond the location of the anthers), puberulent on the upper portion, approximately the upper 1/2 enlarged and deciduous. Capsules smooth externally (not muricate), 4-6 mm broad, 2.5-4 mm long, the persistent cupular base rounded to truncate or emarginate at each end, centrally foveate; seeds brownish, ovoid, carnose, ca 1.5 mm long, often reticulate or tuberculate on the surface.
Home