Terrestrial herbs from perennial rhizomes; stems usually short (Panamanian plants practically stemless), woody when present, decumbent and rooting at the nodes, green to brown, and pubescent. Leaves opposite, decussate, equal or subequal in a pair, the blades membranous to papyraceous, dry, linear lanceo-late to oblong spathulate, usually somewhat falcate, the apex acute, acuminate, obtuse, or rounded, the base cuneate to subcordate, nearly entire or crenate serrate toward the apex, somewhat sinuate, green above, the mature leaves glabrescent, below lighter green, pubescent along the veins, stomata usually in groups, epidermal cells with nonundulating walls, the lateral veins 7-8, arching and anastomosing toward the margin and the apex; petioles lacking, with opposite blades joined by a line across the stem or short, green, pubescent. Inflorescences numerous, axillary, long persistent, pedunculate, cymose, sub-umbellate to racemose paniculate, often equalling the subtending leaf, oc-casionally shorter or longer with persistent small leaflike bracts; peduncles and pedicels slender, terete to quadrangular, green, glabrescent. Flowers actino-morphic to zygomorphic, 1 to many per inflorescence, nodding before anthesis; calyx campanulate, rounded or turbinate at the base, of 5 equal sepals connate at the base up to ?/ their length, green or rarely reddish, oblong, ovate, lanceolate or triangular, aestivation valvate, spreading in flower, in fruit erect and larger with prominent veins, persistent; corolla falling soon, of 5 petals connate from the base into a tube 1-2 times as long as the calyx, rotate or campanulate, some-times ventricose, white to blue, pink or lilac, nearly glabrous, the limb spreading, the lobes imbricate in bud, usually entire but emarginate at the apex; stamens 5 and equal or 4 with a reduced sterile staminode and often didynamous, exserted or included, the filaments free from each other but adnate to the base of the corolla tube, the anthers orbicular or oblong, free, locules dehiscent by longi-tudinal slits, confluent at the apex; disc gland lacking; ovary superior, ovoid to globose, the style curved, persistent, the stigma slightly bilobed; ovules nu-merous on both the surfaces of the bilamellate placentae. Fruit a capsule in-cluded in the persistent calyx, oblong, ovoid or globose, 2-or 4-valved, the valves not persistent after dehiscence, the seeds light to dark brown, striate, shiny, ellipsoidal, the embryo straight.
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Terrestrial, caulescent, decumbent herbs, without modified stems. Stems unbranched. Leaves opposite, equal or subequal in a pair, venation pinnate, stomata usually in groups, foliar nectaries absent. Flowers axillary, 1 to many in pedunculate, subumbellate to racemose-paniculate cymes; bracteoles small, persistent, leaf-like; pedicellate. Calyx lobes connate at base up to half their length; corolla white to blue, pink, or lilac, rotate or campanulate, sometimes ventricose; stamens exserted or included, filaments not connate, anthers free, dehiscing by longitudinal slits, thecae divergent; staminode present (when fertile stamens 4); disc absent; ovary superior, stigma slightly 2-lobed. Fruit a dry, loculicidally and septicidally dehiscent, light brown capsule, 4-valved, valves opening slightly.