Glabrous. Stem internodes distinctly quadrangular when young. Leaves opposite; lamina broadly ovate to cordate-orbicular, 7-19 by 5-13 cm, truncate to strongly cordate at the base, subsessile on a petiole 1-3 mm long, rounded at the apex, dull or slightly lustrous on either side; venation pinnate with the midrib and the main laterals visible on both sides. Inflorescencess at the nodes, a raceme or spike of (l-)2-5 opposite pairs of flowers; axis 4-14 mm long; pedicels 0-1 mm long; central bract orbicular, 2-2.5 mm long; lateral bracts 2-2.5 mm long, connate, together almost completely enclosing the ovary. Corolla in mature bud 6-merous, 70-125(-150) mm long, winged at about four fifths the length, clavate, often angular and truncate at the apex, red or yellow below, often yellow at the neck and red or green above; tube in the open flower 55-110 mm long with the lobes reflexed or twisted 5-10 mm higher. Anther 3-8 mm long, obtuse, about equal to the free part of the filament.
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