Glabrous. Stem internodes when young flattened towards the apex and 4-ridged, 2 ridges forming sharp edges and 2 forming crests on the flattened faces, terete when older. Leaves opposite or slightly displaced; lamina oblong to ovate, 4-8(-13) by 2-5.5 (-7.5) cm, truncate or shortly cuneate at the base to a petiole 2-4(-10) mm long, attenuate or acuminate and acute or obtuse at the apex, thin when dry, dull on both sides, sometimes slightly darker above; venation pinnate with the midrib and the main laterals distinct on both sides. Inflorescences at the nodes, a raceme of 3-8 opposite evenly spaced pairs of triads with the central flower sessile and the lateral flowers sessile or very shortly pedicellate; axis 25-50 mm long, lacking triads in the lower 10-20 mm; peduncles of the triads 1-2 mm long, secund. Corolla in mature bud 6-merous, 20-27 mm long, inflated at the base, slender in the middle, weakly clavate and obtuse at the apex, green or yellow, sometimes with red in the basal part; petals in the open flower separating to the inflated basal part. Anther 3-4 mm long, acute, slightly shorter than the free part of the filament.
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