Flowers 5-merous, white, tipped with blue or with purple veins, pale blue, or with fine blue mauve or dark blue lines, in terminal and axillary many-flowered cymes, arranged in subcorymbiform cymes; pedicels very variable; bracts 4–15 mm. long, linear-lanceolate.
Leaves in distant pairs, 20–85 x 5–20 mm., the upper sessile, the basal longer than the cauline ones, oblong to ovate-oblong, narrowed into a short petiole; the upper patent to subpatent, ovate to elliptic-lanceolate, acute or subobtuse at the apex.
Corolla with a very short tube; lobes 8–13 x 3–3.5 mm., obovate-oblong, obtuse or rounded at the apex with a pair of fimbriate nectaries within, near the base.
Stamens inserted in the sinuses; filaments 4.5–6 mm. long; anthers 1–1.5 mm. long, narrowly-ellipsoid, dark brown.
Ovary 4–5 x 2–2.5 mm., narrowly-ellipsoid, narrowed into a short stout style; stigma bilobed, papillate.
Calyx divided almost to the base; lobes unequal, 2–5 mm. long, oblong to oblong-obovate.
Stem stout, 2–6 mm. diam., unbranched or sparsely branched at the apex.
Simple or sparsely branched perennial from 6 in. to 2 ft. high
Seeds, 0.35–0.4 mm. in diam., subglobose; testa faveolate.
Rhizomatous ascending herb up to 150 cm. tall.
Capsule 7–9 x 3–3.5 mm., narrowly ellipsoid.
Mauve flowers.