Limnophila aquatica

Stem rooting at lower nodes, then erect and up to 40 cm high, with basal part usually submerged, thick, tumid at nodes. Upper leaves opposite or in verticils of 2-3, ovate-lanceolate to oblong-lanceolate, 2.8-6.6 x 0.8-1.9 cm, rounded and semi-amplexicaul at base, acuminate at apex, finely spinulose-serrate, strongly 3-5-nerved at base, glabrous on both surfaces, punctate above; lower ones in verticils of more or less 10-12, pinnately dissected, upto 5.8 cm long, often deflexed and root-like. Flowers numerous, in terminal racemes 5-18 cm long; peduncles finely glandular-hispid. Bracts ovate to broadly lanceolate, 5-7 x 3-4 mm, subacuminate at apex, finely glandular-pubescent on both surfaces. Pedicels 2-6 mm long, finely glandular-pubescent. Calyx tube 2-3 mm long; lobes more or less equal, ovate-lanceolate, 2-3 x 0.75 mm, long acuminate, scarious at margins. Corolla tube pale greenish white to white, 7-10 mm long, puberulous without, villous within at throat; limb white or pale blue or pale mauve; lobes of upper lip broadly orbicular with a pale purple blotch at centre of each; lower lip 9-17 mm across, midlobe broader than lateral ones. Posterior filaments 2-3 mm long, anterior ones longer; anther cells horizontally placed. Style glabrous. Capsule globose, 3-4 x 2-3 mm, enclosed by longer calyx lobes, tipped by withered style, glabrous; seeds oblong-cuneate to globular, 0.5-0.7 mm long, quadrangular, muricate.