Erect Hygrophila is an erect or ascending annual herb, growing up to 1 m tall. Stem roots at the lower nodes. Leaves are arranged decussately opposite, simple, linear-oblong to elliptical-oblong or elliptical-obovate, 1-16 x 0.5-5 cm, narrowing into petiole at base. Margin is entire to wavy and irregularly marked with cystoliths. Stipules are absent. Inflorescence is a dense axillary cluster and conspicuously bracteate. Flowers are bisexual. The sepal is 0.6-1.2 cm long and with unequal linear- lance-shaped lobes. The petal is with ventricose, .7-1 cm long hairy tube, 2-lipped where the upper lip is about 5 mm long and divided into 2, while the lower lip is about 5 mm long and pale violet-blue or whitish. There are 4 stamens, below the middle of the petal tube. Fruit is a linear- oblong to linear-ovoid, 1-2 cm long, many-seeded capsule. Erect Hygrophila has a wide area of distribution: from India and Sri Lanka to South-East Asia.