Hydrolea zeylanica (L.) Vahl

This species grows in wet ground and rice fields. It is a new record for Pakistan.

On an herbarium sheet at BM, G. T. Sampson commented that this species occurs sporadically and postulated that it was introduced as a seed contaminant of rice.

Erect or decumbent annual herb. Stem up to 50 cm long, sometimes rooting at the lower nodes, upper part of the stem glandular-pubescent, lower glabrous. Leaves alternate, lanceolate, 2-8 x 0.5-1 cm; petiole short. Inflorescence densely glandular-pubescent; flowers on short lateral racemes. Bracts leafy. Pedicel 2-8 mm long. Sepals 5, united at the base, segments imbricate; lanceolate, 5-7 mm long, glandular-pubescent, 3-nerved. Corolla blue, campanulate; petals 5, united, lobes imbricate, ovate, obtuse. Stamens 5, epipetalous, c. 3 mm long; filaments dilated at the base, 2 mm long; anthers sagittate, 1.5mm long. Carpels 2; ovary 2-celled; ovules many, placentation axile; styles 2, distinct; stigmas capitate. Fruit capsular, ovoid, 4-5 mm long, dehiscence irregular; seeds many, minute, oblong.

Herbs, erect to prostrate, sometimes rooting from lower nodes, 10-60(-100) cm tall, often branched, glabrous or pubescent, unarmed. Leaf blade lanceolate to ovate, 2-10 X 0.5-2.5 cm, glabrous or pubescent, base acute, margin entire, apex acute. Flowers in terminal panicles or clusters at branch apices, rarely solitary. Pedicel 1-3 mm, elongating after anthesis. Calyx lobes lanceolate, 4.5-8 mm, pubescent or glabrous. Corolla purple-blue or deep purple-green, 3-5 mm; tube white. Anthers scarlet. Capsule ovoid, septicidal or irregularly dehiscent, included in persistent calyx. Seeds oblong-ovoid, 0.3-0.4 mm. 2n = 18, 24.

Tropical Africa, Tropical Himalaya, India, Ceylon, east to W. & S. China, Taiwan, Malaysia.

Distribution: Tropical America, Africa and S.E. Asia.

Fujian, Guangdong, Guangxi, Hainan, Taiwan, S Yunnan [India, Indonesia, Malaysia, Nepal, Philippines, Sri Lanka; Africa, SW Asia, Australia]

200 m

Fl.Per.: October-November.

Paddies, pond margins, streamsides, open forests, swampy or inundated soil; 0-1000 m.

Nama zeylanica Linnaeus, Sp. Pl. 1: 226. 1753; Beloanthera oppositifolia Hasskarl; Hydrolea arayatensis Blanco; H. inermis Loureiro; H. javanica Blume; H. zeylanica (Linnaeus) Vahl var. ciliata Choisy; Steris aquatica N. L. Burman; S. javanica Linnaeus.