Rotula aquatica (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Rotula aquatica Lour.

Protologue: Fl. cochinch.: 121 (1790).

Family: Boraginaceae

Chromosome number: 2n= unknown

• Philippines: takad, kulutai (Tagalog), bongtal (Iloko)
• Vietnam: rù rì cát.

R. aquatica occurs in eastern Brazil, western Africa, and from India, throughout continental South-East Asia, to southern China and the Malesian region, where it is found in Peninsular Malaysia, Borneo, the Philippines, Sulawesi and New Guinea.

In the Philippines and Thailand a stem decoction is used as a sudorific and diuretic. In the Ayurvedic system of medicine the root is well known for the treatment of urinary troubles. In Kerala (India) tender stems and leaves are used as a psychoactive agent; they are dried and smoked in combination with tobacco, or drunk mixed with coconut milk. It is said that R. aquatica provokes physical and mental stimulation and enhances thought processes.

A shrub with many elongate, terete shoots, up to 3 m tall. Leaves alternate, crowded on numerous lateral short-shoots, simple and entire, oblanceolate to oblong, 0.6-2.5 cm × 0.2-0.9 cm, base cuneate to rounded, apex obtuse and mucronate, subcoriaceous, strigose, rarely glabrous; petiole 0.5-3 mm long; stipules absent. Inflorescence a terminal, short, few-flowered cyme, bracteate. Flowers bisexual, 5-merous, pedicellate; calyx with unequal lobes, 4-5 mm long; corolla 5-7 mm long, tube 1-2 mm long, lobes rounded, pink to purplish; stamens alternate with corolla lobes, exserted; ovary superior, 4-celled, style undivided. Fruit a subglobose drupe 3-4 mm in diameter, yellowish to brownish-red, with a strongly 4-lobed endocarp breaking up into 4 single-seeded pyrenes at an early stage. Seeds oblong, without endosperm.

Rotula comprises 2(-3) species. It is closely related to Ehretia , but differs especially in the undivided style. The populations of R. aquatica in eastern Brasil and western Africa are sometimes considered a separate species: R. lycioides (Mart.) I.M. Johnst.

R. aquatica is restricted to forested lowland areas, where it grows in rocky, gravelly or sandy localities that are periodically inundated, especially along streams.

R. aquatica is not threatened by genetic erosion in view of its large natural distribution.

Research on the phytochemistry and pharmacological activities of R. aquatica has not yet been carried out, but might give interesting results because of its close affinity to Ehretia , which has shown promising pharmacological activities. The claimed psychoactive activity deserves attention in research.

247, 668, 760.

621, 1013.

• '

A.M. Aguinaldo