Aeschynanthus (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Aeschynanthus Jack

Protologue: Trans. Linn. Soc. London 14: 42, t. 2, f. 3 (1823).

Family: Gesneriaceae

Chromosome number: x= 15, 16;A. lamponga: 2n= 64,A. longicaulis: 2n= 28, 30,A. radicans: 2n= 30, 32

Aeschynanthus comprises about 150 species, and is distributed from Nepal, India and Sri Lanka, through Indo-China, southern China, Thailand and the whole of Malesia, to the Solomon Islands. The total number of species occurring in South-East Asia is not known, but about 30 species have been recorded for Borneo as well as the Philippines.

Some medicinal uses have been recorded for Aeschynanthus in Peninsular Malaysia: an infusion has been given to children as a vermifuge, and the leaves have been used to poultice boils and to treat headache. Several species are cultivated as an ornamental and also as indoor pot plant in temperate regions. This is due to their vividly coloured flowers and/or attractively mottled foliage, e.g. A. longicaulis , A. radicans and A. speciosus Hook.

Very little is known about the properties and phytochemistry of Aeschynanthus . Caffeic acid has been isolated from the leaves of A. longiflorus (Blume) DC.

A. pulcher (Blume) G. Don (perhaps only a form of A. radicans ) has been recorded as causing dermatitis, but the allergenic compounds are unknown.

Epiphytic shrubs or herbs, often scandent or drooping. Leaves opposite or in whorls, more or less fleshy, pinnately veined. Inflorescence an axillary or terminal fascicle or cyme, or flowers solitary. Flowers bisexual, 5-merous; calyx dentate to partite; corolla gamopetalous, with terete-funnel-shaped, curved tube and 2-lipped limb having 5 unequal lobes; fertile stamens 4, inserted at the base of the corolla, didynamous, exserted, staminode 1, inserted on the posterior wall of the corolla tube; disk annular; ovary superior, linear, shortly stipitate, style with broad stigma. Fruit a linear 2-valved capsule, many-seeded. Seeds ellipsoid, acutely tuberculate, often with an elaiosome, on each end with a single white hair, or on one end with a single hair and on the other with a tuft of hairs. Seedling with epigeal germination; cotyledons unequal in size; first leaves pubescent, later leaves more or less glabrous.

The flowers are probably pollinated by birds, having exserted anthers shedding pollen downwards, strong protandry and copious nectar.

Aeschynanthus has been subdivided into 5 sections. In older literature, the species are ranked in the genus Trichosporum , which is older than Aeschynanthus . However, Aeschynanthus has been conserved against Trichosporum .

The plants are usually epiphytic on trees, but they sometimes also grow on rocks.

Management Aeschynanthus can be easily grown from seed, but even more easily propagated from cuttings. In-vitro micropropagation is practised successfully with some ornamental species. Anthracnose caused by Colletotrichum gloeosporioides has been observed in cultivated A. radicans . Tobacco mosaic virus has been recorded in pot plants of some cultivated Aeschynanthus .

As is often the case in large genera, some species have large areas of distribution and are common (e.g. A. radicans ), whereas others are endemic to a small region or have been collected in a few locations. Moreover, the distribution of most species is not completely known. A large-flowered form of A. radicans has been noticed on Java.

Although Aeschynanthus is probably not much used in traditional medicine, research on its phytochemistry and biological activity is desirable. A thorough taxonomic revision of the genus is still lacking.

121, 123, 331.

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R.E. Nasution