Leea (PROSEA)

Plant Resources of South-East Asia
Introduction

Leea van Royen ex L.

Protologue: Syst. Nat. ed. 12, 2 : 627 (1767).

Family: Leeaceae

Chromosome number: x= 12; L. aculeata: 2n= 24, L. guineensis: 2n= 24, L. indica: 2n= 20, 22, 24, L. macrophylla: 2n= 24

Major species

Leea guineensis G. Don,
L. indica (Burm.f.) Merr.

Vernacular names

Malaysia: mali-mali (Peninsular)
Thailand: katang bai
Vietnam: gối hạc.

Origin and geographic distribution

Leea comprises about 34 species, confined to the Old World tropics. Twenty-five species are endemic to Malesia (with a few extending to Queensland (Australia), Micronesia and Fiji), 1 species is found from tropical Africa and Madagascar, throughout South-East Asia to Micronesia (L. guineensis).

Uses

The roots, tubers and stems of various Leea species are mucilageous and astringent. Leaves and twigs have antiseptic properties and are used for poulticing wounds (e.g. L. aequata, L. angulata Korth. ex Miq.). In the Philippines, the leaves of L. aculeata Blume ex Spreng. (synonym Leea sandakensis Ridley) are used for purifying bad blood. In Java, the sap of L. angulata is used medicinally. In Peninsular Malaysia, the leaves of L. curtisii King (synonym Leea stipulosa Gagnep.) pounded with tobacco are mentioned as a remedy for baldness. In India, the roots of L. crispa van Royen ex L. are used for guineaworm and the leaves are applied to wounds. In some areas of India Leea is an important bee plant. Some Leea species are well-known garden and pot plants in tropical and subtropical regions e.g. L. guineensis and L. indica.

Production and international trade

Leea is only used at a local level.

Properties

L. aequata yields 0.15% essential oil on steam distillation. The essential oil inhibits the growth of Mycobacterium tuberculosis at a concentration of 10μg/ml in vitro. The oil also inhibits the growth of Micrococcus pyogenes at 100 μg/ml, and Pasteurella pestis at 50 μg/ml. Steam distillation of wood or leaves of L. guineensis also yields an essential oil, consisting of complex mixtures. The essential oil from the wood, however, differs significantly from that of the leaves; in general the wood oil contains more long chain aldehydes and phenylpropanoids, compared to the leaf oil, which is far more rich in terpenoidal compounds.

Phytochemical screening of several Leea species also showed an abundant presence of phenolic constituents such as flavonoids, leucoanthocyanidins, p-hydroxybenzoic acid, syringic acid and gallic acid which are e.g. present in the leaves of L. guineensis, L. indica, L. macrophylla and L. rubra. Tannins may also be present in appreciable amounts in some species.

Further pharmacological effects include a flavonoid sulphate (quercetrin 3-O-α-L-rhamnopyranoside-3'-sulphate) isolated from the leaves of L. guineensis which shows antioxidant activity, and an ethanolic extract of L. indica which selectively inhibits herpes simplex type 1 (HSV-1) virus at a minimum inhibitory concentration of 0.001-0.1 mg/ml.

Description

Herbaceous plants with a woody base, scramblers, creeping or erect shrubs or small trees; stems with spines or unarmed.
Leaves distichous, 1-foliolate, 3-foliolate, or 1-4-pinnate, usually imperfectly imparipinnate; petiole expanded to form a stipular structure surrounding the stem apex; stipules narrowly sheathing and subpersistent, or large, obovate and caducous.
Inflorescence a leaf-opposed cyme, lax or condensed, erect or pendulous.
Flowers bisexual, actinomorphic, 4-5-merous; calyx campanulate, lobes triangular; corolla lobes valvate in bud, apical part of each lobe joined into a keel, reflexed at maturity, basal part joined to each other and the androecium; staminodial tube with an upper portion consisting of 4-5 thickened lobes connate to each other by thinner tissues forming sinuses over which the filaments pass; ovary superior, discoidal, 4-10-locular, each locule with 1 ovule; style short, entire.
Fruit a berry, depressed subglobose.
Seed triangular-ovoid in cross-section, endosperm ruminate.
Seedling with epigeal germination; cotyledons leafy; hypocotyl elongated; all leaves arranged spirally.

Growth and development

In general flowers of Leea are pollinated by flies and the fruits are dispersed by birds. The inconspicuous, scentless flowers of the greenish-white flowered species are frequented by short-tongued bees and sylphids.

Other botanical information

Leeaceae is a monogeneric family closely allied to the Vitaceae in the order Rhamnales, separated because of the development of a complex staminodial tube joined to the corolla, the ovary locules that each have a single ovule, and its pollen morphology.

In the horticultural trade the name L. rubra is often used for the reddish-leaved forms of L. guineensis. The genuine L. rubra is not cultivated. The names L. coccinea, L. manillensis and L. sambucina are still widely used in horticulture. L. sambucina has been widely misapplied to L. guineensis in the botanical literature; the name is a synonym of L. indica.

Distinguishing some forms of L. indica from L. guineensis can sometimes only be done on the basis of the flower colour.

Ecology

The majority of the widespread Leea species are found below 100 m altitude, but a few species ascend occasionally to 1500 m (L. guineensis) or even to 1700 m (L. indica) altitude.

Propagation and planting

Leea can be propagated by stem cuttings, air-layering or by seed. It is best grown in light shade in moderately fertile and freely draining but moisture-retentive soils.

Husbandry

Leea grown as ornamental can be pruned to shape. L. indica responds well to coppicing.

Diseases and pests

In Hawaii cultivated L. guineensis is susceptible to Phytophthora meadii causing leaf spot, blight, defoliation and death of young plants, and Calonectria crotalariae causing collar rot and leaf spot. In France, Phytophthora nicotianae var. nicotianea may cause problems in L. guineensis.

Harvesting

Plant parts of Leea are collected whenever the need arises. Aboveground parts are obtained by clipping stems, whereas roots are simply dug up.

Handling after harvest

Leaves and stems of Leea used for poulticing are used fresh.

Genetic resources and breeding

All Leea species of medicinal importance indicated here have a large area of distribution, either naturally or as a result of cultivation, and do not seem to be at risk of genetic erosion. Apart from living collections in botanical gardens there are no germplasm collections or known breeding programmes of Leea for medicinal purposes.

Prospects

Too little information is available to evaluate the potential of Leea in local medicine, although the anti-viral activity looks promising. More research is therefore needed.

Literature

Ali, A.M., Mackeen, M.M., El-Sharkawy, S.H., Hamid, J.A., Ismail, N.H., Ahmad, F.B.H. & Lajis, N.H., 1996. Antiviral and cytotoxic activities of some plants used in Malaysian indigenous medicine. Pertanika 19(2-3): 129-136.
Chuakul, W., Saralamp, P., Paonil, W., Temsiririrkkul, R. & Clayton, T. (Editors), 1997. Medicinal plants in Thailand. Vol. II. Department of Pharmaceutical Botany, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand. pp. 140-141.
Council of Scientific and Industrial Research, 1962. The wealth of India: a dictionary of Indian raw materials & industrial products. Vol. 6 (L-M). Publications and Information Directorate, New Delhi, India. pp. 56-57.
Op de Beck, P., Bessiere, J.M., Dijoux, F.M.G., David, B. & Mariotte, A.M., 2000. Volatile constituents from leaves and wood of Leea guineensis G. Don (Leeaceae) from Cameroon. Flavour and Fragrance Journal 15(3): 182-185.
Ridsdale, C.E., 1974. A revision of the family Leeaceae. Blumea 22(1): 57-100.
Ridsdale, C.E., 1975. Leeaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 7(4). Noordhoff, Leyden, the Netherlands. pp. 755-782.

Selection of species

Authors

Tahan Uji