Pilea (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Pilea Lindley

Protologue: Coll. bot. 1: t. 4 (1821).

Family: Urticaceae

Chromosome number: x= 12

Major species and synonyms

• Pilea glaberrima (Blume) Blume, Mus. Bot. Lugd. Bot. 2: 54 (1856), synonym: P. smilacifolia (Wallich ex Voigt) Weddell (1854).

• Pilea trinervia Wight, Icon. pl. Ind. Orient. 6: 9, t. 1973 (1853), synonym: P. melastomoides (Poiret) Weddell (1854).

Vernacular names

• Pilea (En)
• Indonesia: pohpohan (West Java).

Origin and geographic distribution

P. glaberrima is known from the eastern tropical Himalaya and from Java. P. trinervia has a wide distribution, from India and Sri Lanka to Taiwan, Japan, the Philippines and Indonesia.

Uses

Some Pilea spp. are grown for their ornamental foliage, but P. trinervia and P. glaberrima constitute much-relished green vegetables in parts of Indonesia (Java, Sumatra). The leaves of these aromatic herbs are by preference eaten raw with a sauce of capsicum pepper, sometimes steamed, as a side-dish with rice. They are occasionally planted as ornamental or hedge plant.

Production and international trade

The leaves of pilea are mainly gathered from the wild. Cultivation only occurs on a small scale, mainly in home gardens. In West Java it is common on local markets, even in supermarkets.

Botany

• Robust, erect, monoecious or dioecious herbs or undershrubs, 0.5-2 m tall, without stinging hairs.
• Leaves opposite, distichous; petioles 1-10 cm long; leaf-blade oblong-lanceolate or elliptical, 5-25 cm × 1.5-10 cm, base cuneate or obtuse, apex acuminate, more or less caudate; 3 prominent basal nerves extending near to apex; cystoliths usually linear, sometimes punctate.
• Inflorescence a lax or dense, copiously branched, axillary cyme; flowers male or female; in monoecious plants the lower inflorescences bear female flowers and the upper ones male flowers; flowers white or greenish-white; male flowers usually 4(-5)-merous, stamens as many as tepals; female flowers with 3 subequal tepals.
• Fruit an achene, oblique, compressed, about 1 mm long.

P. glaberrima.

• Erect herb or undershrub, up to 1.2 m tall.
• Leaves elliptical-oblong, 6-25 cm × 2-8 cm, entire or with some remote teeth above the middle, long acuminate, glabrous; cystoliths punctate, petiole 1-5 cm long.
• Inflorescence 3-10 cm long, peduncle shorter than petiole.

P.trinervia.

• Erect herb, 1-2 m tall.
• Leaves ovate-oblong, 6-20 cm × 2-10 cm, serrate; cystoliths linear, petiole 1-6 cm long.
• Inflorescence 5-30 cm long, peduncle longer than petiole.

Both species can be found in flower year-round.

Ecology

Pilea occurs in Indonesia wild at elevations of 500-2500 m, in moist shadowed localities such as forests, forest borders, ravines and watersides.

Agronomy

Pilea is said to be not easy to cultivate, being rather specific regarding its habitat. It can be propagated by cuttings or by rooted lateral branches, but seed can also be used. Because the seed is very small, it should be sown in seed boxes and transplanted 3-4 weeks later. For optimal development of individual plants, 0.5-1 m² of space is recommended. Plants can also be spaced 20-25 cm in a row to form a hedge. Usually shoots of about 30 cm length are harvested at intervals which depend on the requirements of the local market.

Genetic resources and breeding

There are no Pilea germplasm collections or breeding programmes.

Prospects

Pilea is a popular green of localized importance, mainly gathered from the wild. Because natural stands are dwindling, germplasm collection and cultivation practices deserve more attention.

Literature

• Backer, C.A. & Bakhuizen van den Brink Jr, R.C., 1965. Flora of Java. Wolters-Noordhoff, Groningen, the Netherlands. Vol. 2. pp. 40-41.
• Ochse, J.J. & Bakhuizen van den Brink, R.C., 1980. Vegetables of the Dutch East Indies. 3rd English edition (translation of "Indische groenten", 1931). Asher & Co., Amsterdam, the Netherlands. pp. 721-723.
• Soedirdjoatmodjo, M.D.S., 1986. Bertanam sayuran daun [Growing leafy vegetables]. Karya Bani, Jakarta, Indonesia. pp. 112-116.

Authors

• U.W. Mahyar