Pilea microphylla (PROSEA)
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Introduction |
Pilea microphylla (L.) Liebm.
- Protologue: Kongel. Danske Vidensk. Selsk. Skr. 5, ser. 2: 296, 302 (1851).
- Family: Urticaceae
- Chromosome number: 2n= 36, 42, 48, 50, 60
Synonyms
Pilea muscosa Lindley (1821).
Vernacular names
- Artillery plant, gunpowder plant (En)
- Indonesia: katumpangan (Jakarta), akar nasi, jalu-jalu bobudo (Moluccas)
- Philippines: alabong (Igorot)
- Vietnam: pháo bông, lăn tăn.
Origin and geographic distribution
P. microphylla originates from South and Central America, but has escaped from cultivation and is widely spread in other tropical and subtropical regions, e.g. in Africa, Madagascar and Asia. In South-East Asia it is naturalized, e.g. long since in Java, and also in towns in Peninsular Malaysia and the Philippines, but also elsewhere. In temperate regions it is a greenhouse weed, but locally, e.g. in the United States, it occurs persistently outdoors in flowerbeds and lawns.
Uses
In Peninsular Malaysia P. microphylla plants, pounded with a little garlic and salt, have been applied to the abdomen of babies to expel worms. In the Philippines an infusion of entire plants is used as a diuretic. Numerous applications of P. microphylla in traditional medicine have been recorded for South and Central America. In Guatemala crushed plants are applied to sores and bruises, and a decoction of whole plants is used internally in Cuba as a diuretic and to treat liver and urinary inflammation, and in Jamaica as a tonic and to treat asthma. In the Grenadines the decoction is applied to children with diarrhoea.
P. microphylla is cultivated in gardens and as a pot plant, and also as a ground cover. A cultivar exists with leaves blotched white and pink.
Properties
The presence of leucocyanidin, kaempferol, quercetin, caffeic acid and ferulic acid have been demonstrated in P. microphylla leaves.
Two cytotoxic triterpenoids, epi-oleanolic acid and oxo-oleanolic acid, have been isolated from the aerial parts of P. pumila (L.) A. Gray in Korea. They exhibited cytotoxicity against cultured human tumour cell lines.
Botany
A small monoecious annual or short-lived perennial herb up to 30 cm tall, but usually smaller, often much-branched and forming mats; stems drooping or ascending when older, juicy, usually glabrous; often short side-shoots present in leaf axils. Leaves opposite, but the leaves of a pair of very unequal size, simple and generally entire, obovate to elliptical or ovate, 1-15 mm × 0.5-4 mm, rounded to cuneate at base, rounded to obtuse at apex, glabrous, with prominent cystoliths above, indistinctly veined; petiole 0.5-6 mm long; stipules minute, caducous. Inflorescence an axillary small cymose cluster 1-4 mm long, sessile or pedunculate, usually with a few male and 5-10 female flowers. Flowers unisexual, small, 3-merous, subsessile; male flowers with subequal perianth segments and 3 stamens; female flowers with unequal perianth segments and superior, 1-celled ovary. Fruit an ovoid achene 0.5-1 mm long, smooth, brown.
When shaken or moistened, plants explosively scatter clouds of pollen. The small mature fruits are actively ejected by the reflexing staminodes.
Pilea is a large genus of about 250 species and occurs in warmer regions throughout the world, except Australia and New Zealand. The Asiatic species are poorly known and in need of a revision. Pilea belongs to the tribe Lecantheae , together with e.g. Elatostema .
Ecology
P. microphylla occurs on old walls, dams, roads and pathways, in Java up to 1400 m altitude.
Management Propagation of P. microphylla by stem cuttings is easy; they root easily in a sandy propagation mixture in a closed case.
Genetic resources
P. microphylla is extremely widely spread and is still expanding its area of distribution. In many regions it is even considered a serious weed. The genetic variability is not yet well understood, but seems to be large, especially in the original area of distribution in the New World tropics.
Prospects
Research on the pharmacological properties of P. microphylla seems worthwhile because it is used in traditional medicine in areas which are far apart. Moreover, it is easy to propagate and grow, which could be advantageous for developing it into a medicinal plant to be cultivated under good management practices.
Literature
261, 334, 646, 760.
Other selected sources
62, 121, 331, 522.
Main genus page
Authors
R.H.M.J. Lemmens
