• Latin name
• Family
• Common name(s)
• Synonym(s)
• Geographical distribution
• Morphology
• Biology and ecology
• Agricultural importance
• Management
• Selected references
• Contributors

Trianthema portulacastrum

Trianthema portulacastrum is a branched herb with white or pale pink to purple flowers (IRRI).

Latin name

Trianthema portulacastrum L.

Family

Aizoaceae

Common name(s)

Horse purslane, black pigweed, giant pigweed

Synonym(s)

Portulacastrum monogynum (L.) Medik., Trianthema flexuosa Schumach. & Thonn., T. littoralis Cordemoy, T. monanthogyna L., T. monogyna L., T. procumbens Mill.

Geographical distribution

South and Southeast Asia: India, Myanmar, Nepal, Pakistan, Philippines, Sri Lanka, Thailand, and Vietnam.

Rest of the world: Argentina, Australia, Colombia, Dominican Republic, Ecuador, El Salvador, Ghana, Guatemala, Haiti, Madagascar, Mexico, Nicaragua, Nigeria, Panama, Peru, Puerto Rico, Saudi Arabia, United States, and Venezuela. 

Morphology

A much-branched, prostrate or ascending annual herb up to 60—cm—tall.

Stem: green or purplish, without hairs or finely hairy; flat and thickened at nodes, fleshy, with many branches, 10—60—cm—long.

Leaf: ovate to almost circular, 1—5—cm—long with slightly wavy margins; opposite in unequal pairs, without hair, narrowed at the base to a 3—10—mm—long petiole; sheathing base inflated.

Inflorescence: usually solitary flowers, without stalks, arising from leaf axils, white or pale pink to purple.

Fruit: capsule, 3—6—mm in diameter containing 6—10 seeds, awn at tip, and opens around the middle.

Seed: rough and kidney-shaped, reddish brown to black, about 1.3—mm—long. 

Biology and ecology

Common in dryland field crops, plantations, vegetable crops, open waste places, wastelands, roadsides, gardens, upland rice, and pastures. Seedlings prefer rich and moist soil; sensitive to flooding.

Flowers about 20—30 days after emergence; propagated by seed. A single plant can produce as many as 5,000 seeds.

Agricultural importance

Can be very competitive for soil nutrients. A host in India to the chilli mosaic virus, which is transmitted by aphids, and to cantaloupe disease in Texas (USA), also a host to the parasitic weed Cuscuta reflexa.

Eaten as a vegetable and leaves are used as a diuretic. Whole-plant extracts have analgesic, antibacterial, and anti-inflammatory properties, which can be used for treating fevers, inflammatory diseases, respiratory infections, and pain.

Management

Cultural control: timely soil cultivation required for effective control as the weed is able to rapidly regrow in moist soil.

Chemical control: preemergence application of pretilachlor reported to be effective.

Selected references

Backer CA. 1951. Aizoaceae. Flora Malesiana Ser. 1 Vol 4:267-275.

Holm L, Doll J, Holm E, Pancho J, Herberger J. 1997. World weeds. John Wiley & Sons, Inc. 1,129 p.

Merrill ED. 1976. A flora of Manila. Manila (Philippines): Department of the Interior, Bureau of Science. 491 p.

Moody K. 1989. Weeds reported in South and Southeast Asia. Manila (Philippines): International Rice Research Institute. 442 p.

Moody K, Munroe CE, Lubigan RT, Paller Jr. EC. 1984. Major weeds of the Philippines. College, Laguna (Philippines): Weed Science Society of the Philippines, University of the Philippines at Los Baños. 328 p.

Pancho JV, Obien SR. 1995. Manual of ricefield weeds in the Philippines. Muñoz, Nueva Ecija (Philippines): Philippine Rice Research Institute. 543 p.

Rajendran R, Kempuchetty N, Chandrasekaran B. 1999. Weed management in dry seeded lowland rice. Madras Agric. J. 86:113-115.

W3TROPICOS at http://mobot.mobot.org/Pick/Search/pick.html.

Contributors

JLA Catindig, RT Lubigan, and DE Johnson