Invasive Alien Species

Species Name: Alternanthera sessilis

Family Name:
Amaranthaceae
Synonym:

Alternanthera repens Gmel., non Link
Alternanthera triandra Lamk.
Alternanthera denticulata R. Br.
Alternanthera nodiflora R. Br.

Origin:
Unknown
Description:
Herb, perennial or under unfavourable circumstances short-lived, often pluricaulous, 10-100 cm long; taproots robust. Stem either erect, ascending or creeping and solid, green or reddish with transverse row of hairs at the nodes and 2 opposite longitudinal hairs. Leaves opposite, shortly stalk or almost sessile, variable in shape and size, from narrowly lanceolate to obovate, 0.8-15 x 0.3-3 cm, in wet localities comparatively large, in dry localities much smaller. Inflorescence in sessile heads, growing more cylindrical with age, bisexual, sessile, solitary in the axil of bract, subtended by 2 bracteoles, rachis densely white hairy; heads or spikes 0.5-1 cm long; bracts ovate, persistent, 0.3-1 mm long; bracteoles oblong-ovate, 1-1.5 mm long; sepals 2-3 mm long, white or purplish, glossy with green base, midrib 1, strong; stamens 5, of which 3 are with anthers; style at flowering very short, afterwards slightly lengthened. Fruit falling off with the perianth, obreniform,  2 x 2.5 mm, dark brown ; seeds glossy black, 1-1.5 mm long
Invaded Habitat:
Ditches, rice-fields, cultivated soils, gardens, waste places, swamp, tea-plantations
Distribution:
Throughout Indonesia
Ecology:
In constant or periodically humid localities, In Java occurs at 1-1 000 m altitude, in Papua 0-2 650 m altitude
References:
  1. Backer , C. A. & R. C. Bakhuizen Van Den Brink.  1965.  Flora of Java. N.V. P. Noordhoff. Groningen, Netherlands
  2. Soerjani, M.,  A. J. G. H. Kostermans & Gembong Tjitrosoepomo (Eds.).  1987.  Weeds of Rice in Indonesia. Balai Pustaka. Jakarta