Invasive Alien Species

Species Name: Ageratum houstonianum

Family Name:
Asteraceae/Compositae
Synonym:
Ageratum mexicanum Sims
Origin:
Tropical America
Description:
Annual herb, erect,  sometimes creeping and rooting at the base, up to 60 cm tall. Stem white hairy, with many ascending branches. Lower leaves opposite, long-stalked, the upper leaves alternate, short stalked; blade ovate-triangular, uppermost ones ovate, 2-10 x 1.5-5.5 cm, both surfaces sparsely hairy, the margin toothed. Inflorescence in terminal clusters of flower heads, 75-100 flowered; involucral bracts with long, short and glandular hairs; receptacles rounded without scales; all flowers the same; corolla tubular with a 5-lobed limb, blueish-violet; style with two long and far exerted arms, of the same color as the corolla. Achenes long, narrow, 5-angled; pappus 5 whitish scales
Invaded Habitat:
Fallow fields, road sides, waste places, gardens, under pine trees, tea and coffee plantations
Distribution:
Java, Sumatra as far as known
Ecology:
On dry to moist, fertile to moderately fertile soils, in the open or lightly shaded, less often on regularly cultivated fields at 200-1650 m altitude
References:
  1. Backer , C. A. & R. C. Bakhuizen Van Den Brink.  1965.  Flora of Java. N.V. P. Noordhoff. Groningen, Netherlands
  2. Everaarts, A.P. 1981. Weeds of vegetables in the highlands of Java.
    LembaGA Penelitian Hortikultura, Pasar Minggu, Jakarta.
  3. Voogd, C.N.A. de. 1950. Tanaman Apakah Ini Gerangan. Buku kecil untuk taman berkelana. N.V. Uitgeverij W. van Hoeve, Bandung’s Gravenhage (translated by Soetan Sanif)