Synonymes : Parthenium lobatum Buckley, Parthenium pinnatifidum Stockes, Argyrochaeta bipinnatifida Cav.
Common name : Carrot grass
Common name in Hindi : Gajjar ghas
Bangla English Hindi Urdu
Diagnostic characters
Biology
Ecology and distribution
Nuisance
Weed control
Botany
Uses/Remark
References
P. hysterophorus is an annual erected plant of green - whitish colour. It is branched and with the stems meanly hairy. It is high from 30 to 40cm, but can reach 2 m.
The leaves are alternate and profoundly cut in narrow segments.
Inflorescences are grouped by 4 or 5, in small spherical heads. The flowers of the periphery are of white colour, those of the centre white - ivory. Every head is carried by a peduncle. The set forms a great crowdedly inflorescence of small white heads.
P. hysterophorus is an annual plant. It propagates by seeds.
It is an aromatic plant, liking in the fresh, shaded and slightly wet stations.
It develops in rice fields and sometimes in the fields of young sugar cane, without forming real populations and in vegetable farming’s.
-Chemical
Glyphosate at 1.0% under non cropped area.
Habit
Erected aromatic, whitish, branched herb from 30 to 75cm in height.
Roots
Deep and thick pivot from where leave secondary roots.
Stem
Cylindrical, full, more or less fluted in striking longitudinal lines corresponding in the continuation of the central nerve of leaves. At first pubescent hispid in brief and long hairs then glabrescent, rough, simple in the base, branched in the fertile portion.
Leaves
Alternate, simple and profoundly bipinnatifid, of 11 to 15cm in length and 6 to 10cm wide. They are carried by a court petiole, corresponding to the enfeeblement of the base of the lamina around the first 3 nerves. The summit of the lamina is attenuated. Margin is profoundly lobed, in lobes linear- lanceolated and with irregular teeth. The upper leaves are entire or almost, of size decreasing towards the summit of stem and passing in the simple bracts of inflorescences. The upper face is hairless, the lower face with whitish pubescent. Pinnately veined. Nerves prominent in the lower face.
Inflorescence
Panicle terminal crowded, with the numerous hemispherical pentagonal capitulums, from 3 to 5mm in diameter and in short hail peduncle from 3 to 20mm in lengths. Bracts of the involucre oval and long from 1 to 3mm, the lower face covered with glandular hairs or hairless. 5 external flowers with ligule, female, arranged in pentagon. The ligule is white, with 5 teeth, long from 0,5 to 0,7mm and wide from 0,5 to 1mm. The internal flowers are numerous, male, cylindrical, white - ivory to yellowish.
Fruit
Akene black, ovoid, 2mm in length and 1,5mm of wide, hairy in the summit carrying a pappus of 3 or 4 membraneous scales hooked, 0,5mm in lengths.
Seedling
Cotyledons sessile rounded from 3 to 4mm in length. They are quickly caduceus.
First leaves simple, arranged in rosette, petiolated, with a lamina profoundly lobed, toothed, slightly decurrently along the petiole. Petiole and lamina with hispid hairs brief and long mixed.
- Le Bourgeois T., Jeuffrault E., Grard P., Carrara A. 2001. AdvenRun V.1.0 Les principales mauvaises herbes de La Réunion. CD-ROM. Cirad, SPV. France.
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