Recognize the problem
Asteraceae (daisy family).
names: Parthenium weed, false ragweed, fever weed, carrot weed, carrot grass, congress weed,
famine weed, white top.
qinche arem, kalignole; French:
Parthenium matricaire, Parthène multifide.
erect broadleaved herb, 0.5-1.5 m high; stem branched with alternate leaves, longitudinally
grooved and covered in short hairs; young plants form a basal rosette of
Pale green and covered with short stiff hairs; rosette and lower stem leaves
deeply divided and large (3-30 cm long and 2-12 cm wide); upper stem leaves
are shorter and less divided.
White small compact heads (about 5 mm across), clustered at the tips of
branches, each flowerhead has 5 distinctive "petals".
Small (1.5–2.5 mm long), each containing one seed; five in each flowerhead.
Black, two thin white scales, 2 mm long; 10-25,000 per single plant with no
dormancy period; potential to build up persistent seed bank.
Deep tap root.
As medicine, ornament
and accidentally as a contaminant.
Semi-arid, tropical, subtropical or warm temperate regions; favouring heavier
fertile soils, but able to grow on a variety of soil types from sea level up
to 2400m; particularly prolific in disturbed habitats.
By seeds with wind, water, animals, machinery, vehicles and as contaminant of
crop and pasture seed and fodder.
Crops, plantations, pasture, banks of watercourses such as drainage ditches
and streams, gardens and degraded and disturbed land.
Parthenium weed inhibits the germination and growth of other plants, thereby
reducing crop yields and displacing palatable species in natural and improved
pastures. Parthenium weed may cause severe crop yield losses (>50%).
Parthenium weed is also a secondary host for a range of crop pests. Livestock
carrying capacity may be reduced by as much as 90%. The plant also poses
serious health hazards to livestock, and can cause severe allergenic
reactions in the form of skin rashes and breathing problems in people who
regularly come into contact with the weed.
a noxious weed in Kenya in 2010
(Suppression of Noxious Weeds Act: CAP 325). The Minister of Agriculture can
compel land owners to remove it from
their land or have it otherwise removed.