FACTSHEETS FOR FARMERS
www.plantwise.orgCreated in Tanzania, February 2016
Ageratum conyzoides
Recognize the problem
Family: Asteraceae (daisy family).
Common names: goatweed.
Kiswahili: matawana.
Annual broadleaved herb with green, purplish or reddish stems (0.3–1 (1.5) m tall).
Stem branched and covered in short white hairs on young parts and nodes; shallow
fibrous roots.
Leaves: Bright green, sparsely hairy, rough with prominent veins, triangular to egg-
shaped (20–100 mm long and 5–50 mm wide) margins bluntly toothed with blunt or
pointed tips, in opposite pairs; hairy petioles (5–75 mm); characteristic odour when
crushed, smelling like a male goat.
Flowers: Blue to lavender, fluffy, sometimes with a white head in compact terminal
cluster bearing 4–18 flowerheads (each 4–5mm across and 4–6 mm long), with
slender, hardly exserted styles; slightly aromatic.
Fruits: Brown, small, dry and one-seeded.
Background
Origin: Latin America.
Introduction: As ornamental.
Habitat: Humid tropical and subtropical regions; grows on both light and heavy soils;
prefers most habitat but also grows in dry areas.
Spread: The seeds are mainly spread by wind and water, but are also readily dispersed
on clothing or animal fur and machines.
Invades: Croplands, plantations, pasture, grasslands, disturbed land, wasteland, urban
open space, fallow land, roadsides, railways, drainage ditches, riparian areas and
forest edges/gaps.
Impacts: This weed reduces crop yields and is an important alternate host of a number
of economically important crop pathogens and nematodes. It also readily displaces
native plant species. It excludes native grasses and medicinally important plants,
reduces native plant abundance and creates homogenous monospecific stands. The
species is an aggressive short-term colonizer of gaps in vegetation. It can become
dominant following overgrazing. In Tigray, northern Ethiopia, accidental consumption
of the seeds with sorghum was implicated in the cause of liver disease resulting in the
deaths of 27 people and numerous livestock.
Scientific name(s) > Ageratum conyzoides
The recommendations in this factsheet are relevant to: All Countries
Authors: CABI. Edited by Abdul Kudra, Fridah Mgonja
Sokoine University of Agriculture, Box 3005, Morogoro
tel: +255(0) 754 632778 email: abkudra@yahoo.com
Edited by Plantwise
Plantwise is a global initiative led by CABI
096En
Lose Less, Feed More
Ageratum conyzoides flowers have
4-18 flowerheads, 4-5 mm across.
(Photo by Arne Witt, CABI)
Leaves are triangular to egg-
shaped, up to 10 cm long. (Photo
by Arne Witt, CABI)
