Plants of South Eastern New South Wales
Ageratum houstonianum
Common name
Blue billygoat weed
Family
Asteraceae
Where found
Grassy areas, gardens, disturbed sites, wasteland, roadsides, wetlands, and along streams. Mainly Sydney area and the lower Blue Mountains. One coastal sighting from Jervis Bay.
Notes
Introduced annual or biennial herb to 1 m tall or sprawling, hairy to almost hairless. Stems cylindrical. Leaves mostly opposite each other, sometimes alternating up the upper parts of the stems, 2-7 cm long, 15-60 mm wide, both surfaces with scattered hairs, margins scalloped, tips blunt or pointed. Flower heads more or less globular, 3-8 mm in diameter, pink, blue, or mauve to purplish, with numerous florets and 0 petals, in dense clusters. Flowers most of the year, mainly Summer.
PlantNET description: http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Ageratum~houstonianum (accessed 2 January, 2021)
This identification key and fact sheets are available as a free mobile application:
