Xanthium occidentale or Xanthium stumarium
An introduced weed first noted in Australia in the1870s.
Part 2 'Poisonous plants a plenty'
What it causes: Acute liver necrosis (diterpenoid glycosides).
The cotyledons of germinating Noogoora burr are poisonous causing acute liver necrosis in grazing animals.
Seeds germinate when the soil is moist and seedlings often emerge after rain and before other feed has grown.
The mature plant is a woody annual about 1 meter tall with broad stalked leaves. The burrs each contain two seeds in separate compartments. One germinates in the first season and the next remains dormant until the next favourable season. Flushes of germination can occur after summer storms or irrigation events, and large germination events can occur after floods in flood prone areas.