Native to south-eastern USA and Mexico, bitter weed is a compact annual with small yellow flowers.
Bitter weed is poisonous to livestock and competes with pasture and native vegetation. In Queensland, it has been found at only 1 location, near Mount Tarampa in the Lockyer Valley.
- Annual herb up to 60cm tall, compact and bushy under favourable conditions.
- Stems are smooth and branching with numerous leaves.
- Leaves are smooth, narrow, thread-like, light green to gray-blue.
- Flowers are yellow, daisy-like, about 2cm in diameter.
- Unnoticed when competing with other plants, producing a single flower on plants as small as 5cm tall.
- Prefers open fields, roadsides and disturbed areas in subhumid, warm temperate and subtropical areas where annual rainfall does not exceed 1,000mm.
Distribution in Queensland
- Only known to exist at a single location near Mt Tarampa in Lockyer Valley in South East Queensland.
- Flowers mostly over spring and summer.
- Scented flowers are pollinated by insects such as bees and butterflies.
- Mature seeds are non-dormant and germinate readily in sunlight.
- sheep; horses; cattle
- Competes with native vegetation.
- Potential weed of pastures.
- Poisonous to stock, including sheep, horses and cattle.
- Taints milk of dairy cattle.
How it is spread
- Seeds in hay, silage and on vehicles.
- Hand-pull, ensuring entire root system is pulled up.
- Broad-leaf herbicides such as 2,4-D or Grazon P+D® can be effective.
- No known biological control agents.
- This is not a declared species under the Land Protection (Pest and State Route Management) Act 2002 but may be declared under other legislation or local government law.
- Last updated
- 25 November 2015