Erect annual, herb, 0.2-1(-1.7) m high. Fl. green, Mar to Apr or Oct to Dec. Sand, loam, sandy clay. Weed in agricultural areas.
Alternative Names. Common Lambsquarters.
General Biology. Growth form. Herb. Life form. Annual. Reproduction. Seed. Dispersal. Birds, machinery, soil movement, wind (small distances only). Toxicity. In nitrogen-rich soils can concentrate hydrogen cyanide. Seedbank persistence. 20-40 years.
Notes. Infestations may be very dense and compete vigorously with other plants. Prefers disturbed highly organic nitrate-rich soil and requires bare ground for establishment and persistence. Flowers are hermaphrodite (have both male and female parts) and are wind-pollinated. Rain, nitrate and light promote germination. Several generations may occur in one season due to rapid growth and seed production. Strongly allelopathic, capable of reducing germination and growth of other species. Exhibits great morphological plasticity and is able to adapt to different environments including shade by delaying seed set, growing taller and having greater leaf area. Produces a high proportion of dormant seed with no special dispersal mechanism.
Additional information. History of use/introduction. Medicines, dyes, food. Similar exotic species. Chenopodium murale.
Suggested method of management and control. Manual removal, particularly when plants are young, is effective due to shallow root systems, and can be done up to stem elongation and before seeding in summer. Highly susceptible to mowing/slashing before flowering. Relatively tolerant to many herbicides and any sub-lethal rates of herbicide will result in the same high seed germination rates as unsprayed plants. Read the manufacturers' labels and material safety data sheets before using herbicides. For further information consult the Australian Pesticides and Veterinary Medicines Authority to determine the status of permits for your situation or state.
Legend: Y = Yes, regularly, O = Occasionally, U = Uncertain, referred by others but not confirmed.