STEMLESS THISTLE Farmers are required to control this weed.
Method of reproduction and dispersal
With a large feathery pappus, the seeds of the stemless thistle are well adapted for wind dispersal. Aided by prevailing winds, seeds have been dispersed over 200 m.
Dispersal also occurs when seeds contaminate agricultural produce, vehicles and animals. However, this dispersal method is of minor importance compared with wind dispersal. Seed is also spread via birds, in hay, silage, chaff and commercial seed and by water.
Seedbank propagule persistence
Stemless thistle can reproduce as either an annual or biennial. It produces eight flower heads per plant with 150 seeds per head resulting in 1,200 seeds per plant.
Stemless thistle seed can survive in the soil for several years making eradication difficult. Plants cut below the surface with cultivation equipment may re-sprout from root fragments, commonly producing multiple crowns.
Preferred habitat - Stemless thistle prefers warm-temperate regions typically in areas receiving less than 450 mm of annual rainfall; more prevalent on sandy soils but also occasionally appears on heavier calcareous soils. It is drought tolerant and found mainly in pastures, roadsides and neglected areas.
Growth calendar - The icons on the calendar below represent the times of year for flowering, seeding, germination, the dormancy period of Stemless thistle and the optimum time for treatment
Stemless thistle will establish in Mallee shrubland, lowland grassland and grassy woodland.
Pictured far below: Table showing growth calendar