The cotyledons are oval and short stalked. The first true leaves are edged with backward-pointing teeth, and the overall shape that of a rounded diamond. The leaf is a dull blue green colour and the edge may be tinged with purple.
The branched stem is smooth and hollow. The leaves are a glossy rich green and clasp the stem with rounded bases.
Flowerheads are pale yellow, 20-25mm across, and form loose clusters. Petals are reddish-grey beneath. The base of the flowerhead is flask -shaped, becoming more pronounced as it grows older.
Prickly sow-thistle Profile
|Key feature||- Leaves are glossy and have sharp prickly edges and rounded bases that clasp the stem|
- Mid yellow flowers
|Number of seeds produced per plant||5,000|
|Germination period||March-July and September to November|
|Germination depth||5 cm|
|Does it have a secondary dormancy?||Yes|
|Seed longevity||>5 years|
|Factor promoting germination||Light|
|Rate of seed decline with cultivations||High|
|Lifecycle||Plants which germinate in autumn overwinter as rosettes, producing flowers in May/june; plants germinating in spring flower in June. The latter can set seed in 10 weeks. Prickly sow-thistle only reproduces by seed and is distributed by wind|
|Geographical Location||Widespread in England and Wales|
|Soil Type||Nitrogen rich loams or nutrient rich sandy and stoney soils which are not too dry|
|Impact||Increasing found in arable rotations particularly in winter crops. Autumn germinating plants can overwinter as rosettes and flower in May, spring germinating plants flower in June|
5% yield loss from 50 plants per m2
|Resistance risk||No resistance in the UK but populations resistant to ALS herbicides in France, Norway, USA and Canada|