Shepherd’s purse (Capsella bursa-pastoris)
Height x spread: Up to 35 x 25cm (14 x 10in).
Leaves: Grey-green, long and narrow, variably toothed or lobed along the edges, all in a ground-level rosette.
Flowers: Tiny, white, in a tall upright spike, all year.
Other features: Small purse-shaped seed pods. Can carry club root disease. Annual.