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BiologyThis rare plant is either a biennial or short-lived perennial (2), and shows a strong fidelity for certain areas (4); it has persisted around Witney in Oxfordshire since at least 1632 (2). The species requires a level of soil disturbance so that the heavy seeds may germinate during the temporary reprise from more aggressive competitors (4), and it has benefited from scrub clearance, 2-3 year rotovating, verge cutting and even a stubble fire (2). It flowers from July onwards, sometimes into the autumn (2). Tall, multi-stemmed plants produce most flowers, and the amount of seed set is highest where bumblebees are numerous and most active (2). The seeds are able to remain dormant for a long period, and the plant can return to areas from which it has been absent for some time after hedges are cut back or the ground is disturbed (4).