Round-headed leek flower head (4th of 5 images). Close-up of the developing flower head of the round-headed leek, Allium sphaerocephalon. The flower head consists of many tiny flowers called florets joined at the umbil at the centre of the plant. Pollen-producing anthers can be seen on the ends of filaments protruding from the florets at upper centre. A. sphaerocephalon is a medium sized perennial plant which grows in grassy places, rocks and dunes, and flowers between June and August. See photos B640/116-120 for the sequence of flower opening.