Teasels can be found all year, the full-grown plants often standing tall above the surrounding vegetation. They are biennials, and start off in their first spring as neat, almost flat rosettes of leaves. The tall flowering stems grow in the second year. Late July to August is the time to see the magnificent egg-shaped flower heads made up of little pinkish purple flowers and striking green bracts. The flowers open in rings round the centre of the head, eventually joining up to cover the whole surface – or sometimes not. It’s worth looking closely at the intricate patterning of the heads, and gently feeling their prickly surface. They were once used to comb out fleece ready for spinning, and to finish wool cloth by brushing it to a soft, smooth pile. Apparently some quality manufacturers were still using Teasels in preference to mechanical substitutes as late as the end of the nineteenth century – though by then they were probably using a cultivated non-native variety known as Fuller’s Teasel.
As the flowers die back and the seeds ripen, Goldfinches move in. These bright little birds love Teasel seeds and their bills are specially adapted to pick them out. Luckily they miss or drop one or two to ensure next year’s new plants. The tough dried-out stems and seed heads will stand through all but the worst of winters and you can often see last year’s dead plants alongside the newly flowering ones.
Look down the stems, and you’ll notice one of the Teasel’s most intriguing features. The bases of the leaves overlap around the stem to form a watertight cup which holds moisture in all but the driest weather. There are various theories about why this happens. Possibly it’s an extra water source, absorbed through stem and leaves to help a particularly tall plant to survive drought. Perhaps it’s a way of preventing insects from climbing the stem and attacking the flowers. Most intriguing of all is the possibility that drowned invertebrates provide an extra source of nutrients that help it to set its seeds – a sort of plant’s mineral supplement – meaning that it’s just a couple of steps away from being carnivorous. Read all about it: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017935
At St Nicks, Teasels grow in a number of locations but one of the easiest places to examine them closely is at the bottom of the Bund steps.