The Carline Thistle, Carlina vulgaris, also known as Silver Thistle, is a prominent species growing on the dry, chalk grassland in August. It grows to about .3m in height and has quite sharp, spiny leaves. In an open, grazed, habitat it would typically be left untouched by sheep because of this. It looks like either a dead daisy or thistle head, but is actually in full flower and is the only member of the genus Carlina in the UK. It is a biennial, meaning the plant develops during its first year and flowers in its second, so does not become very woody and re-seeds. However the flower heads are quite tough and often survive through a second winter.
The Carline Thistle is a nectar source for a wide variety of butterflies including the Brimstone, Chalkhill Blue, Gatekeeper, Marbled White, Silver-spotted Skipper, Dark Green Fritillary and the once extinct, but recently reintroduced, Large Blue. Several of these can be found on the Monkton Reserve.