Chiltern Gentian

Today we made our third visit to Houghton Regis Chalk Pit. The day started out warm and sunny and when we arrived the vegetation shimmered with the silvery-blue of thousands of male chalkhill blue butterflies - quite an amazing sight. We were also lucky enough to see several clouded yellows, although I failed to get any photographs. Rosie disturbed the one I managed to creep up on, just as I was about to release the shutter!

One of the specialities of this site is the large population of Chiltern gentians Gentianella germanica. This nationally scace species is confined to the Chiltern Hills, preferring sheltered areas with rather open structured vegetation. It's a successful coloniser of bare chalk ground in some chalk pits, and at Houghton the population must run into thousands. It's the most spectacular British gentian, and looks as though it belongs on some European mountainside.

This gorgeous plant is potentially under threat, not necessarily from man's activities, but because it hybridises with the much more frequent autumn gentian Gentianella amarella, which tends to be more competitive and often ends up as the only remaining species at a site. Fortunately, at Houghton Regis, the Chiltern gentians seem to massively outnumber the autumn gentians, so should be able to hold their own as long as there is friable bare chalk in sheltered locations.