A Rare Alga from Stonehenge

Abstract

DURING a brief stay in England last year, towards the end of June a visit was paid to Stonehenge. It was noticed that several small holes in one of the fallen stones near the centre of the Circle contained green-coloured water, and since I am particularly interested in the flora of such small rain-water pools, permission to take samples was sought and readily granted. Water was spooned up, concentrated in a small freshwater plankton collecting net, and small quantities of the concentrate transferred to comparatively large jars. The following evening, on reaching my headquarters in Cheltenham, the samples were examined and most surprisingly proved to be very rich, active and nearly pure unialgal growths of Hæmatococcus dræbakensis Wollenweber¹. I believed then that this alga was known only from pools in granite on a small island near Drobak in Norway ; I have learnt since that there is one doubtful record from Wales.