And here is another Periwinkle. Vinca major and Vinca minor were the subject of my last entry but I reckon this is Vinca difformis.
 Today I dropped in at the South London Botanical Institute to have a natter with the good people that keep the show on the road at this rather wonderful outpost of botany in Tulse Hill. I saw the starry specimen above in full flower in one of the beds at the front of the Institute.
 We mused on whether it might be a white flowered form of Vincas major or minor but V. difformis seems most likely- the flowers cut diagonally at the tip are indicative. V. difformis is known to flower from late autumn onward which is another indicator of the plant's identity.
 I also note that the one at the SLBI is not as shrubby as the Greater Periwinkle but not so prostrate as the Lesser Periwinkle. Researching the species just now I learn that V. difformis is sometimes known as the Intermediate Periwinkle, presumably a reference to being somewhere between major and minor?