Watercolour on paper of 'Crocus luteus, Crocus columbinus, Crocus caeruleus, Crocus albus, Crocus luteus' from 'Verzameling van Bloemen naar de Natuur geteekend door' (Collection of flowers drawn from nature) by Pieter van Kouwenhoorn. Dating from the c.1630s this leather bound album contains 46 paintings probably prepared for publication as many plant names are given in Latin, French and German. Kouwenhoorn was a glass painter working in Haarlem and Leiden in the Netherlands. He was one of the masters of the painter Gerard Dou (1613-1675).