In regions where substantial ?overproduction'' of food crops has occurred, farmers have sought to diversify into non-food production and many plant species have been suggested as possible new crops. An example is evening primrose (Oenothera spp.), which has become established as a high value oilseed crop for temperate regions. The seed is an important source of gamma-linolenic acid, a relatively rare fatty acid with value as a pharmaceutical and nutritional supplement. This volume begins with a general review of the principles of crop physiology, including sections on crop canopy structure and light interception, crop photosynthesis and radiation conversion, crop productivity and biomass partitioning, and factors affecting seed lipid content. It then presents the results of field and controlled environment research on the productivity, canopy development and resource use of evening primrose. Amongst other findings, these results show why, despite a long growing season, evening primrose seed yields are much lower than the yields of major arable seed crops, and why commercial spring-sown evening primrose crops can yield as much as overwintered ones.