Clonal material of the temperate C4 species Cyperus longus L. (Cyperaceae) sampled from Cornwall, S. W. Great Britain and Mt Pilion, central Greece was grown under the same environmental conditions. Comparisons were made of the pattern of leaf growth, net photosynthesis (Pn) and the characteristics of the isoenzymes of glutamine synthetase (GS). In addition, we studied the morphological characteristics of these clones and 95 herbarium specimens collected from a range of localities throughout Europe.
Principal-components analysis of the morphological characteristics suggested that European material falls into two distinct morphological groups, typical C. longus and ssp. badius (Desf.) Murb. The clonal material from Cornwall corresponded morphologically with ssp. longus and that from Mt Pilion with ssp. badius. Physiological and biochemical measurements of the two clones indicated distinct differences in the phenology, Pn and stomatal conductance at high light levels, their complements of GS1 and GS2 isoforms and associated temperature stability. It appears, therefore, that ssp. badius represents a distinct ecotype of ssp. longus. However, the apparent taxonomic distinction between the groups requires further investigation of population variation, as our studies were performed on a limited amount of clonal material.