Light micrograph of the vein pattern of a New World endemic, <em>Flaveria triner
Athena McKown University of Toronto Department of Botany 25 Willcocks St. Toronto Ontario M5S3B2 Canada
Light micrograph of the vein pattern of a New World endemic, Flaveria trinervia (Spreng.) C. Mohr., a pantropical weedy C4 species. Flaveria is of special interest because of its diversity in photosynthetic types; it has species classified as having C3, C4, or intermediate photosynthesis. This clearing of a mature leaf of F. trinervia, viewed with differential interference contrast optics, shows a reticulate pattern with high vein density and distinctive bundle sheath tissue. These two features are part of a critical suite of anatomical characteristics (Kranz anatomy) that has evolved independently many times to support C4 biochemical functioning; many variations of Kranz anatomy exist, especially in the eudicots.