QUANTITATIVE FLORAL, DEVELOPMENT IN PSEUDOLYSIMACHION (SCROPHULARIACEAE) - INTRASPECIFIC VARIATION AND COMPARISON WITH VERONICA AND VERONICASTRUM

Intraspecific variation in floral development was studied in four morp hologically distinct strains of Pseudolysimachion longifolium and two of P. spicatum. Size increase of whole buds from Living plants of P. l ongifolium was followed in absolute time. Growth rates were homogeneou s within inflorescences and within individual plants, and significantl y different between individual plants. Organ growth trajectories (plot ted as organ size over gynoecium size) differed little among individua ls of Pseudolysimachion belonging to morphologically distinct strains; variation was most pronounced in the calyx. Corolla tube as well as c alyx and corolla lobe measurements varied more during the early stages of development than near maturity, suggesting constraints on mature f lower form. In addition to intraspecific variation, floral development in Pseudolysimachion was compared with that in related Veronica chama edrys and Veronicastrum virginicum, using data from a previous study. Mature flowers of Pseudolysimachion have long corolla tubes similar to those of Veronicastrum and long corolla lobes similar to those of Ver onica. The trajectories of most organs of Pseudolysimachion were inter mediate between those of Veronica and Veronicastrum in position as wel l as in type of curve, i.e., different trajectories lead to similar en d products; thus, the shapes of the mature organs are not strictly hom ologous and not indicative of close relationship.