XVI International Botanical Congess

R. flabellaris exhibits strikingly different leaf morphologies in aerial and aquatic environments. Aerial leaves have broad lobes with shallow sinuses and submerged leaves have narrow lobes with deep sinuses. Epidermal cells are convolute in aerial leaves and elongate in submerged leaves. This study examined morphological development of leaves and abaxial epidermal cells in aerial and aquatic environments in order to determine correlation between cell (shape, size and number) and leaf (size and shape) parameters. Differences between aerial and aquatic leaf shape acquisition are at the level of differential cell expansion during later stages of leaf development. There is no evidence that aerial and aquatic leaf shape differences are correlated with cell proliferation differences during development. Thus, heterophyllous leaf shape change in this species is directly correlated with differences in epidermal cell expansion and not with cell number.