Meer aandacht voor Callitriche’s gevraagd

When finding non-fruiting Callitriche most floristic investigators use to score only ‘Callitriche spec.’ The authors argue that features of pollen (which is generally present, except sometimes in fast running water) may offer a valuable help for identification of Callitriche species. Also some vegetative characteristics are discussed. In the province of Utrecht, notably C. obtusangula appeared to be far more common than was hitherto assumed.