|Publication Type:||Journal Article|
|Year of Publication:||1997|
|Journal:||Archiv fur Hydrobiologie|
|Pagination:||171 - 185|
A relationship between the individual size and fertility of Isoetes lacustris in the habitat centres of different lakes was found. The maximum (mean) rosette size was 202.2 cm2 and the maximum (mean) number of macrospores in a sporangium was 113.4; the minimum (mean) values were 13.8 cm2 and 30.6 spores. Further correlations between vitality and fertility parameters were established. It is suggested that the main ecological factors responsible for the differences found in the lakes are effects of climate (including water temperature and duration of seasonal growth), which cause the differences in rosette size and fertility. The percentage of individuals with fertile sporangia was lowest in the slightly humic lakes with boreal climate and short summers, and highest in the clear lakes with temperate climate and long summers. Isoetes individuals showed increased size with depth.