01396nas a2200133   4500008004100000245009500041210006900136260001200205300001400217490000800231520089300239100001401132856011601146       1997                        eng d00aPlant size and fertility of Isoetes lacustris L. in 20 lakes of Scandinavia: A field study0 aPlant size and fertility of Isoetes lacustris L in 20 lakes of S  c1997///  a171 - 1850 v1393 aA 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.1 aVöge, M.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0343052607&partnerID=40&md5=3be747f4cb73f24bc9d8880018c16bd101895nas a2200133   4500008004100000245013500041210006900176260001200245300001400257490000800271520135200279100001401631856011601645       1997                        eng d00aNumber of leaves per rosette and fertility characters of the quillwort (Isoetes lacustris L.) in 50 lakes of Europe: A field study0 aNumber of leaves per rosette and fertility characters of the qui  c1997///  a415 - 4310 v1393 aIsoetes lacustris L. was studied in 35 lakes in the main area of distribution (N and W Europe), plus some other lakes outside of this area, where the species is present. By using SCUBA equipment fertile plants were selected randomly and several morphological and fertility characters were studied. It was found that there was a relationship between: a) the (mean) number of leaves per rosette, and the (mean) number of spores per macrosporangium, b) the number of leaves, and the number of macrosporangia per plant. The number of spores per macrosporangium is related directly to the percentage of fertile plants in the part of the population studied. A low number of leaves per rosette is a fair indication of a low number of macrospores in a sporangium and also a low number of macrosporangia per plant, anti the low number of spores points to a low percentage of fertile individuals in the part of the population studied. It is suggested that the often rapid decline of quillwort in lakes of Central Europe may be a self-accelerating process. In the N European lakes, numbers of leaves and spores have an inverse relationship to the colour of the water. In the W European lake sites, the height of the rosettes is correlated to the Secchi depth. No relationship between plant features and water characteristics (pH and conductivity) were found.1 aVöge, M.  uhttp://www.scopus.com/inward/record.url?eid=2-s2.0-0342617829&partnerID=40&md5=e5b61ab9a7b00c72dbe6bce9554fbc2f