Preslia, Praha, 76: 97–118, 2004 97 Germination of seed of Alisma gramineum and its distribution in the Czech Republic Klíčení semen druhu Alisma gramineum a jeho rozšíření v České republice Zdenka H r oudová1, Petr Z á k r a v s k ý 1 & Olga Č e c h u r o v á 2 1 Institute of Botany, Academy of Sciences of the Czech Republic, CZ-252 43 Průhonice, Czech Republic, e-mail:
[email protected],
[email protected]; 2 Školská 1, Praha 1, Czech Republic Hroudová Z., Zákravský P. & Čechurová O. (2004): Germination of seed of Alisma gramineum and its distribution in the Czech Republic. – Preslia, Praha, 76: 97–118. The distribution of Alisma gramineum in the Czech Republic was determined using herbarium specimens, data in the literature and the authors’ own records. Comparison of records from four pe- riods (before 1900, 1901–1945, 1946–1970, 1971–2001) revealed that the total number of localities has not decreased, but the occurrence changed considerably both in terms of the localities and re- gions where the species is found. Abundant populations were observed on exposed shores of water reservoirs. It has colonized the Třeboň Basin, S Bohemia, over the last few decades. Effect of water regime, light/darkness regime and temperature on germination and dormancy was studied. A. gra- mineum is adapted to germinate in water and in the dark; germination occurs in late spring, i.e. a pe- riod of high temperature. The high variation in the germination response to particular environmental factors may be accounted for the irregular occurrence of A.