Chromosome numbers of selected species of Elatine L. (Elatinaceae).

The paper reports chromosome numbers for 13 taxa of Elatine L., including all 11 species occurring in Europe, namely E. alsinastrum , E. ambigua , E. brachysperma , E. brochonii , E. californica , E. campylosperma , E. gussonei , E. hexandra , E. hungarica , E. hydropiper , E. macropoda , E. orthosperma , E. triandra originating from 17, field-collected populations. For seven of them ( E. ambigua , E. californica , E. campylosperma , E. brachysperma , E. brochonii , E. hungarica , E. orthosperma ) the chromosome numbers are reported for the first time. With these records, chromosome numbers for the whole section Elatinella Seub. became available. Although 2 n = 36 was reported to be the most common and the lowest chromosome number in the genus, our data show that out of thirteen species analyzed, six had 36 chromosomes but five species had 54 chromosomes, and the lowest number of chromosomes was 18. These data further corroborates that the basic chromosome number in Elatine is x = 9.