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CYTOGEOGRAPHY OF NYMPHOIDES (MENYANTHACEAE)
Author(s) -
Ornduff Robert
Publication year - 1970
Publication title -
taxon
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.819
H-Index - 81
eISSN - 1996-8175
pISSN - 0040-0262
DOI - 10.2307/1219284
Subject(s) - biology , ploidy , genus , chromosome number , botany , old world , chromosome , zoology , evolutionary biology , karyotype , genetics , gene
Summary Chromosome counts indicate that x = 9 in the aquatic genus Nymphoides (Menyanthaceae). New World species are tetraploid, but diploid species as well as tetraploid ones occur in the Old World. The pan‐tropical N. indica is tetraploid in the New World and diploid in the Old World, but no consistent morphological characters have been found that separate these chromosomal races. The Eurasian N. peltata is hexaploid. Self‐incompatible distyly, dioecism, and homostyly are present in the genus. The latter two breeding systems are believed to be derived from distyly. The Colombian N. flaccida seemingly occurs in the long‐styled form only and because of its self‐incompatibility may reproduce exclusively by vegetative means.