Chromosomal analysis and distinctive morphological characteristics of Aeschynomene denticulata (Leguminosae: Papilionoideae: Dalbergieae), a predominantly hydrophytic species from Brazil

Summary A conventional chromosome analysis was performed on root meristems of the papilionoid legume Aeschynomene denticulata Rudd to obtain the karyotype, number of SAT chromosomes, their possible relationship with the NOR regions and the description of other karyological parameters. Furthermore, the distinctive morphological characteristics of this species are illustrated and described from healthy plants grown in a greenhouse. The diploid chromosome number 2n = 20 recorded in A. denticulata confirms the basic number x = 10 common in the Dalbergioid clade. Likewise, the karyotypic formula obtained and the position and behaviour of the SAT chromosomes corroborate that Aeschynomene species have unique karyotypes and that the secondary constrictions carry the NOR regions or part of them. The morphological analysis indicated that the shape and size of the stipules, the denticulate-ciliate margins of vegetative and floral structures as well as the shape and indumentum of the fruits are reliable taxonomic characters in the identification of A. denticulata , which accompanied by a detailed chromosomal analysis will avoid confusing it with its phylogenetic sister species A. ciliata . Furthermore, the amplitude of the minimum generation time recorded here is explained in terms of nucleotypic theory.