Chromosome numbers of north American Lathyrus (Fabaceae)

Chromosone counts are reported for 18 populations of eight perennial Lathyrus species endemic to North America. Included are first counts of 2«= 14 for L. holochlorus (Piper) C. Hitchc., L. delnorticus C. Hitchc., L. glandulosus Broich, L.jepsonii E. Greene subsp. jepsonii and L. vestitus Nutt. in Torrey & A. Gray subsp. vestitus, and 2 n=2 8 for L. nevadensis S. Watson subsp. nevadensis. Chromosome counts of 2n= 14 for L. jepsonii subsp. californicus (S. Watson) C. Hitchc., L. vestitus subsp. bolanderi (S. Watson) C. Hitchc., L. polyphyllus Nutt. in Torrey & A. Gray and L. sulphureus Brewer ex A. Gray agree with those reported previously. Karyotypes of diploid species are symmetrical and similar to one another. Among the species studied here there does not appear to be the reduction in chromosome size and DNA amount reported in the literature for annual, autogamous Mediterranean Lathyrus species. Lathyrus L. is a genus of approximately 1 50 species of herbaceous perennial and annual papilionoid legumes (Fabaceae: Faboideae: Vicieae). The genus is distributed primarily in temperate Europe, Asia, North America, and South America, and in North Africa (Senn 1938; Kupicha 1981, 1983). There are about 26 species of Lathyrus endemic to North America (Hitchcock 1952; Welsh 1965; Barneby and Reveal 1971; Broich 1983, 1986, 1987; Nelson and Nelson 1983; Welsh et al. 1987); chromosome numbers have been reported for 15 of these species (Senn 1938; Hitchcock 1952; Ledingham 1957; Brunsberg 1965; Raven et al. 1965; Taylor and Mulligan 1968; Love and Love 1982; Ward 1983). The purpose of this paper is to report new observations of chromosome number and morphology of species of Lathyrus endemic to North America and to place these observations within the context of the genus world-wide. Materials and Methods Seeds of native Lathyrus were collected in July of 1979, 1980, and 1 98 1 . In addition to the author's collections, seeds of L. jepsonii E. Greene subsp. jepsonii were obtained from W. Roderick (Tilden Park Botanical Garden, Berkeley, CA), of L. vestitus Nutt. in Torrey & A. Gray and L. laetiflorus E. Greene ( =L . vestitus subsp. vestitus sensu Broich, 1987) were obtained from Mary Allcott (Santa Barbara Botanic Garden, Santa Barbara, CA) and of L. vestitus from MonMadrono, Vol. 36, No. 1, pp. 41-48, 1989 This content downloaded from 40.77.167.23 on Tue, 07 Jun 2016 05:23:58 UTC All use subject to http://about.jstor.org/terms