The biosystematics of the genus Lotus (Leguminosae) in Canada. I. Cytotaxonomy

Abstract

A morphological and cytological study of native and introduced Lotus species found in Canada has been conducted on both living material and on over 600 herbarium specimens from 20 Canadian and American herbaria. Illustrations of flowers, seed, ovaries and styles, habit, and geographical distribution for each species are given. Five native species, L. denticulatus (E. Drew) Greene (annual (A), self-fertilized (S), 2n = 12), L. formosissimus Greene (perennial (P), outcrossing (O), 2n = 14), L. micranthus Benth. (A, S, 2n = 14), L. pinnatus Hook. (P, O, 2n = 14), and L. purshianus (Benth.) Clem. and Clem. (A, S, 2n = 14), and four introduced species, L. corniculatus L. (P, O, 2n = 24), L. krylovii Schischk. and Serg. (A, S, 2n = 12), L. pedunculatus Cav. (P, O, 2n = 12), and L. tenuis Waldst. et Kit. (P, O, 2n = 12) were found in Canada. Chromosome numbers are reported for the first time for L. formosissimus, L. micranthus, and L. pinnatus. Drawings of karyotypes and idiograms based on chromosome analyses are presented. Morphological observations made include style shape, pollen size and shape, seed size, number of flowers, length of standard, calyx index (length of calyx/length of calyx tube), length of peduncle, length of legume, length of petiole, and central leaflet index (leaflet length/leaflet width). Results of hydrocyanide tests on leaves of the native species were negative. The relationships of the different taxa are discussed and it is considered that both the North American and Old World species should be included in a single genus Lotus.