A biosystematic study of Leptochloa with special emphasis on Leptochloa dubia (Gramineae: Chloridoideae)

Vita.Numerous taxa of genera Leptochloa, Diplachne, Bewsia, Cypholepsis, Gouinia, Kengia, Pogonarthria, Psilolemma, Trichoneura, and Tripogon were studied (1) to determine the systematic relationships of Leptochloa, (2) to establish the correct generic placement of Leptochloa dubia, and (3) to determine the extent and causes of variation in L. dubia. The systematic relationships of Leptochloa were determined by the examination of geographic distribution, habit and branching pattern, seedling characteristics, stem structure, ligule characteristics, leaf0blade anatomy and photosynthetic pathways, leaf-blade epidermis, inflorescence morphology, breeding systems, caryopsis and embryo type, and chromosome numbers. The data support congeneric status for Leptochloa and Diplachne, but Bewsia, Kengia, Gouinia, Trichoneura, Tripogon, Pogonarthria and Psilolemma are recognized as distinct genera. The incorrect placement of Leptochloa monticola became evident in this study. This species probably is a member of the Arundineae-Danthonieae group. Leptochloa dubia was found to be correctly placed in Leptochloa in spite of strong similarities with species of Kengia and Gouinia.