Apomixis and Polyembryony in Hierochloe odorata

Norstog, Knut. (Wittenberg U., Springfield, Ohio.) Apomixis and polyembryony in Hierochloe odorata. Amer. Jour. Bot. 50(8): 815–821. Illus. 1963.—Hierochloë odorata from Michigan, having 2n = 56 chromosomes, was found to reproduce by pseudogamous fertilization of diploid aposporous embryo sacs. Diploid embryos, 2n= 56, and 5n = 140 ± endosperm occurred together. Megasporogenesis was incomplete, and aposporous embryo sac initials developed directly into 8-nucleate Polygonum type embryo sacs. Microsporogenesis was irregular with univalent, bivalent and multivalent chromosomes in meiosis-I. Dyads and microspores varied between n = 24 and n = 32, and less than 50% of the pollen grains stained with acetocarmine. Two other races of H. odorata are known to occur in North America. They are an apparently infertile type in Canada with 2n = 28, and a perfectly fertile race from coastal Connecticut also with 2n = 28. It is suggested that the H. odorata with 2n = 56 is a derivative of the sterile Canadian race.