Cytological relationship between Echinochloa obtusiflora stapf and the Kenyan diploid strain of E. pyramidalis (Lamk.) Hitchc. et Chase

Echinochloa obtusiflora Stapf is an annual diploid species (2n=2x=18) distributed in Northern Nigeria, East Cameroun and the Sudan. This species is characterized by the markedly obtuse apexes of spikelets and lower glumes. A cormous diploid strain was collected in Kitale, Kenya and has been treated as E. pyramidalis. These two diploids were partially self-incompatible, and intersterile. Their F1 hybrid was cormous perennial like the Kenyan diploid strain, and the spikelets and lower glumes were shortly cuspidated at the tips like those of the Kenyan strain. The F1 hybrid consistently formed 9 bivalents at MI, indicating that E. obtusiflora and the Kenyan diploid strain are the carriers of the same genome. Cytologically the Kenyan diploid strain can be recognized as a related taxon of E. obtusiflora.