Two New Basic Chromosome Numbers in the Genus Pennisetum

Abstract

Two basic chromosome numbers, 7 and 9, have so far been reported for members of the genus Pennisetum, which belongs to the tribe Paniceae of Gramineae¹. We recently recorded the somatic chromosome numbers 10 and 32 in the species Pennisetum ramosum C. Sm. and P. massaicum Staf., which suggests two additional basic numbers, 5 and 8, for this genus. Both P. ramosum and P. massaicum are natives of tropical Africa and are perennials with profusely branched culms. Both possess all the key characters of the genus Pennisetum. Thus, the spikelets are solitary and are surrounded by an involucre of bristles that are free except at the very base. The first glume is shorter than the spikelets; the second glume is almost equal to the sterile lemma in size and the fertile lemma is smooth with a thin margin enclosing the palea.