The cytology of thirteen taxa and two hybrids in the genus Pennisetum indicated the distribution of the taxa among the four basic chromosome numbers 5, 7, 8 and 9. The diploid nature of P. ramosum and P. typhoides and the genomic allotetraploid status of P. purpureum was further confirmed. P. massaicum (2n=32), P. orientale (2n=36) and P. subangustum (2n=36) suggested probable autotetraploid nature and the three hexaploids (2n=54) investigated (P. polystachyon, P. longistylis and P. squamulatum) revealed allohexaploid constitution. The natural triploid, P. ruppellii (2n=27) and pentaploid P. villosum (2n=45) were found to be apomicts and they were allotriploid and allopentaploid respectively. The tetraploid-hexaploid complex of P. pedicellatum showed them to be cytotypes only. The cytogenetical behaviour of the hybrid, P. typhoides x P. purpureum with 2n=21 and the trispecies hybrid (P. typhoides x P. purpureum) x P. squamulatum with 2n=48 brought out the homology within the genomes of x=7 and x=9 and also between the genomes with x=7 and x=9. The significance of the inter- and intragenomic chromosome pairing had been brought out from the interspecific hybrids and the natural allotriploid and allopentaploid species having one genome in the haploid condition.
The morphological sections of this genus did not correspond with the cytological groups. A high degree of evolutionary specialization was evident in species of the section Gymnothrix. A complete series of polyploids and high degree of heterogeneity from the morphological point of view was brought out in species with x=9.
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Sree Rangasamy, S.R. Cytological studies on diploid and polyploid taxa of the genus Pennisetum Rich. Genetica 43, 257–273 (1972). https://doi.org/10.1007/BF00123633
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DOI: https://doi.org/10.1007/BF00123633