Chromosome and Hybridization Studies of Agave

Abstract

Interspecific hybridization, paleopolyploidy, secondary polyploidy, and vegetative reproduction appear to play significant roles in the evolution of Agave and certain related genera. First chromosome counts are reported for Hesperaloe funifera and 10 taxa of Agave including two triploid and one diploid putative hybrids. All of our counts for Yucca, Hesperaloe, and Agave are in agreement with the base number, x = 30, which comprises a complement of five very large chromosomes and 25 medium to small chromosomes. All published chromosome counts of Agave have been tabulated and the roles of hybridization and polyploidy are assessed. Secondary polyploidy occurs in 26 of 48 (54.2 %) reported taxa of Agave; as yet only one-fourth of the total taxa are chromosomally known.