Chromosome Numbers of Ten Species and Clones in the Genus Psidium1

Abstract

Abstract Polyploidy within Psidium guajava appears to be uncommon but the genus Psidium is represented by di-, tetra-, hexa- and octoploid species. The species and their respective chromosome numbers are: P. guajava and P. polycarpum, 2n = 22; P. guineense and P. cujavillus, 2n = 44; P. friedrichsthalianum (El Salvador), 2n = 44; P. friedrichsthalianum (Costa Rica), 2n = 66; P. cattleianum f. lucidum, 2n = 66. Two plants of P. cattleianum were found to be 2n = 77, a heptaploid number, but whether these plants represent horticultural variants has not been established. Close resemblance in vegetative characters of the species and gross appearance of the chromosomes of P. guajava and P. polycarpum on the one hand and those of P. guineense and P. cujavillus on the other casts some doubt as to their identities.