Intersectional Hybridization in Haplopappus: Blepharodon x Hazardia

Abstract

Interspecific hybrids between H. arenarius Benth. (n = 4) of sect. Blepharodon and H. squarrosus Hook. et Arn. (n = 5) of sect. Hazardia are vigorous but only 3.8% pollen fertile. Pachytene analysis of microsporocytes shows that the chromosomes of the 2 spp. are highly homologous and differ primarily by translocations. Mean minimum chiasma frequency is reduced from that of the parents to 4.3/cell. Both morphological similarity and cytogenetic analyses indicate that the 2 sections should be considered congeneric.