Cortaderia (Gramineae): Interspecific hybrids and the breeding systems

Abstract

Interspecific hybrids between New Zealand decaploid species of Cortaderia (Section Bifida) are fertile and share a common gene(s) for control of male sterility, the determinant of their gynodioecious breeding system. The interspecific hybrid between the two sexually reproducing species of Section Cortaderia is F1 fertile, but shows some slight degeneration in later generations especially through lethal albinism. They share a common gene(s) for male sterility control. Experimental intersectional hybrids are nonoploid and sterile. F1 C. araucana × C. toetoe consisted of a family of solely female plants with the androecial morphology of the female parent. Such hybrids share the two main characteristics of the several apomictic taxa in Section Cortaderia; intersection hybridisation is a possible pathway towards the evolution of solely female taxa. F1 C. toetoe × C. selloana segregated plants of both sex-forms. Different male sterility genes, or alleles, occur in the two Sections, and ratios of hermaphrodite to female plants are intersectionally discrete.