A Preliminary Report of the Biology of the Genus Charpentiera (Amaranthaceae)

Abstract

The genus Charpentiera (Amaranthaceae), found in the Hawaiian and Austral archipelagoes, has a structurally gynodioecious but functionally dioecious breeding system. The sex ratio varies from taxon to taxon within the genus. The sex-determining mechanism is unknown. A high rate of ovule sterility is found in all the taxa, which i~ not predicted by the pollen sterility figures reported. Data concerning seed size, pollen size, and seed germination potential are provided. Hybridization is demonstrated to occur between Charpentiera densiflora Sohmer and C. elliptica (Hilleb.) Heller. Reproductive isolation is reported for C. tomentosa var. tomentosa Sohmer and C. obovata Gaud.