heterand

Heterand refers to a botanical term describing plants that produce unisexual flowers, with male and female flowers located on separate individuals. This condition is known as dioecy. In a dioecious species, one plant will only bear male flowers (staminate) and another plant will only bear female flowers (pistillate). This contrasts with monoecious plants, where an individual plant has both male and female reproductive organs, either in separate flowers or in the same flower.

The presence of separate sexes on different plants is a significant factor in the reproductive biology of a species. It often necessitates cross-pollination, where pollen from a male flower on one plant must be transferred to a female flower on another plant for fertilization to occur. This reliance on external agents for pollination, such as wind or animals, can influence the genetic diversity of the population.

Heterandry is found across a wide range of plant families, including notable examples like holly (Ilex), asparagus (Asparagus), and Ginkgo biloba. The evolutionary advantages of dioecy are thought to include avoiding self-fertilization, which can lead to inbreeding depression, and potentially promoting outcrossing and genetic variation. However, it also presents challenges for species establishment, as a suitable pollinator and a plant of the opposite sex must be present in close proximity for successful reproduction.