Spatial segregation by gender of the subdioecious shrub Thymelaea hirsuta in the Egyptian desert

The spatial distribution of sexual morphs of the subdioecious shrub Thymela ea hirsuta was analyzed in nine habitats in the Egyptian desert. The sexual morphs tended to segregate in the environment. Males were more common on s lope sites, while female-biased sex ratios were observed in depressions. Ne arest-neighbor analyses show that males tend to be nearest neighbors of oth er males and females are positively associated with other females. This seg regation was found only in habitats that were markedly heterogeneous for so il chemistry. In more homogeneous soils, no segregation of the sexes was ob served. The spatial segregation of the sexes of a subdioecious plant indica tes that the phenomenon can occur before a species evolves strict dioecy an d may even play a role in the process.