Surrogate mother for endangered Cupressus.

In higher plants, the embryo generally derives from the fusion of male and female gametes, although it may sometimes develop from only female cells. Here we show how the diploid pollen of the Mediterranean cypress tree Cupressus dupreziana naturally produces an embryo without fertilization that is nourished in the seed tissues of a surrogate mother, Cupressus sempervirens. This reproductive strategy of paternal apomixis, which to our knowledge has not been seen before in plants, could be an adaptation by this species in response to the threat of extinction.