Endophytic fungi in Quercus cerris: isolation frequency in relation to phenological phase, tree health and the organ affected.

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.