THE COMMERCIAL PISTACHIO nut tree (Pistacia vera L.), like all species of Pistacia, produces male and female flowers on separate trees. Male trees are strategically located among females in the orchard to provide pollen at the time the female flowers are receptive. Although the bloom period of the ‘Peters’ cultivar (male) generally overlaps that of ‘Kerman’ (currently the only female cultivar being planted commercially), in some years all the pollen is shed before the last of the ‘Kerman’ flowers is pollinated.