A Gardeners Forum Forums General Discussion The Plants and Flowers Forum Avocado tree

The story of pollination in avocado is a remarkable one, and it makes one appreciate how hard it is to get fruit to set. Avocados have flowers that open twice, on two successive days. The first day the pistil is receptive and protrudes from the flower; the second day the pistil is no longer receptive, and the stamens shed their pollen. Here is an example of protogyny, which means that the female is mature before the male ("early female"). The consequence of this is that a flower cannot self pollinate, but requires transfer of pollen, typically by bees, from another flower, often another tree. Within avocado there happen to be cultivars that open with a receptive pistil in the morning of Day I and then reopen in the afternoon with stamens of Day 2 (A Group). Other avocados open with a receptive pistil in the afternoon of Day I and then reopen in the morning with stamens on Day 2 (B Group). Some growers take advantage of these differences and plant the two near each other, so that pollen from B (AM) can be transferred to Day 1 (AM) pistils, and Day 2 (PM) pollen can be transferred to Day 1 pistils (PM). Fortunately, flowers do not always behave so regularly, so some fruits may form on trees if some of its flowers are out of synchrony. An avocado tree typically produces a million flowers per year but only sets dozens or up to 400 fruits.