flooding our orchard. But yesterday, while the sun was shining, I visited several trees on my farm and noticed that pecan pollination season has begun. Pecan trees produce two types of flowers on the same tree--male and female.
Male flowers or catkins are produced on one-year-old wood. A yellow arrow points to pecan catkins in the photo at right. If you look closely catkins, you will notice that each catkin holds numerous pollen capsules roped along a single stem. As the catkins mature, pollen capsules split open, releasing thousands of yellow pollen grains.
The female flowers or pistillate flowers are located at the terminals of this year's new growth. The red arrow in the photo above points to a cluster of pistillate flowers hidden among new emerging leaves. The female flowers of this pecan cultivar (Faith) are tipped by red colored stigmas which makes them a little easier to spot in the photo.
Each pecan cultivar has a distinctive flowering habit. Some pecan cultivars are protogynous, meaning that pistillate flowers become ready to accept pollen before the catkins on that same tree releases pollen. Other tree are protandrous, meaning pollen is released from catkins before pistillate flowers become receptive. Pecan trees have this separation in the timing of of male and female flowering to ensure cross pollination among different trees and to promote hybrid vigor of the resulting progeny.
The timing of pecan flowering is also related to a cultivar's date of bud-break. Cultivars that start the spring flush of new growth early will also start flowering early, regardless of flowering habit (protandrous or protogynous). Lets look at some examples of the bud-break effect on flowering.
With two different flowering habits and differences bud break, the pecan pollination season can usually last almost 4 weeks. Pollination is an amazing process that ushers in a new season of nut production and a time of year that I look forward to each year.