Thursday, May 2, 2013

Catkin appearance and pecan flowering habit

    Before a single grain of pollen is shed, the timing and appearance of catkins can give you a pretty good idea of the flowering habit of a pecan cultivar. As you know, pecan cultivars can have one of two flowering habits. A tree that is "protandrous" sheds its pollen before the pistillate flowers on that same tree become receptive. In contrast the pistillate flowers of a "protogynous" cultivar become receptive to pollen before the catkins produced by the same tree start shedding pollen. These flowering habits were designed by nature to ensure cross pollination and to limit self-pollination.
   In the photo above, look carefully at the shape, size, and texture of the catkins produced by the Kanza and Osage cultivars.  At this time during the season, the catkins on the protandrous Osage shoot have already grown plump with the individual pollen sacs clearly visiable. It won't be long until these catkins will begin to shed pollen. In contrast, the catkins on the protogynous Kanza shoot are narrow, not yet fully extended, and the pollen sacs still tightly bound along the catkin's stem. These catkins will release their pollen much later.

   The photo at left shows another comparison between protandrous and protogynous cultivars: this time is Chetopa Vs. Giles.  Both of these cultivars have yet to put out a lot of leaves but differences between catkin shape and texture are still evident. Catkins on the early pollen shedding Giles shoot are thicker and more course (pollen sacs showing). Chetopa catkins are thinner and smoother.
    As the season progresses, the differences in catkin size and shape become even more striking. Check out the photos from last spring.