The very first female flowers on pecan trees are starting to emerge from this season's new growth. At this time of year, the male flowers of pecan, or catkins, are the most noticeable flowering structure on the tree. In the photo above, you see numerous catkins hanging down from last year's growth (grey twig).
From the end of last year's growth, a single new shoot has grown 4 to 5 inches in length. If you look carefully at the very tip of the new shoot growth, you'll find the female, or pistillate, flowers (photo at right). At this point the pistillate flowers are not fully formed and are extremely small. The photo below is a closeup of an emerging pistillate flower cluster. Pecan female flower clusters usually contain 3 to 6 pistillate flowers arranged along a single stem (botanically called a spike). A single pistillate flower can be seen at the end of the arrow marked "A".
It is important to remember that the number of catkins produced by a tree is not an indication of the size of this year's nut crop. It is the number of pistillate flowers produced on a tree that determines potential yield. A full crop occurs when at least 65% of new shoots produce pistillate flowers.