Botany

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"Pecan" is a Native American word of Algonquin origin that was used to describe nuts requiring a stone to crack. The history of pecans can be traced back to the 16th century, originating in central and eastern North America and the river valleys of Mexico. George Washington and Thomas Jefferson planted pecan trees in the 1700s. Washington called them Mississippi nuts. Pecan trees can be magnificent, usually ranging in height from 70 to 100 feet but sometimes growing to 150 feet or more. Native pecan trees over 150 years old may have trunks well over 3 feet in diameter.

Pecan is a member of the genus Carya, i.e. the hickories. In depth taxonomic information on pecan and other hickories can be found at http://extension-horticulture.tamu.edu/carya/species/index.htm.

An understanding of the pecan tree's anatomy and its flowering habit is important to understanding how to provide for the tree. Pecan trees are monoecious, i.e. they have male and female flowers on the same tree, but at different locations. The male pecan flower, the catkin, provides the pollen. The female flower, the pistil forms the nut. The pecan flower cluster consists of many pistils, each capable of forming a fruit containing a seed, i.e. nut. The number of pistils in a flower cluster is influenced by the cultivar and growing conditions.

Pecan trees are dichogamus, i.e. the tree's pollen shedding and pistil receptivity occur at different times. Therefore, pecan trees require pollination by a different cultivar or a native tree. Even if a particular cultivar sheds pollen at the same time that its pistils are receptive, research has demonstrated that more fruit aborts and nuts are smaller if the flowers are self pollinated rather than cross pollinated.

Pollen shedding in relation to pistillate flower receptivity of a single cultivar is referred to as protandrous, meaning that the pollen is shed before the pistil is receptive, or protogynous, when the pollen is shed after pistil receptivity. Oklahoma Cooperative Extension Service cultivar suggestions refer to these as early (protandrous) or late (protogynous) pollen shedders. Literature from other sources may refer to protandrous as type 1 and protogynous as type 2.


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