The pecan tree hails from the hickory family and while its original range was in the lower central parts of the United States, the tree now grows in southern portions of the East. The pecan tree produces flavorful nuts and valuable wood. The leaves of the pecan tree are not difficult to recognize once you familiarize yourself with some of their distinct aspects.
The leaves of the pecan tree are pinnately compound. This botanical term refers to the structure of the leaf, in which several smaller leaflets are attached to a main stem, the rachis, to comprise one entire leaf. These leaflets grow from various points on the rachis. The pecan leaf's leaflets emerge opposite each other, with one leaflet by itself at the end of the rachis.
The rachis of the pecan leaf ranges in size, with some as long as a foot and others growing to be about 20 inches long. The individual leaflets, which can number between nine and 17 according to the "National Audubon Society Field Guide to Trees," are from four inches to eight inches in length, with widths that vary from one to two inches.
The pecan leaflets all have pointy ends, but their bases--where they attach to the stem--have a wedge shape or are frequently unevenly round. The leaf midribs, notes the Florida Forest Trees' website, are just a bit off-centered, so the leaf takes on a shape resembling that of a sickle. The edges of the pecan leaflet own fine serrations.
The color of the pecan leaflet is a combination of green and yellow on the leaflet's upper surface. The lower side is a much paler version of this mix. In the fall, pecan leaves will fall off the tree, but not before they turn shades of yellow. The upper surface of the leaf is usually smooth, while the undersides can have a few fine hairs on it. The stems to which the leaflets attach to the rachis are short.
Certain leaf diseases that can infect pecan leaves can change their appearance. Spot anthracnose, a disease caused by fungi, creates tiny red lesions on the top and bottoms of the leaflets. This causes holes to appear and can make the edges of the leaflets ragged looking. Lesions develop along the pecan leaflet vein and on the undersides of the leaflet in cases of pecan scab. An ailment known as downy spot precipitates white patches on the lower leaf, according to the National Forest Service site.