Improved pines are descendents of plus-trees, trees selected from the wild for their superior appearance—straight trunks, strong wood, and disease resistance. Plus-trees are grafted onto established rootstock trees in a seed orchard. Close together and far from wild trees, the breeding population is contained, somewhat difficult since pines are wind pollinated. Grafted plus-trees will produce seeds that are hybrids of only other plus-trees.

The seedlings are watched carefully as they grow. Rogues, those that do not meet the standards, are removed. Only trees which grow with the standard of desired traits will be allowed to produce seed. Each generation is controlled, weeded, until no rogues are produced—only those with the desired characteristics (rust-resistance, straight-grained wood, high gum production, or fast growth). Once the lineage is established, seeds are planted in nurseries for testing on various soils and differing climates.

When the lineage of trees fits a standard of characteristics, the seedlings are put into plantation production. More than a billion improved pines are produced and planted every year on more than 2 million acres in the southern US alone. The trees in the photograph are grown strictly for extraction of one type of molecule, a polymer called cellulose.

(Compiled from: "Species: Pinus elliottii", Jennifer H. Carey, Fire Effects Information System, [Online], U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory 1992 and "Genetically Improved Pines for Reforesting Florida's Timberlands", Timothy L. White and Mary L. Duryea, Circular 1190, School of Forest Resources and Conservation, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, 1997.)