The southern longleaf pine is the official state tree of Alabama. The Alabama legislature first designated the state tree as "the southern pine tree" in 1949 - it wasn't until 1997 that the southern longleaf pine (Pinus palustris Miller) was specified.

The longleaf pine ecosystem once covered 90 million acres in the Southeastern United States. Today only scattered patches of the longleaf pine/wiregrass ecosystem occur - mostly in the coastal plains of the Carolinas, Georgia, Florida, Alabama, Louisiana, and Texas. Less than three million acres remain (over 97% decline) and over 30 plant and animal species associated with longleaf pine ecosystems are threatened or endangered.

Partners for Fish and Wildlife Initiative

The U.S. Fish and Wildlife Service, Southeast Region, is working with other partners to locate private landowners that are interested in restoring this endangered ecosystem and developing a habitat restoration plan for their property (read more on their Longleaf Pine Ecosystem Fact Sheet and How Can I Help pages).

Longleaf pine can grow to a height of about 150 feet and a diameter of nearly four feet. Longleaf pine is a unique tree because it develops very little above ground during the first one to five years of life (during this time it is often mistaken for grass). The longleaf pine is so named and distinguished by the needles which are about 12 inches long. (the cones are about seven inches long).

Source:

Official Alabama Tree: Alabama State Archives and History
Longleaf Pine Ecosystem: FWS-Partners for Fish and Wildlife

Links:

State Trees - 50 States List