This is the tree that built South Florida, and the scientific name tells you why: Pinus elliotti var. Densa. As in dense. The wood that is harvested from what's commonly called the South Florida slash pine is incredibly hard and durable.
Slash pines are found throughout the southeastern United States, including all of Florida. South Florida slash pines are only found in the southern half of the Peninsula. Find a home in the region, one built in the 19th or early 20th century, and chances are pretty good that it was built from this stuff. It's one of three pines native to South Florida, the others being sand pines, typically found in scrubs near the coast, and long-leaf, which is rare enough here that the Institute for Regional Conservation considers to be imperiled. It is plentiful elsewhere, however.
South Florida slash pines, also known as Dade County pine, are easily identifiable at a glance. Their trunks are fairly straight; mature trees are sort of lollypop shaped with branches and needles concentrated near the top of the tree; they lose their lower branches as they get older, likely an adaptation to fire. The bark is coarse, with large, orange and brown scales; the needles are seven to 12 inches long and mostly come in packets of two. South Florida slash pines can approach heights of 60 feet, with a trunk diameter of two feet or more. They can live two hundred years or more.
South Florida slash pines differ from their slash pine cousins (Pinus elliotti var. Elliotti, also called Honduras pines, in at least four ways. South Florida pines go through a grass stage as seedlings, so called because they pines resemble grass. Ordinary slash pines don't.
As noted above, the needles on South Florida slash pines mostly come in bundles of two; Ordinary slash pines have needles that are bundled in twos or threes. The wood of the South Florida slash pine is far superior in most ways, and as seedlings and saplings, they're more fire resistant because their bark is thicker. Ordinary slash pines, however, have one thing on their Densa cousins: they can approach 100 feet tall.
In a way, South Florida slash pines are almost too tough for their own good. The secret to their durability is resin, and the older the tree the more resin it has. Old growth forests provided the best lumber, but they've been cut down to the point that the only places where they're found today is in the region's parks and preserves.
South Florida slash pines like moist to wet places, and tend to form open woods. The flowers are green, turning brown and appear in winter and spring, producing cones that open up in the fall and drop their seeds. Slash pines produce both food and cover for birds and other wildlife, and their large-diameter trunks are especially important for birds that nest in cavities. The Seminoles used slash pines to meet a variety of needs beyond construction. They used bits of wood and bark to make a pain reliever. They used it to treat sores and hemorrhoids, to make baskets and to make a glue used to attach arrowheads to arrow shafts.
South Florida slash pines are members of Pinaceae, the pine family.