The Dry Tortugas are a group of seven islands, about 70 miles west of Key West, Florida. According to the U.S. National Park Service, the islands are part of the third largest barrier reef in the world. The Dry Tortugas enjoy a subtropical climate, with mild winters and hot, humid summers. Home to many species of plants, marine life and migrating birds, the islands are also a popular tourist attraction and nature preserve. Countless varieties of plants will grow here, but only a few are native.
Look for coconut palm (Cocos nucifera) and you won't have to look far. They're everywhere on the Dry Tortugas, from the shore, where coconuts have beached and sprouted, to gardens where they're planted. The most easily recognized of palms, the coconut palm reaches a height of 80 to 100 feet, with a a single crown of 20-foot-long fronds at the top that covers clusters of coconuts. The tree will often lean, because of the instability of its roots in the sand. Coconut palm has a graceful form that many people associate with the tropics.
Study the form of a banyan tree and you might get lost. This member of the fig family produces long aerial roots from its branches. They dangle down toward the soil until they reach it, then root, forming a marvelous, marching tangle of new trunks with smooth, gray bark. Banyan grows aggressively in high-humidity environments like the Dry Tortugas, so much so that they can be considered invasive. Still, their unique growth habit is endlessly interesting, and banyan is a favorite specimen tree in botanical gardens.
Walk along the estuaries of the Dry Tortugas and you'll find mangroves. This tree has uniquely adapted to the high salt concentrations in coastal mud. Long, aerial roots that seem like stilts support thick foliage on trees that grow to a height of about 20 feet. Mangroves play a critical part in soil stabilization in areas where erosion from tides is a problem. Their canopies provide shelter for birds, and mangrove roots are important nesting areas for fish and aquatic animals.
Banana plants can also be found in profusion on the Dry Tortugas. The climate is perfect for this interesting plant, which grows to a height and spread of 20 to 25 feet. Tall succulent stalks spring from a mat of roots, bearing tough, leathery leaves. In its flowering stage, the banana plant is quite fragrant, and the fruit that follows is a nutritional staple, rich in potassium. After fruiting, the stalk dies back and new stalks sprout from the mat to begin the cycle again.