Mangrove Trees are the original Florida Keys Native

Have you ever seen a mangrove tree? If you’ve been to the Florida Keys, you surely have. They line the Overseas Highway all the way from Key Largo to Key West . They’re those green trees with the funky arched roots down at the water’s edge. They also make up all those islands that you see on both sides of the Overseas Highway. Some of them are made up of only one tree. They live in saltwater.

We have three species of these trees here in the Florida Keys. And they showed up here long before man did. They really prefer to be in the true tropics which have a constant temperature that is warmer than in the Keys. They’re very sensitive to temperature fluctuations and don’t grow well in sub freezing temperatures. The Florida Keys are in the subtropical zone, we get a bit cold in the winter, this causes them to grow smaller and thicker here.

The red mangrove is the most predominate in the Florida Keys. They usually grow to 25 or 30 feet tall here. They’re the ones with the arched red roots. Ariel roots also drop to the ocean bottom from their branches and take hold of the bedrock. These roots are their anchors. It allows them to grow in places other plants can’t grow and it keeps them in place when a tropical storm or hurricane blows thru the Florida Keys. They flower in the summer time. The flower is yellow. They produce seeds all year long. The seed is cigar shaped and tapered at both ends. The seed has the ability to sprout roots while still on the parent tree. When the seeds fall some of them stick up in the soft bottom around the mangrove cluster. Other seeds drift in the current with the tides until it gets lodged in a suitable place to grow. Here it begins a whole new mangrove island. Their leaves are succulent. They store saltwater in them. This gives them time to process it into fresh water through the process of osmosis. They actually pressurize the salt water to get the fresh water out. They can also store fresh water in their leaves. The salt from the osmosis process is expelled through the arched roots of the plant. The roots need to be out of the salt water each day to enable this to take place. This happens at low tide.

red mangrove seedling The black mangrove grows in waters that are more shallow than where the reds grow. They usually grow to a height of 20 to 25 feet. Their roots stick up vertically from the sand all around the tree. They look like a bunch of pencils sticking out of the ground. These roots help them to stay anchored. They also get freshwater from salt water through osmosis. The excess salt is expelled thru the roots at low tide. They produce a yellow flower. The seed is lima bean shaped. It too has the ability to sprout roots while still on the parent tree. They drop their seeds in the late summer and fall. Some stick up in the silt and others drift until they get caught up and grow a new tree there.

The white mangrove is more difficult to spot. It grows above the high water mark on dry land. They grow along side the buttonwood tree. The white looks more line a shrub. Their leaves are elongated and yellow green in color. The leaf has two small holes near the base of the stem on the under side of the leaf. These holes are for expelling the excess salt left over from the osmosis process. White’s are the smallest of the mangroves. It grows only to a height of 15 feet. They flower in mid summer. About a month later they have seeds, they look like a pea.

Mangroves need only a few inches of land on which to grow. As the roots get thicker they begin to trap sand , sediment, rocks and shells. This builds up thick layers of land and becomes elevated from the surrounding sea bottom. This process allows one mangrove to grow into an island and it allows for existing islands to grow larger.

They were once thought to be useless islands. Today we understand the importance to the ecosystem. They drop leaves and branches into the water. These decay and deliver essential nutrients that support the marine life making up the low end of the food chain. Many worms, clams, snails and crabs depend totally on decomposing mangrove leaves and branches for their entire diet.

small red mangrove tree

Many reef fish depend on the root system as a protective nursery. Most all fish you’ll catch in the Florida Keys have spent some part of their life in or near this habitat.

They also provide a protected breeding and nursery area for our water birds. Cormorants, white and blue herons, night herons, egrets, pelicans, roseate spoonbills, and frigate all raise their young in this tangle of roots and branches.

The maze of roots protects the shoreline from erosion caused by wind and waves.

Moosejaw
You may notice a rotten egg smell near these communities. What you’re smelling is sulfur. It’s usually noticeable when the tide goes out. This gives the built up land a chance to dry out and emit this odor.

In the past man has used mangroves for many purposes. Fruits from the red mangrove are edible. Leaves have been used to make tea, as a medicine and feed for livestock. Wood from the red mangrove is strong and water resistant. It’s been used to make boats, furniture, pilings, and houses. The black’s flower produces nectar. Bee keepers like to place their hives near these to produce a great tasting honey. The bark was used for tannin and dyes. Charcoal was made from the dense wood of the black mangrove and the buttonwood. They’ve also been used as a safe place to tie up a boat during a hurricane or storm. The only enemy to these trees other than hurricanes and tropical storms is man. Coastal development has been responsible for many acres of these trees disappearing. In 1985 the Mangrove Protection Act made it illegal to destroy or damage them in the State of Florida. They’ve been designated a species of special concern. You need a permit just to trim them back.

In the winter time in the Florida Keys I like to take the boat out and anchor on the lee side of a mangrove island. I enjoy listening to all the different sounds all those birds nesting inside the maze are making.

They are complex and interesting islands. The great thing is that the leaves stay on the tree and they stay green all year long. I really enjoy that.



Return From Mangrove Trees to Boating

Return From Mangrove Trees to N The Florida Keys