The following text is copied from the Miami-Dade government page. It is only reproduced here for educational purposes.
Mangroves are tropical trees that have adapted to salt water and wave activity. There are three species of mangroves in Florida. They are related by the way they have adapted to a mutual habitat, but are actually members of different plant families
The red mangrove (Rhizophora mangle) is most commonly recognized by its “prop” roots. They sometimes begin very high up on the trunk, arch out and then down into the soil. These roots provide tremendous support for the tree, which is necessary since it encounters rigorous waves, varying tides, and frequent storms. This root system also allows the mangrove to receive oxygen that is needed for growth that would otherwise not be available from water-saturated soil. Many marine organisms use this root system as a nursery ground, and these roots act as an anchor, protecting the shoreline from eroding
The black mangrove (Avicennia germinans) root system is opposite of the red mangrove. It extends down into the soil from the trunk and its ends come upward out of the ground, sometimes as much as a foot. These outcroppings are termed pneumatophores and their function is to exchange gas. This mangrove is found in the interior of the wetland, where tidal action is not as severe.
The white mangrove (Laguncularia racemosa) can occur almost anywhere in a wetland, but is mostly found in higher elevations, such as the inland edges. The root system can vary depending on the conditions of the wetland, and its distinguishing feature is the two glandular openings on the leaf stem.
Another species that can often be found in mangrove wetlands is the Green buttonwood (Conocarpus erecta). This species is a member of the white mangrove Family and also resides around the higher elevations of the mangrove wetland. This species is restricted to South Florida due to its frost intolerance.