Red Mangrove (Rhizophora mangle)
The Red Mangrove is the most salt tolerant of the Mangroves.
The Red Mangrove has very shiny, glossy and pointy green leaves which are green on both sides of the leaf.
The Red Mangrove is easily recognized by numerous reddish, arching aerial roots called prop (or stilt) roots, which provide an important protective nursery habitat for many marine species.
Red Mangroves have small yellowish flowers with four petals and are pollinated by wind.
The Red Mangrove reproduces by long dangling propagules * (embryonic plants) 6 to 8 inches long which fall from the branches into the water or soft earth.
Black Mangrove (Avicennia germinans)
The Black Mangrove is characterized by its opposite leaves which are narrow and elliptical in shape; often found encrusted with salt. They are able to take up saltwater, use the water, and put the salt out onto their leaves.
The Black Mangrove has pointy, green leaves and is a little less shiny (than the Red Mangrove) and the leaf has a grey, silvery back.
The Black Mangrove has a single trunk with almost black bark.
Another way the Black Mangrove has adapted to its environment is by having roots that poke up out of the sediment instead of growing into it. These roots are called pneumatophores, which means “air breathing roots”. All plants need to breathe, so the Black Mangrove has developed these roots that act like snorkels, allowing the tree to get air, even though it is standing in seawater or soggy mud.
Black Mangroves have white flowers in spring and summer.
Black Mangroves reproduce by propagules * (embryonic plants) approx. 3/4 of an inch long.
White Mangrove (Laguncularia racemosa)
White Mangroves are found more inland in tidal areas, ponds and distinguished from the other mangroves as having no aerial roots.
Characterized by rounded leaves at the base and tip. The leaf is often notched at its apex (tip). Two glands at the base of each leaf act as perspiration glands removing excess salt and sugar to attract helpful insects. The leaves have microscopic pores which excrete salt.
White mangroves produce greenish-white flowers in spikes, blooming from spring to early summer.
White Mangroves reproduce by small propagules * (embryonic plants) approx. 0.2 inches long.
* A propagule is not a seed, but actually a tiny tree. Propagules develop from flowers. They mature on the tree and fall off in September. Once a propagule falls into the water, it floats, and can remain viable for up to a year.
Mangroves have a unique reproductive strategy for a plant. Like mammals they are viviparous, bringing forth live young. Instead of dormant seeds, they produce propagules that have embryonic development while still attached to the tree and only release at the appropriate time into water. Once released from the tree they require various dispersal times or an “obligate dispersal periods” (5–40 days depending upon the species) where the embryonic development continues. Once a favorable site is found there is a “obligate stranding period” before a tree emerges and begins to grow.
Mangroves as Land Stabilizers
Mangroves in Florida develop in the fine-textured sands and muds of lower-energy shorelines, and create a peat layer with a combination of leaf litter and accumulation of debris within the roots. All three mangrove species can hold sediments, and stabilize shorelines, reducing flooding and wind damage landward of the mangrove fringe.