Native Lagoon Shoreline Plants
Red Mangrove (Rhizophora mangle)
The red mangrove can grow to heights of up to 30 feet. It is the most recognizable mangrove in Florida because of its easily identifiable prop-roots. These roots extend downward in an umbrella shape from the trunk of the tree as well as from the branches. These roots not only anchor the plant in the mud it grows in, but also allows oxygen to enter the root and flow to the submerged portions of the root where the oxygen is needed. Red mangroves survive in salt water by blocking the salt from entering their roots when taking in water. They can do this at a 90-97% efficiency and only very occasionally need a dose of fresh water from rain or storms. The salt that is absorbed by the roots is stored in old leaves before they drop, which can be identified by the occassional bright yellow leaves on the tree. This ability allows the red mangrove to grow closest to the water's edge, even sometimes in the water, compared to the other two species of mangroves in Florida. Mangrove root habitat is essential nursery habitat for an estimated 75% of game fish and 90% of commercial species in south Florida. Their seeds, which are actually not seeds at all but miniature plants called propagules, are also the easiest to find. They are green, pencil-shaped and have a brown tip. In Florida, red mangroves can be found from Cedar Key (80 miles north of Tampa) south to the Keys and on the Atlantic Coast, from Volusia County (Daytona Beach) south to the Keys.
Black Mangrove (Avicennia germinans)
The black mangrove can grow to 50 feet tall. It is also easily recognizable by the hundreds of pencil-like root tips, or pneumatophores, that can be seen growing several inches out of the soil surrounding the trunk of the tree. These aerial roots serve the same purpose as the red mangrove's prop-roots, allowing the tree to get oxygen in low-oxygen conditions. The black mangrove is usually found farther upland, behind the red mangrove, where it is only exposed to the salt water at high tides. The black mangrove employs a different strategy to tolerate the high salinities where it grows. The salt absorbed by the roots is excreted out of pores in the leaf onto the leaf surface. Salt crystals can be found on the black mangrove leaves. The propagules are green and look like large, pointed lima beans. The black mangroves can be found farther north in Florida than the other two species, due to its ability to grow from roots after freeze damage. On the Gulf Coast they can be found as far north as Cedar Key, though they are small and shrub-like. On the Atlantic Coast, they can be found as far north as St. Augustine.
White Mangrove (Laguncularia racemosa)
The white mangrove grows to a maximum height of 40 to 60 feet. Unlike the red or black mangroves, it does not have any form of aerial roots. The leaves are easily distinguished from the other two species by their rounded tips and two small salt glands. In a strategy similar to the black mangrove's, these salt glands excrete the salt taken up by the roots onto the leaf surface. It is the least salt tolerant of the three species and is thus usually found farthest from the water's edge, behind the red and black mangroves. Its propagules are the smallest of the three, light green to gray in color, and shield-shaped. In Florida, white mangroves have the same distribution as red mangroves. These mangroves are limited to these geographic boundaries due to cold temperatures experienced during the winter months. All species of mangroves are tropical and sub-tropical plants.
Buttonwood (Conocarpus erectus)
Buttonwood trees are very similar to mangroves, but most scientists do not consider them an actual mangrove. They can grow to 40 feet and are also salt tolerant as are the three species of mangroves. Buttonwoods also have two salt glands to give it its salt tolerance, a feature similar to its close relative, the white mangrove. However, they are usually found farthest upland, behind the white mangrove, where they are only inundated with saltwater during violent hurricanes, if ever.
Buttonwoods are frost-sensitive and are limited to South Florida, similar to the red and white mangroves.
There is also a variation of the buttonwood, known as the silver buttonwood, Conocarpus erectus var. sericeus
. It is so named because the leaf is light gray and fuzzy in texture, giving it an almost silver appearance. The silver buttonwood has also been used as a hedge plant because of its attractive leaves and bark.
Sea Grape (Coccoloba uvifera)
Sea grapes are one of the most easily identified plants in Florida. They have very large, broad, round leaves that can measure up to 6-8 inches in diameter. Though often seen as small shrubs, they can also grow as trees up to 30 feet in height. The sea grape is also a salt-tolerant plant and is often found on the back dunes, coastal dunes, and other habitats very close to the ocean and Indian River Lagoon. It is a native of Florida, being found naturally from Pinellas County (St. Petersburg/Tampa Bay) on the Gulf Coast and Volusia County on the Atlantic down to the Keys. Their fruits resemble bunches of bright red grapes when ripe and can be found hanging from the base of the leaves, earning this plant its name. The grapes are edible and can be made into jelly or wine as well. Sea grapes are one of the most common landscaping plants, being found in many hedges and along roads throughout South and Central Florida. As well as an ornamental plant, they are a popular choice for oceanfront residents as a windbreak.
Sea-Oxeye Daisy (Borrichia frutescens)
Sea-oxeye daisies, also known as bushy seaside tansy, are another species of salt-tolerant plant that MRC commonly plants. It is naturally found in coastal marshes and back dunes and is oftentimes found in mangrove wetlands as well. Its name is derived from its bright yellow flower that closely resembles that of a daisy. Unlike other plants described above, sea-oxeye daisies are not restricted to Florida in the U.S. They can be found naturally as far north as Virginia and Maryland and as far west as Texas and Mexico. They can grow to almost 3 feet in height and can sprout many new shoots off of an interconnected system of roots called rhizomes. The leaves are a light green color but are covered with fuzz that makes the leaf appear to have a gray tint in some individuals. The flowers and seeds are a valuable food source for many species of birds, small mammals, and butterflies.