• Florida's waters contain native species, like mangroves, and potentially harmful invasives.Alexa Miller/Photodisc/Getty Images
  
  Florida has some of the most distinctive ecosystems in the United States, and its subtropical climate and waters promote the growth of plant species found nowhere else in the country. Likewise, its saltwater environments, found in the Atlantic Ocean, the Gulf of Mexico and areas like the Everglades, allow for diversity in its saltwater plant species.
  
  

Mangroves

• Mangroves grow at the verge of two worlds in Florida--the land and the sea--and serve a vital role for each. Small trees with a vast, twisted network of roots, they grow on the coast and connect freshwater marshes to the salty sea, are able to withstand high salt levels and their periodic submersion by high tides. Their roots help hold soil in place, preventing erosion, especially during storms or when waves are high. They provide food and shelter for birds and marine organisms, serving such an important role that Florida law protects them from destruction. Although there are more than 50 species of mangroves found worldwide, only three species inhabit the Florida coasts, according to the Florida Department of Environmental Protection: the red, black and white mangroves.
  
  

Saw-grass

• Saw-grass (Cladium jamaicense) also grows along the coasts in Florida, choosing the brackish water between fresh and saltwater ecosystems as its preferred habitat. Although a Florida native-- it dominates the Everglades--you can also find saw-grass along the coast, ranging from Virginia, around the Florida panhandle and into Texas. Despite the name, saw-grass is actually a sedge, because it possesses triangular-shaped stems. Saw-grass spreads underwater via stems called rhizomes, allowing it to form dense mats that the University of Florida describes as "rivers of grass." Although a nuisance to boaters trying to navigate Florida's waterways, saw-grass forms an important source of food and shelter for Florida wildlife.
  
  

Hydrilla

• Ducking under the water, even more plants grow rooted to the bottom of Florida's marine waters, with their leaves completely submerged. Hydrilla (Hydrilla verticillata) can grow in fresh or salt water and forms stems up to 25 feet long, sometimes reaching the surface, where they form weedy-looking mats on top of the water. A fringe of elongated leaves grows along the stems, and small white flowers form at the water's surface. Hydrilla's ability to withstand a variety of challenging conditions--from varying salinity levels to low light to cold temperatures--coupled with its ability to reproduce quickly from leaf fragments and underwater tubers, make it an invasive plant in Florida, where it was most likely introduced as an aquarium plant that was released into the wild.