This is Casuarina glauca. Male and female flowers occur on different trees, and there are no female trees known in Florida. This plant reproduces entirely by fragmentation or by “suckering” which is sending new plants up from roots, as seen below.

A section of root was uncovered showing the new trees spouting from the root.

This species is Casuarina equisetifolia. It has male and female flowers on the same tree and it doesn’t exhibit suckering. Note “scraggly” look of tree compared to C. glauca to the left.

This is a hybrid between the two species above. It has both male and female flowers on each tree and shows some suckering.

View of non-native “junk” habitat, courtesy of Australian pine and Brazilian pepper. 

Despite claims to the contrary, Australian pines actually increase erosion by crowding out and replacing native plants with deeper roots. The shallow roots of Australian pine allow the land to erode from beneath them until they topple over.

In this close view notice how the shore has eroded from beneath the tree’s shallow roots.

This tree was toppled in a hurricane but it hasn’t died. Notice how absurdly shallow the root system is - no part of it penetrated deeper than about 20 centimeters (< 10 inches). These trees are worthless at holding soil.