You just can't miss the hanging draperies of this plant; it's as if the trees wear grizzled beards. The name is a misnomer, though. Spanish Moss is not a moss at all - it is a monocotyledonous flowering plant. A bromeliad, to be specific. It actually looks more like a lichen than a moss, as suggested by the specific epithet of its scientific name: usneoides. When you see a scientific name with the epithet appended with an "oides" ending, it means "resembles". So, in the case of Spanish Moss, usneoides means "resembles Usnea", and Usnea is a genus of beard lichens.
But the pendant growths of Spanish Moss are air plants, and derive their nutrients from rain and air, and perhaps minerals leached from the host plant. As might be expected from such an obvious plant, it has garnered a fair share of attention. Balladeer Gordon Lightfoot - of Edmund Fitzgerald fame - wrote a tune entitled "Spanish Moss". So did the punk band Against Me!, and you can hear their song Spanish Moss, HERE. As an interesting automotive footnote, Spanish Moss was used widely in the early 1900's to stuff the seats of automobiles.
Pelegrina tillandsiae, is said to only inhabit this plant, and bats, snakes, insects and who knows what all lurks in its tangled masses. The gorgeous songbird above, the Northern Parula, is strongly associated with Spanish Moss and this warbler typically makes its nest in the plant, at least where the two species overlap.
For me, one of the highlights of heading into the Deep South is the trees tangled in this interesting member of the Bromeliad family.