Of the swallowworts, there are four species in three genera that occur in Florida. The two species in the genus Metastelma are only found in limited areas from Brevard County on the east coast and Collier County on the west coast, southward into the Keys. The other two species are Gulf Coast swallowwort (Pattalias palustre) and leafless swallowwort (Orthosia scoparia), both of which have narrow nearly linear leaves when present. Pattalias palustre nearly always has leaves and they do not have any apparent petioles, instead gradually narrowing towards the base which is about as wide as the stem. Orthosia scoparia has leaves with obvious petioles that are distinctly narrower than the stem when young and typically shaded by larger plants. As the vines grow out over the other vegetation and into the sun, the leaves drop off, so this vine is frequently seen living up to its common name.
