The red mangrove (Rhizophora mangle), the colonizing mangrove, is the largest of the mangroves and is usually the first tree found when coming ashore. The red mangrove has prop roots often characterized as "walking" roots due to their resemblance to a person's legs while walking. The black mangrove (Avicennia germinanas), is found upland of the red mangrove. This tree has pneumataphores, aerial roots which resemble limbs growing upwards, that assist the tree in obtaining oxygen in its anaerobic substrate. The white mangrove (Laguncularia racemosa), grows further inland and is not continuously inundated with salt water. It does feel the effects of the salty environment though, and has two pores at the base of its leaves that excrete the excess salt. (photo: Florida Keys NMS)