In epiphytic forms the rhizoids of the epiphyte often penetrate into the tissue of the host, and certain epiphytes are not known to occur excepting in connexion with a certain host; but to what extent, if any, there is a partial parasitism in these cases has not been ascertained.
As in the IndoMalayan sub-region, epiphytic orchids are probably most numerous in point of species, but the genera and even sub-tribes are far more restricted in their range than in the Old World; 4 sub-tribes with 74 genera of Vandeae are confined to South America, though varying in range of climate and altitude.
Among the plants the wild banana, pepper, orange and mangosteen, rhododendron, epiphytic orchids and the palm; among mammals the bats and rats; among birds the cassowary and rifle birds; and among reptiles the crocodile and tree snakes, characterize this element.
Ground orchids and tree orchids are well represented; Polystachya liberica, an epiphytic orchid with sprays of exquisite small flowers of purple and gold, might well be introduced into horticulture for its beauty.
A number of species of Lycopodium are epiphytic and those of Isoetes live submerged in water.
Euphaeophyceae are almost exclusively marine, growing on rocks and stones on the coast, or epiphytic upon other algae.
The Ferns exhibit a wide range in size from the minute epiphytic Hymenophyllaceae, with leaves barely a centimetre in length, to gigantic tree-ferns 80 ft.
Phlegmaria and other epiphytic forms the prothallus consists of fine branches growing saprophytically in rotting wood (fig.
Thus there are a few 3 Ferns which climb, others are .8 water plants, while many, especially those which live as epiphytes, are more or less xerophytic. Some of the epiphytic forms (Polypodium quercifolium, Platycerium) have strongly dimorphic leaves, the sterile leaves serving in some cases to catch falling debris, and thus to provide the plant with soil.
Peronospora, or to the young mycelia of epiphytic parasites, e.g.