48 
it is our only species in the tribe with articulate stipes. Among the 
Davalliece', the constantly epiphytic genera are Humata and Davallia; 
Arthropteris and Oleandra are biologically epiphytes, though the former 
is probably terrestrial in origin, and one Oleandra maintains its ground- 
connection. Nephrolepis is likewise epiphytic in fact, or in its exposure 
and independence of ground water. Except N ephrolepis the pinnae of 
which are articulate, these all have articulate stipes. The terrestrial 
genera are M icrolepia, Odontosoria and Dennstaedtia ; they are without 
articulate stipes with the exception of the single epiphytic species, Mi- 
crolepia hirsuta. This argument is equally valid, whether M. hirsutar, 
M. Speluncce and M. pinnata are regarded as congeneric Or- in three 
related genera. Lindsaya is not specialized as an epiphytic genus; three 
San Ramon species are terrestrial; L. Merrilli, and very likely its near 
relatives; L. hymenophylloides ' and L. Havicei are ecologically like the 
Hymenophyllacece ; L. putdiella, L. hymenophylloides and L. Ildvicei grow 
in a habitat where even Polypodium is not usually articulate; and L. 
scandens grows in the very moist rain forest. 
Among our Aspleniece a single genus exists which when mature is 
always epiphytic in exposure; namely, Stenochlcena. Its pinnae under 
these circumstances are articulate, but young plants, near the ground 
and growing from it, are without articulations. Asplenium. can not be 
regarded as a specialized epiphytic genus as its many epiphytic species are 
altogether too diverse in their adaptations, indicating that they have 
assumed this habit separately; some are sclerophyllous xerophytes, as 
the Neoltiopteris group; others, such as the A. eaudatum group, seem 
to become dry without great injury, and a few, such as A. Belangeri 
are rain forest species, just as is our epiphytic Scolopendrium, 8. 
schizocarpum. 
Our Pteridcce include no epiphytes and no plants with structural artic- 
ulations. However, there are species of Adiantum , notably A. opacum 
of Palawan, the pinnules of which are deciduous in an emergency. The 
Vittariece as a group are nonarticulate epiphytes. To endure this con- 
dition they have thick, rolling leaves with very heavy epidermal walls 
and very few stomata. Loxogramme is, ecologically like them. 
The Polypodiea, with the exception, perhaps, of Taenitis, are a very 
natural tribe in which the axis of evolution has been in the air under 
standard epiphytic conditions. From this axis are many offshoots, of 
which one remote one may be Taenitis which is terrestrial and non- 
articulate. Again articulate stipes have been lost by the Drynciria group, 
the humus-collecting habit of which demands permanent fronds, but 
which still fit their dry environment by being able to shed their pinnaj 
or segments. Dryostacliyum shows advances toward the loss, of the 
articulation; D. splendens of Mindanao having a joint evident to the 
eye, but without function (that is, a vestigial structure), while the other- 
wise identical Luzon fern has not even an apparent joint. Again in 
