48 
it is our only species in the tribe -with articulate stipes. Among tlie 
DavalUece, the constantly epiphytic genera are llumata and DavaUla; 
Arthropteris and Oleandra are biologically epiphytes, though the former 
is probably terrestrial in origin, and one Oleandra maintains its ground- 
connection. N epliroJcpis is likewise epiphytic in fact^ or in its exposure 
and independence of ground water. Except Nephrolepis the pinnae of 
which are articulate, these all have articulate stipes. The terrestrial 
genera are Microlepia, Odontosoria and Dcnnslaedlia; they are without 
articulate stipes witli the exception of the single epiphytic species, Mi- 
crolepia Mrsuta. This argument is equally valid, whether M, hirsuta, 
M. Spelnncw and If. pinnaia are regarded as congeneric or in three 
related genera. Lindsaija is not specialized as an epiphytic genus; three 
San "Ramon t^pecies are terrestrial; L, McrrilU^ and very likely its near 
relatives; L. liymenop)liylloides and L. Ilavicei are ecologically like the 
Ilymenophyllacecb; L. pulcliella, L. hymenophylloides and L. Ilavicei grow 
in a habitat where even Polypodium is not usually articulate; and L. 
scandens grows in the very moist rain forest. 
Among our AspleniecB a single genus exists which when mature is 
always epiph^-tic in exposure; namely, Stenochla^na, Its pinnge under 
these circumstances are articulate, but young plants, near the ground 
and growing from it, are without articulations. Asplemum 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 Neoitiopteris group; others, such as the A. caudatum 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, S. 
schizocarpum. 
Our Picridew include no epiphytes and no plants with structural artic- 
ulations. However^ there arc species of Adianfum, notably A, opacum 
of Palawan, the pinnules of which are deciduous in an emergency. The 
Vitiar'iem as a group are nonarticulate epiphytes. To endure this con- 
dition .they liave thick, rolling leaves with very heavy epidermal walls 
and very few stomata. Loxogmmme is ecologically like them. 
The Pohjpodiece, with the exception, perhaps, of Tacniiis, 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 Dry nana group, 
the hunms-collecting habit of which demands permanent fronds, but 
which still fit their dry environment by being able to shed their pinnge 
or segments. Dryostacliynm shows advances to\vard 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- 
vrise identical Luzon fern has not even an apparent joint. Again in 
\ 
:*ti-^. ..-.^, 
* 
