73 
m 
accedens. Drt/moglossam and Niphoholus are unmistakably related, and 
^ i^Iaplwglossum is probably parallel in genesis to Niphoholus, with a 
reasonably near common ancestor. Elaphoglossum is no small genus 
in the Philippines. 
From the Craspcdaria group are descended the species of Phi/matodes 
with more ample, entire fronds, among wliich several natural groups 
are more easy to recognize than to define. From one of tliose, perhaps 
from some- such fern as P. tiiqiietnim, the Selliyuea grouji is dcHved. 
More than one of these groups with entire fronds lias descendants with 
the fronds deeply pinnatifid, as in P. plnjmaiodcs. One of the most 
natural of the latter groups with the fronds almost pinnate, is exceed ingly 
thin in texture, and inhabits water courses and very moist banks. 
Among its species are P. imigne and P. dolichoptennn. P. eUiptlcu/ii 
is an outgrowth of this group, and is, therefore, not intimately related 
to the other species called Selliguea, Another group of the pinnatifid 
species includes P. incurvatum and P, pahnalum. The former is dcT 
cidedly dimorphous, and strongly suggests the pro])al)]e ai^coslry of 
Christiopieris, Cheiropleuria, too, has possibly its source here, but I 
strongly suspect that both it and Taenitis are Aspidioid in origin. An- 
other group in Phyniatodes is Mijnnecophila {As pido podium), the com- 
monest species of winch is P. sinuosnm. This group lias given rise to 
Lecanopteris. 
Finally, the most diversified and highly specialized outgrowth of 
Phymatodes is the Dnjnaria groiip of genera. Within the usually ac- 
cepted limits of Phymatodes, P. mttsaefolium and P. {Drynariopsis) 
heradeum lead to this group, from the large group of species with 
ample, entire fronds. From some such plant as P. hcracJeuni, Drynnria 
has evolved by the restriction of the humus-collccting work to distinct 
fronds. From a similar ancestor, Aglaoviorpha and Dryosiachyum have 
been evolved by the restriction of the fertile region to the apex iA the 
frond and the fusion of the sori. From these, Thayrria, the most highly 
specialized of the group, has probably been derived. The Drytuiria 
group is a very natural one, characterized by its habit, by the fleshy 
rhizome, and its scales, by tlie frond form (o\ec])tion', D. rigidula) and 
venation, and by the remarkable cutting-off of the segments. PhoLinop- 
teris is a probable relative of Dryosiachyum, the affinity being indicated 
by the location of the fertile region, absence of definite sori, and the 
glands at the bases of tlie pinnte; young fronds of J), pilosum have rows 
of lime dots. 
The Phymatodes group, as a whole, is xerophytic and characterized 
by the presence of a specialized hypodermis beneath the u])per epidermis. 
The cells of this tissue are irregular in surface view, wry often more 
so than the epidermis; sometimes one, sometimes the other has the 
thicker walls. Under conditions that render the hypodermis unnecessary 
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