PTERIS. 
169 
species is still more clearly exhibited when it attains its 
greatest luxuriance, for the full-grown fronds then consist 
merely of a series of pairs of branches from the bottom to 
the top. The unrolled young fronds are very curious 
objects, and the watching of their development will be 
found full of interest. 
The stipes is downy while young, and furnished with 
sharp angles, which, when mature, will wound the hand 
severely, if it be incautiously pulled. The part under- 
ground is black, like the creeping stem itself, and is 
spindle-shaped just at the base, where it permanently 
retains the downy or velvety surface which was present in 
the upper portions while young. Average specimens of 
the fronds are tripinnate, that is, they produce a certain 
number of pairs of branch-like pinnae, which branches are 
bipinnate. We must confine our further description to 
one of these branches, selected from the lower part of the 
frond, where they are more perfectly developed than in the 
upper parts, — such a branch, in fact, as is represented, in 
Plate XVII. The general form is ovate, a little elon- 
gated ; that of its pinnae (the secondary pinnae) narrow 
lanceolate. These latter are placed rather closely together, 
and are again divided into a series of pinnules, which are 
