GENERAL DESCRIPTION. 
of the stem extending on or nnder the ground, 
very far indeed in some ferns, farthest in the 
Common Bracken. When not under ground, these 
creeping stems are generally clothed with hairs or 
scales, sometimes becoming quite shaggy. The rhi¬ 
zome varies considerably in size, from that of the 
Common Polypody, which is as thick as one’s little 
finger, to that of the Film Ferns, as fine as thread. 
The fronds consist of two parts,—the leafy portion, 
and the stipes, which is the part of the stalk above 
the caudex or rhizome. The farther continuation of 
the stalk, forming in the leafy part a midrib, or mid¬ 
vein, which becomes branched when the frond is 
divided (as in the Oak Fern), is called the rachis 
(rachides in the plural). The stipes is generally 
more or less furnished with brownish membranous 
scales, sometimes only a few at the base, sometimes 
extending along the rachis. When the frond is 
divided quite down to the rachis, or midrib, it is 
said to be pinnate, and each of the leaf-like divi¬ 
sions is called a pinna (latin for a feather). When 
these pinna are again divided in the same manner 
the frond becomes bi-pinnate, or if thrice divided 
tri-pinnate. When the division is nearly but not quite 
down to the rib or midrib the pinnule (or small pinna), 
the pinna, or the frond, is called pinnatifid. 
The True Ferns are developed in a peculiar man¬ 
ner, coming up in a crozier-like form, having the 
rachis rolled in from the point to the base. In the 
more compound ferns the frond-divisions are each 
again rolled in after the same fashion. This is called 
