GENERA AND SPECIES. 
PLATE III. 
POLYPODIUM. Linnzus. 
GEN. CHAR.—Fruit-dots naked, round, on the back of the frond 
at the ends of the veinlets, arranged in one or two rows on each side 
of the mid-rib; stipes articulated with the creeping, scaly root-stock. 
This is a very extensive genus, and is widely distributed 
over the entire globe. It is the typical genus of the tribe 
Polypodiez, and it is easily recognized by its having the 
fruit-dots naked, or without any covering (indusium). These 
are arranged on the back of the frond, and, in our species, 
are very regular and near the margin of the pinnules. 
Examined with a pocket lens before the disruption of the 
elastic ring, they have the appearance of globular masses of 
little berries. The veins are also very characteristic in this 
genus, branching from the mid-rib, twice or thrice forked, 
and always ending in little club-shaped points. Held 
between the observer and the light, especially after being 
decolorized, this peculiarity will be readily distinguished. 
Another characteristic of the genus is the articulation of 
the stipe or stalk with the root-stock. On examining an 
old plant, with a pretty thick rhizome, it will be found to 
be covered with rough knots, the old stalks, at their point 
of attachment, having left a series of scars, just as the leaf- 
stalks of some trees when they fall in autumn. 
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