[Illustration: Fig. 2]

[Illustration: Fig. 3]

[Illustration: Fig. 4]

1. The Fern Family proper (_Polypodiàceæ_) has the spore cases stalked and
bound by a vertical, elastic ring (Fig. 1). The clusters of fruit-dots
containing the spore cases may be open and naked as in polypody (Fig. 2),
or covered by an indusium, as in the shield ferns (Fig. 3).

2. The Royal Fern Family (_Osmunda_) has the spore cases stalked with only
a rudimentary ring on one side, which opens longitudinally (Fig. 4).

3. The Climbing Fern Family (_Lygodium, Schizæa_) has the spore cases
sessile in rows; they are small, nut-like bodies with the elastic ring
around the upper portion (Fig. 5).[1]

[Footnote 1: These figures are enlarged.]

4. The Adder's Tongue Family (_Ophioglóssum, Botrýchium_) has simple spore
cases without a ring, and discharges its spores through a transverse slit
(Fig. 6).

5. The Filmy Fern Family (_Trichómanes_) has the spore cases along
a bristle-like receptacle and surrounded by an urn-shaped, slightly
two-lipped involucre; ring transverse and opening vertically (Fig. 7).

[Illustration: Fig. 5]