_.

[Illustration]

(3) Fruit-dots and indusium linear. (But see _Athyrium_.)

Very long, nearly at right angles to the midrib, double; blade thick
oblong-lanceolate, entire; heart-shaped at the base. Hart's Tongue.
_Scolopendrium_.

[Illustration]

Shorter and irregularly scattered on the under side of the frond, some
parallel to the midrib, others oblique to it, and often in pairs or joined
at the ends; blade tapering to a slender tip. Walking Fern. _Camptosorus_.

[Illustration]

Short, straight, mostly oblique to the midrib. Indusium rather narrow,
opening toward the midrib, fronds lobed or variously divided. Spleenworts.
_Asplenium_.

[Illustration]

Short, indusium usually more or less curved and frequently crossing a vein.
The large spleenworts including Lady Fern. _Athyrium_.

DESCRIPTIVE TEXT OF THE FERNS

In this manual our native ferns are grouped scientifically under five
distinct families. By far the largest of these groups, and the first to be
treated, is that of the _real ferns (Polypodiaceae)_ with sixty species and
several chief varieties. Then follow the _flowering ferns (Osmundaceae)_
with three species; the _curly grass_ and _climbing ferns (Schizaeaceae)_
with two species; the _adder's tongue_ and _grape ferns (Ophioglossaceae)_
with seven species; and the _filmy ferns (Hymenophyllaceae)_ with one
species.

Corresponding with these five families, the sporangia or spore cases of
ferns have five quite distinct forms on which the families are founded.

[Illustration: Fig. 1]

[Illustration: Fig. 2]

[Illustration: Fig. 3]

[Illustration: Fig. 4]

1. The Fern Family proper (_Polypodiaceae_) 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, Schizaea_) 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 (_Ophioglossum, Botrychium_) has simple spore
cases without a ring, and discharges its spores through a transverse slit
(Fig. 6).

5. The Filmy Fern Famil