"Our
Ferns in Their Haunts," but substitutes other and larger specimens. Five of
these are from Waters' "Ferns" by permission of Henry Holt & Co.

As the indusium, which often determines the name of a fern, is apt in some
species to wither early, it is important to secure for study not only a
fertile frond, but one in as good condition as possible. For convenience
the ferns may be considered in two classes.

I

THOSE WHICH HAVE THE FRUITING PORTION IN GREENISH, BERRY-LIKE STRUCTURES
AND NOT ON THE BACK OF FRONDS

A. FRUITING FRONDS WHOLLY FERTILE

(Fertile and sterile fronds entirely unlike)

[Illustration]

1. Fruit in a one-sided spike in two ranks; plants very small; sterile
fronds thread-like and tortuous.

Curly Grass. _Schizaea_.

[Illustration]

2. Fruit in a club-shaped, brown or cinnamon-colored spike loaded with
sporangia; fruit in early spring.

Cinnamon Fern. _Osmunda cinnamomea_.

[Illustration]

3. Fruit in berry-like, greenish structures in a twice pinnate spike, which
comes up much later than the broad and coarse pinnatifid sterile fronds.

Wet ground. Sensitive Fern. _Onoclea_.

[Illustration]

4. Fruit in pod-like or necklace-like pinnae; fertile frond pinnate; sterile
frond tall, pinnatifid; fruit late.

Ostrich Fern. _Onoclea struthiopteris_.

B. FRUITING FRONDS PARTLY STERILE

[Illustration]

1. Fruiting portion in the middle of the frond; two to four pairs of
fertile pinnae.

Interrupted Fern. _Osmunda Claytoniana_.

[Illustration]

2. Fruiting portion at the apex of the frond. Sterile pinnae palmate; rachis
twining.

Climbing Fern. _Lygodium_.

[Illustration]

Sterile pinnae pinnate; fronds large, fertile portion green, turning brown,
forming a panicle at the top.

Royal Fern. _Osmunda regalis_.

[Illustration]

3. Fruiting portion seemingly on a separate stock a few inches above the
sterile.

Sterile part an entire, ovate, green leaf near the middle; fertile part a
spike.

Adder's Tongue. _Ophioglossum_.

[Illustration]

Sterile portion more or less divided; fruit in racemes or panicles, rarely
in spikes.

Grape Ferns. Moonwort. _Botrychium_.

II

THOSE WHICH HAVE THE FRUITING PORTION ON THE BACK OR MARGIN OF FRONDS

A. INDUSIUM WANTING

[Illustration]

1. Fruit-dots large, roundish; fronds evergreen. Rock species.

Polypody. _Polypodium_.

[Illustration]

2. Fruit-dots small, roundish; fronds triangular.

Beech Ferns. _P