fern is fairly common in alluvial soil over the United States and Canada.

[Illustration: Sori and sporangia of Ostrich Fern]



II

THE FLOWERING FERN FAMILY

_OSMUNDÀCEAE_

This family is represented in North America by three species, all of which
belong to the single genus.

OSMÚNDA

The _osmundas_ are tall swamp ferns growing in large crowns from strong,
thickened rootstocks; the fruiting portion of the fertile frond much
contracted and quite unlike the sterile. Sporangia large, globular,
short-stalked, borne on the margin of the divisions and opening into two
valves by a longitudinal slit. Ring obscure. (From Osmunder, a name of the
god Thor.)

(1) FLOWERING FERN, ROYAL FERN

_Osmúnda regàlis. Osmunda regàlis_, var. SPECTÁBILIS

Fronds pale green, one to six feet high; sterile part bipinnate, each pinna
having numerous pairs of lance-oblong, serrulate pinnules alternate along