254 THE SENSITIVE AINU OSTRICH FERNS. 



while it forms a more or less continuous border to all our 

 streams and ponds. Very few of those who pass it or 

 wade through it have any idea that it is a fern, for its 

 broad coarse fronds are far from the common conception 

 of fern leaves. 



The rootstock is as thick as a pencil and creeps just at 

 the surface of the earth, frequently branching. In addi- 

 tion to the fronds, it produces, here and there, append- 

 ages exactly like the bases of the stipes but which end in 

 a point and never become more than two or three inches 

 long. The fronds are produced all summer but the 

 young crosiers are most noticeable early in the year when 

 they push up in such numbers in all low grounds as to 

 make their tawny pink hue the prevailing one for some 

 days. Seen in the mass, the young fronds can scarcely be 

 called beautiful, but a single one taken just as the pin- 

 nules are unrolling and viewed from base to apex in the 

 plane of the blade will show such a succession of scrolls 

 and arches as to suggest a miniature of the interior 

 of some old cathedral. 



When the sterile fronds are fully spread they are, to 

 most eyes, coarse and ugly. They are ovate in outline, 

 pinnate below and pinnatifid toward the apex. The 

 pinnules are linear-lanceolate, the upper nearly entire, 

 the lower sinuate-toothed or lobed. The fronds are 

 borne on long stipes and often reach a height of more 

 than two feet. About midsummer the fertile fronds ap- 

 pear. They are shorter than the sterile, bipinnate, and the 

 pinnules resemble rows of little green berries strung along 

 the midribs. Many suppose each berry to be a sort of 

 sporecase like those of the rattlesnake fern, but it is 

 easy to see that they are simply closely rolled pinnules 

 enclosing the sori. Each sorus has an indusium but it 



