286 
BORDER SPECIES. 
At maturity the pinnules partly unroll and become more 
or less flattened. Specimens intergrading between fer- 
ROCK BRAKE, 
Cryptogramma 
acrostichoides. 
tile and sterile fronds are sometifes found. 
There are but two species of Cryfto- 
gramma in the world. The second species 
inhabits the northern and elevated portions 
of the Eastern Hemisphere. The two are very 
much alike and our species was formerly con- 
sidered a variety of the other. A few botanists 
now incline to add the slender cliff brake to 
this genus, which shows among other 
things, that the lines dividing certain 
} genera are very slight indeed. The 
generic name is in allusion to the way 
in which the plant fruits. From the 
appearance of the sterile fronds it is 
frequently called the parsley fern. 
Notholena dealbata. 
Our single representative of the genus 
Notholena extends no further east than 
Missouri and Kansas where it grows in 
the clefts of calcareous rocks. South- 
ward it extends to Texas and Arizona. 
Beyond its range, westward, there are up- 
wards of adozen species and of the thirty 
or more that compose the genus, a large 
majority are American. In the south- 
western part of its range our plant meets 
another species, VV. zzvea, of which it was 
once considered to be a variety. 
The fronds seldom reach a length of six inches and 
