GENERA AND SPECIES. 67 
Prater. X EX; 
ASPLENIUM RUTA-MURARIA. Linneus. 
WALL-RUE SPLEENWORT. 
This species, named from its resemblance to the common 
garden Rue, is the smallest of the Aspleniums in this coun- 
try, the average size being scarcely three inches in height. 
In sheltered locations it sometimes approaches five inches. 
It is generally found on exposed limestone rocks, selecting 
for its habitat the smallest holes and chinks to be found. 
It is much more difficult to get it out of its hiding place 
than any fern yet described. It is very hardy, remaining 
green all winter, even in exposed situations. It is very 
rare in Kentucky. Dr. Short found it on the cliffs of 
Kentucky River. I have found it at Rock Springs, Old- 
ham County. 
This little fern is not a very attractive-looking plant, and 
is very apt to be ignored by ordinary fern-gatherers. . In | 
Europe it is widely distributed, generally growing on old 
bridges, or on the ruins of old abbeys and castles. 
The fronds are bi-pinnate; the pinne wedge-shaped, 
often toothed at the apex. In the fully-developed plant 
the fruit-dots are so close together that they generally form 
an elongated brown patch. 
