ies THE ROCK SPLEENWORTS, 
fronds do not survive the winter, but the sterile are ever- 
green. In this, as well as in the way the plant carries its 
two sorts of fronds, it strongly suggests the crested fern. 
Part of a fruiting frond is shown in the Key. 
The ebony fern derives its name from the dark rachids. 
It is said that the word ebony is from the Hebrew eben 
meaning a stone. Inits application to this species, it is 
particularly appropriate, since it may be taken to refer 
tothe colour of the rachis, or to the fern’s habit of grow- 
ing among the rocks. It is also called screw fern because 
the alternate fertile pinne are set upon the rachis in 
such a manner that they resemble the threads on a 
screw. While the plant is growing, the resemblance at 
a short distance is very striking. 
This species is found from Maine and southern Can- 
ada to the Tropics and westward to Colorado. It is not 
abundant except in rocky soil. It grows well in cultiva- 
tion and is said to occasionally root at the apex. 
The pinnules incline to vary in the depth of the serra- 
tures. Deeply incised forms have been described as the 
varieties ¢zcisum and serratum. Fronds with pinnatifid 
pinne and serrate pinnules have also been reported. 
This species, like the maidenhair spleenwort, is some 
times sweet-scented in drying. The odourseems to come 
from the roots or rootstock and often remains for some 
time in the dried plants. Until recently our fern has 
been called by the specific name of ebeneum. There isa 
much older name and if we should go back to this, our 
plant would be known as Asplentum platyneuron. 
The Wall Rue. 
The wall rue (Aspleniuim ruta-muraria) is usually 
found in limestone regions. It loves the sheltered 
