i6 2 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. In its application to this species, it is 

 particularly appropriate, since it may be taken to refer 

 to the 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 pinnae 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 incisum and serratum. Fronds with pinnatifid 

 pinnae and serrate pinnules have also been reported. 

 This species, like the maidenhair spleenwort, is some- 

 times sweet scented in drying. The odour seems 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 is a 

 much older name and if we should go back to this, our 

 plant would be known as A splenium platy neuron. 



The Wall Rue. 



The wall rue (Asplenium ruta-muraria) is usually 

 found in limestone regions. It loves the sheltered 



