144 
Me 
e 
SPINULOSE 
SHIELD FERN. 
Aspidium spinulosum 
intermedium, 
THE WOOD FERNS. 
foliage. The blade is nearly three 
times pinnate, the ultimate pin- 
nules being small, oblong, blunt 
at the ends and spinulose 
toothed. The cutting, however, 
varies greatly. The secondary 
divisions are not always com- 
pletely pinnate but they are al- 
“ways so near it as to give a very 
delicate, lace-like effect to the 
frond. The pinnules on the in- 
ferior side of the pinnz are fre- 
quently elongated especially in 
the lowest pair, a characteristic very com- 
mon in this family. The sori are borne 
on the backs of ordinary fronds in what 
approximates a double row on each of 
the secondary divisions, a sorus being 
located at the base of each pinnule. It 
not infrequently happens, however, that 
the pinnules themselves bear one or more 
sori which breaks up the regularity of 
the rows and makes the arrangement of 
the fruit dots less definite than it is in 
other species. The indusium is kidney- 
shaped and smooth. The sporangia early 
turn to a shining black and do not be- 
come brown until late in the season. 
The fronds are produced from a short 
stout rootstock and all appear in early 
spring. 
The two varieties of this species are so much like it in 
appearance that good students cannot always agree as to 
