CLASSIFICATION OF FERNS. 
99 
4. P. Robertianum. Fronds ternate, mealy. 
5. P. alpestre . Fronds bipinnate; lance-shaped. 
aspidiu^:. 
3. Woodsia. 
1. W. hyperborea. Pinnae lobed. 
2. W. Ilvensis. Pinnae oblong. 
4. Aspidium. 
1. A. Lonchitis . Fronds pinnate. 
a . var. confertum. Frond smaller ; pinnae crowded. 
var. multifidum . Frond forked at the point, 
c. var. proliferum. Fronds bearing bulbs in the 
axils of the lower pinnae. 
2. -4. aculeatum . Frond bipinnate ; pinnules acutely 
wedge-shaped at the base. 
a . var. lobatum . Fronds rigid; narrow. 
A var. lobatum- acutum . Pinnules attenuated. 
c. var. crassum . Pinnules short; thick; over- 
lapping. 
d . var. multifidum . Fronds crested at the point. 
e. var. micaceum. Dwarf frond and large pinnae. 
/. var. acrocladia. Large; erect; crested. 
var. furcatum. Forked at the points and nar- 
rowed. 
h. var. interruptum. The pinnae narrowing to the 
base. 
3. A . angulare. Fronds bipinnate; pinnules obtusely 
angled at the base; stalked. 
a . var. subtripinnatum. Leaflets much indented. 
5. Nephrodium. 
1. N. Thelypteris . Fronds pinnate ; of delicate texture; 
sori near the margin. 
h 2 
