BRITISH FERNS. 
7 1 
THE POLYSTICHUMS (THE SHIELD FERNS). 
IN Great Britain we have three species of this genus, viz., 
P. lonchitis (the Holly Fern), P. aculeatum (the Hard Shield 
Fern), and P. angulare (the Soft Shield Fern), and it is a 
very curious fact that though there are numerous exotic 
species, the varietal forms of these are extremely few, while, 
especially in the two last-named, an immense number of 
distinct forms have been found wild, and even P. lonchitis, 
PoLYSTICHUM ANGULARE VAR. PLUMOSUM DENSUM. 
1. The Normal Form of Species. 2. Wild Find 
in South Devon. 3. Frond of Densum raised 
from 2. 4. Pinnae of Imbricatum raised from 
Bulbil of Densum. 
limited as it is in 
range, has afforded 
several. All three 
species are 
thoroughly ever- 
green, and the 
whole genus is 
peculiar in the fact 
that normally the 
pinnules are shaped 
something like a 
fingerless glove, the 
thumb sticking out 
at almost right angles 
to the other por- 
tion, and more or 
less acute points 
terminating the 
divisions. In the 
abnormal forms this 
feature usually per- 
sists, though the 
make of the pinnules 
is varied to the 
utmost. In the Holly 
Fern we have the 
simplest form, the 
frond consisting 
merely of two rows 
of undivided glove- 
shaped divisions, 
which in this case 
form pinnae. In the 
other species, which 
are usually of much 
larger growth, the 
