130 
BRITISH FERNS. 
11. Aspidium aculeatum, L. (Polystichum). 
Common Prickly Shield-fern. 
Caudex short, knotted, scaly, upright. Fronds 1 to 3 feet, 
lanceolate, bipinnate, tough. Pinnae pointed, alternate. Leaf- 
lets close, ovate, spiny. ISori in two rows near mid-vein. 
The name aculeatum refers to the sharp teeth on the 
margin of the leaflets . 
The root of this fern is long and spreading, and pene- 
trates so deeply into the earth, entwining with the roots 
of the brushwood amongst which it delights to grow, that 
it is very difficult to transplant it. The caudex is large 
and woody, densely covered with large rust-coloured 
scales ; the stems are thick and short, very scaly, as also 
when they traverse the leafy part of the frond, the very 
pinnae have scales on their stems. The fronds are lan- 
ceolate in form, broad in the shoulder in the best-grown 
plants, 2 feet in height and upwards, erect or slightly 
bending ; the pinnae are alternate, of harsh texture, their 
upper surface dark, their under a paler green, very glossy 
and close together. Both in aculeatum and lobatum the 
fructification is only upon the upper part of the frond. 
There is a narrow attenuated variety called by Mr. 
Lowe Polystichum aculeatum , var. lobatum acutum y one 
with very short leaflets of thick texture, and so closely 
placed as to overlap one another, var. crassum y both of 
which are rare. 
Aspidium aculeatum , var. multifidum , was found in 
Suffolk by Mr. Wollaston, and in Somerset by Mr. El 
worthy ; its peculiarity is that the apex of the frond is 
crested like Filix-mas cristata and Filix-fcemina cristata . 
The variety micaceum , of Barnstaple, is called from the 
kind of rock on which it grew. It is a dwarf form, both 
