( 4i ) 
fern is, that the under skin of the pinnule is 
also extended beyond the sori, which are thus 
enclosed between the two. 
Venules. Free in barren fronds. In fertile fronds 
their apices joined by a marginal vein. 
GROUP I; GENUS XIII; SPECIES I. 
PTERIS AQUILIN A. (Common Brake, or Bracken.) 
Plate VI. 
Fronds. Triangular, bi- or tri-pinnate, or compound 
and much divided. Primary pinnae opposite, 
broad in outline; secondary pinnae narrower. 
Ultimate pinnules linear, tapering, and very 
deeply pinnatifid. The edges of lobes of 
fertile fronds reflexed. Rachis and stipes 
yellowish-green; the base of the latter dark 
purple, and about one-half the length of the 
entire frond. 
Growth. Erect and rigid. Fronds rising from a 
creeping, dark, velvety rhizoma. 
Height. Varies greatly ; from one foot to eight or nine 
feet. 
Colour. Light, faded green. 
Habitats. Woods, heaths, moors, hedgerows. The 
commonest of the British ferns. 
