118 
BRITISH FERNS. 
stem, which bends at its juncture with the branches ; 
the form is pentangular, each of the three branches form- 
ing an acute triangle, the bases of the lowest branches 
add two short sides to what would otherwise be a trian- 
gular frond. 
Each of the three branches is furnished with opposite 
rows of pinnee, or rather of pinnules, the side branches 
being themselves pinnae, and these again are beset by 
oval leaflets. The colour of the frond is of a very bright 
green, glossy, and delicate in texture. The sori are 
produced in abundance on the older fronds, while the 
younger ones attain a lower height, have more outspread 
leaflets and more angularly bent stems. 
Nothing can exceed the beauty of a flourishing colony 
of this oak-fern, growing, as we often see it, under a 
birch grove upon the bank of some Yorkshire streamlet, 
or in the heart of some shady Somersetshire combe. A 
myriad wiry stems, shading to every tint of purple and 
brown, rise from the branched caudex, which pushes its 
arms freely among moss and roots and half-decayed 
leaves, enjoying perpetual moisture. The stems spring- 
ing from the old branches of the caudex rise half a foot 
in height, bearing their leafy three-branched crown 
proudly, its verdant standard floating from the blunt- 
angularly bent stem, and clothed underneath with a 
rich harvest of brown sori. The young shoots of the 
caudex bear weaker stems, the leafy part of the frond 
lying almost horizontally, from the sharper inclination 
of the deflexion of the stem, thus making a kind of 
underwood of fronds, over which the fully-developed 
ones tower in conscious dignity. All the fronds are of 
a rich green colour, but the lighter shade of the young 
ones is like sunshine itself, and all the verdant ^>enta- 
