26 PERNS OF GREAT BRITAIN. 



of Lastrea, or it is sometimes termed Gpmnocdrpium 

 Phegdpteris. 



3. P. Dryopteris (Oak Fern). — Fronds with three 

 branches, the divisions pinnate, the pinnae cut into 

 segments nearly to the midrib, blunt, the uppermost 

 entire ; dusters of capsules nearly marginal. This very 

 elegant species is sometimes called, also. Pale Mountain 

 Polj^ody, or it is known by the very characteristic name 

 of Tender Three-branched Polypody. The triple fronds 

 are a marked character of the plant, and it is slender in 

 form, thin, smooth, and fragile in texture. The height 

 of the frond is from four to six inches, and its colour is 

 of a brighter green than that of almost any other British 

 fern, though it loses this brightness if placed in a spot 

 exposed to the sun. Its mode of unfolding the young 

 fronds is very remarkable. In March and April these 

 emerge from the soil, exactly resembling, as Mr. Newman 

 has said, three little balls on wires. These folded scrolls 

 daily uncoil to the air and shaded light, tiQ, by the end 

 of June, not only are the three graceful branches de- 

 veloped, but the dark-brown masses of seed-cases are 

 crowding upon their under surfaces. Like many another 

 plant, however, which rapidly attains perfection, it is 

 somewhat short-lived, not surviving the earliest frosts. 

 The stalk is very slender, about twice the length of the 

 leafy part of the frond, of dark purphsh colour, very 

 brittle, vrith a few scales at its base. The three branches 

 of the frond are triangular, e^ach having a short stalk, 

 and the three uniting in an angular manner with the 

 common stalk of the frond. They spread loosely, and 

 are moved by the shghtest wind, the middle branch 



