FEENS OP GREAT BEITAIN. 37 



distinct, and sometimes distant from each, other, obtusely 

 triangular, and lobed, and they are usually alternate 

 on each side of the rachis; those at the lower part 

 of the frond being generally farther from each other 

 than the higher leaflets. The upper surface is nearly 

 smooth, but a few minute hairs are scattered along 

 the margin and under-surface. The veining is not 

 a very marked feature of the species. There is no 

 distinct mid-vein, but small veins branch into each lobe, 

 not quite reaching the margin of the leaflet. At the 

 extremity of these veins are placed the clusters of cap- 

 sules, which soon form a crowded mass. The frond is 

 of a brownish green colour ; the roots black, wiry, and 

 branched; and the underground stem very large in 

 proportion to the frond. Many botanists consider that 

 this species and the last should be united, as they doubt 

 if there is any difference between them which is not 

 caused by variations of situation and circumstances of 

 growth. This fern is called also by various botanists 

 Acrostichum alpinum, Acrdstichum hyperboreum, JPolypo- 

 dium hyperhorewm, or Woodsia hyperhorea. 



5. Lastrea (Lastrea). 



1. L. Thelijpteris (Marsh Fern). — Fronds pinnate; 

 pinnce pinnatifld; clusters marginal, near together, at 

 length mingling into a mass. Several of the most con- 

 spicuous of our native ferns belong to the genus Las- 

 trea, some of them almost rivalling the Common Brake in 

 size. It was formerly comprised in the genus Aspidium, 

 and its chief distinction consists in the kidney-shaped 



