BRITISH FERNS. 81 



still adds in some degree to their strength and durability. The 

 rhizoma is black, scaly, and tufted. The fronds make their 

 appearance in May and June, arrive at maturity in August and 

 September, and remain perfectly green throughout the winter ; 

 they are fertile only. 



The rachis is naked for a third part of its length, smooth, 

 shining, and black throughout ; the form of the frond is narrow, 

 linear, and simply pinnate : the pinnae are dark green, and very 

 numerous ; irregularly ovate, obtuse at the apex, and more or 

 less crenate at the margins ; they are usually distinct and distant, 

 but sometimes crowded, and each recumbent on the one preceding 

 it ; they are attached to the rachis by their stalks only, and when 

 the frond approaches decay the pinnae fall off like the leaves of 

 phaenogamous plants, leaving the rachis a bare denuded bristle : 

 in size they vary from that of those represented in the fronds, 

 to that of the detached pinnae illustrating the fructification. 



The lateral veins are forked soon after leaving the midvein, the 

 anterior branch bears an elongate linear mass of thecas, almost 

 immediately after the fork : this mass is at first covered with an 

 elongate, linear, white membranous indusium ; as the thecae 

 swell this becomes obliterated, and the masses, which are black, 

 become nearly confluent in two portions, which, however, very 

 rarely unite over the midrib : the masses are ten or twelve in 

 number. 



The gothic windows of an old abbey afford many convenient 

 crevices for this pretty fern ; but the ferns sketched in the Vignette 

 include the Hart's-tongue, and other species. 



