70 BRITISH PERNS. 



decayed vegetable matter, is much preferable to soil which is 

 much spent and comminuted, as indeed is the case with re- 

 spect to all Ferns. 



CHAPTEE XIJ. 



THE SCALE PERN. 



THE adopted botanical name of the Scale Fern is Ceterach Of 

 this genus there is only one British species, and this plant is 

 so different from all others as to be distinctly recognised at 

 a glance. The mark by which it is known is this : the back 

 of every frond is covered by densely-packed, brown, pointed, 

 chaffy scales. Among these scales, and concealed by them, 

 lie the elongate sori, which are anomalous, in regard to their 

 relationship, in having no indusium. The affinity of Ceterach 

 is without doubt with the A$plenium-\\kQ Ferns, this being 

 the case they ought to have an indusium. No indusium, 

 however, exists here, unless it be represented by a kind of 

 membranous ridge, which is to be found on the receptacles 

 just behind the sori, and is the part which has sometimes 

 been called an indusium. The probability is, that it does re- 

 present that organ, which is not largely developed in conse- 

 quence of the presence of so dense a covering of scales, these 

 not only serving the purpose of a cover to the sori, but per- 

 haps, from their crowded position, preventing the proper 

 formation of the usual form of cover. 



The name Ceterach is an alteration of the word Chetfierdk, 

 which was applied to this plant by Persian and Arabian 

 medical writers. 



COMMON SCALE-FERN, OK SCALY SPLEENWORT. [Plate VI. fig. 3.] 



This species has many names. That most to be preferred 

 is Ceterach officinarum, but it has also been called Asplenium 

 Ceterach, Scolopendrium Ceterach, Grammitis Ceterach, Noto- 

 lepeum Ceterach, and Gymnogramma Ceterach. 



It is a dwarf, evergreen, distinct-looking and very pretty 

 Fern, growing in tufts. The fronds when fresh are thick and 

 fleshy, and from this cause they are perfectly opaque when 

 dry. Their size varies, according to the circumstances of 

 their growth, from two to six inches in length, rarely exceed- 

 ing the latter. They grow on a short scaly stipes, and are 

 cither pinnatifid, as is commonly the case, or more rarely 

 pinnate, the difference being, that in the latter tJh frondfe 



