34 BRITISH FERNS. 



this recurved margin of the frond ; but as they grow they 

 join laterally (in technical language, become confluent), form- 

 ing two lines of fructification lengthwise the segments of the 

 fronds. 



The name Allosorus is compounded from the Greek, and 

 comes from two words, which means various and a heap ; the 

 intention no doubt being to indicate the variation in the ar- 

 rangement of thcsori, occurring among the plants originally 

 thought to belong to this family. It may also apply to the 

 apparent difference of arrangement in the sori of this plant 

 at different stages of development, the young sori forming 

 distinct roundish patches, and the older becoming effused into 

 larger shapeless masses. 



ROCK BRAKES, OR MOUNTAIN PARSLEY. [Plate H. fig. 1.] 



The scientific name Allosorus crispus is that preferred by 

 us for this Fern. Others prefer to use one of the following 

 Cryptogramma crispa, Pteris crispa, Osmunda crispa, the first 

 of these three being however now mostly used, when Allo- 

 sorus is passed over. 



This elegant little plant, which has considerable first-sight 

 resemblance to a tuft of parsley, and is hence sometimes 

 called Mountain Parsley, grows in a dense tuft, throwing up 

 its fronds in May or June, and losing them in the course of 

 the autumn. The fronds average about six inches in height, 

 and are generally somewhat three-cornered in outline, with 

 a longish, slender, smooth stalk. They are, as already stated, 

 of two kinds ; both kinds being twice or thrice pivuate, ana 

 of a pale green colour. The segments into whicL the sterile 

 fronds are cut, are more or less wedge-shaped, and notched 

 or cleft at the end. The fertile fronds have the segments of 

 an oval or oblong or linear form. The divisions of the fer- 

 tile frond have a slightly tortuous midvein, producing simple 

 or forked venules, which extend nearly to the margin, each, 

 for the^most part ; bearing near its extremity a circular sorus. 

 There is no true indusium, but the sori are covered by the 

 reflexed and partially bleached margins, which sometimes 

 almost meet behind, so that the spore-cases are quite con- 

 cealed. The patches of spore-cases are at first distinct, but 

 ultimately they spread out and become more or less confused 

 and blended. 



The Rock Brakes is a mountain Fern, choosing to grow in 

 stony situations. It is comparatively rare and local ; most 

 abundant in the nortli of England and Wales, and less plen- 

 tiful in Scotland and Ireland. 



