THE MALE FERN DRTOPTERIS FILIX-MAS 



(3) The pinnules are completely separated, toothed and tapering (unlike D. Borreri). 

 Cf. Fig. 29. 



(4) The margin of the indusium in the young state lies flat on the surface of the leaf 

 and is not tucked under the sorus. 



(5) The sori are fairly large, the average diameter being 1-5 mm. (contrast with 

 D. abbreviata). 



(6) The ramenta on the rachis are sparse. 



^* ^"^ «r* 





D. Filix-mas n=82 



Fig. 30. Diagram to explain Fig. 35. x 1500. 



In contrast with this hedgerow type, in which it is not at the moment profitable to 

 distinguish varieties, though with fuller genetical knowledge this could perhaps be 

 done, it is important to separate a smaller mountain form with half the chromosome 

 number (i.e. 2^ = 82, ^ = 41, cf. Fig. 31), which is, nevertheless, also sexually repro- 

 duced (Fig. 42^) and can be made to hybridize with the other (see p. 49 below). In 

 many Floras it goes by the name of 'var. abbreviata Newman', and has been recorded 

 from most of the mountainous regions of England, Scotland and Wales, and from two 

 localities in Ireland ; it is also said to have been found in central France. 



The principal characters by which D. abbreviata * can be distinguished in the field are 

 as follows : 



( 1 ) The habitat is that of a mountain plant with a marked preference for the shallow 

 soil of rock crevices or scree; it is only to be found under trees where these have invaded 

 a previously exposed site. 



(2) Its stature is smaller than that of D. Filix-mas and the form of the stock is much 

 more tufted owing to frequent branching. A stock with a single crown is only usual 

 among young plants. 



* Some other details are enumerated by Wollaston (1875). 



46 



