THE OTHER BRITISH FERNS 



which the congested pinnae are the most conspicuous feature, but was also based on the 

 observation that the spores have a highly characteristic surface pattern when seen under 

 the low power of the microscope. This pattern has been described as 'verrucose' 

 (Fig. 1 1 8c) to distinguish it from the very spiny surface met with in other forms of 

 C.fragilis (Fig. ii^a,b) and C. alpina. 



The first reaction to finding a distinctive spore pattern as well as a new chromosome 

 number in C. Dickieana is perhaps to strengthen Newman's conclusion that here is a 

 new species. This is probably the correct interpretation, but before redefining the 

 specific characters it is desirable to make comparisons with material from other sources 

 if possible, and unfortunately the moment this is attempted uncertainty of a different 

 sort sets in. . ^ 



The fronds reproduced on Fig. 1 1 7 have all spineless spores and the low chromosome 

 number (;z = 84). In leaf morphology they are, however, very diverse. The leaf of 



Fig. 118. Spore forms in C>i^/o/^fem. x 250. a. The large spiny spores associated with the high chromo- 

 some number (n= 126) from the leaf of Fig. 1 1 1 Z>. b. Slightly smaller spiny spores associated with 

 the lower chromosome number (« = 84) from the leaf of Fig. 119c. c. C. Dickieana Sim with 

 verrucose spores. 



Fig. 117c is from Kongsvold, Dovrefjell, Norway, from a plant kindly sent to me alive 

 in 1948 by Mrs Gunvor Knaben of Oslo. Kongsvold is the type locality for ' C. Baenitzii', 

 which was described in 1891 by Dorfler, and named after its discoverer, one Baenitz 

 (1891), as a species, on the sole criterion of spineless spores. The leaf of Fig. 117c can 

 hardly be other than C. Baenitzii, and it is not more different from C. Dickieana than is, for 

 example, C. alpina from C.fragilis, though it lacks the congested pinnae of C Dickieana 

 from Scotland. The leaves of Fig. 117^ are, however, of an extremely different type. 

 They are from a plant brought back alive from Greenland in the autumn of 1948 by the 

 Leeds University Expedition to that country. They represent an extreme arctic type, 

 having been laid down in the bud in the original locality which was within five miles 

 of the edge of the permanent ice-sheet which covers central Greenland. Immediately on 

 arrival in Leeds the leaves expanded and within three weeks had given both a cytological 

 demonstration of n = 84 and also proof of spineless spores. To what extent their appear- 

 ance will alter in subsequent years after continuous growth under more temperate 

 conditions cannot be predicted. 



Preliminary search for spineless spores in herbaria has shown them to be distributed 

 on a world scale, although in western Europe they are very infrequent. To the one 

 locality in Scotland (that of var. Dickieana itself) can be added several records of 



118 



