THE DWARF SPLEENWORT. 



A splen ill m p u milii in. 



THOSE who have confined their fern studies to a hmited 

 legion often have an erroneous conception of the range 

 in form of genera that makes collecting in any distant country 

 a series of surprises. Sometimes the impression of a genus is 

 correct, as when we assume from experience with the cinna- 

 mon fern, the interrupted fern, and the royal fern, that all the 

 Osmundas are large, but we are as likely to go astray in our 

 judgment as we do when v^•e infer from a few 'lirninniive speci- 

 mens that all the filmy ferns are as small and delicate. In 

 general the smaller the genus, the greater is the likelihood that 

 the species composing it are all quite similar ; indeed one of the 

 reasons brought forward for separating our common boulder 

 fern {Dicksonia pilosiitsciila) from the other Dicksonias was 

 that it differed from the others so much in size an habit. 



In any large genus, howe\-er, it is usunl to find a wide 

 range in the size, shape and cutting of the fronds. The species 

 are likely to begin with entire fronds, shade into pinnatifid or 

 pinnate species and end with forms that are often many times 

 compound. So, too. in the matter of size, there are species, 

 small and inconspicuous, almost lost among the other herbage 

 of their haunts and others that reach sizes that render it im- 

 possible for them to escape notice. After one has spent a day 

 collecting polypodies so small that it is necessar}' to carefully 

 examine the mossy tree-trunks upon which they grow in order 

 to find them at all, it is an impressive contrast to find on the 

 way home some species such as Polypodium crassifolium with 

 fronds like broad-swords. 



Nor do size and delicate cutting have any necessary rela- 

 tionship. The large fronds are as likely to be deeply cut as 

 are those of small species but no more so. In the case I have 

 mentioned both forms happen to have entire fronds, though 

 one is possibly fifty times larger than the other., Size very fre- 



74 



