64 WAYSIDE AND WOODLAND FERNS. 



of which the upper basal pinnule of each pinna is larger than 

 its fellows (Plate 70). A variety of this (var. lonchitidoides) has 

 still narrower fronds and only a few of the pinnae are divided 

 into pinnules. This variety has in consequence frequently been 

 mistaken for the Holly-fern. We are inclined to suggest that 

 it may possibly be a hybrid between Aspidium aculeatttm and 

 Aspidium lonchitis. 



Soft Prickly Shield-fern (Aspidium angiilare). 



There can be little doubt that this is only another sub-species 

 of the preceding, but it is so commonly regarded as distinct, 

 that we have given it a separate heading. In general structure 

 the two are alike with the exception that the material of which 

 the frond is composed is in the one case hard and rigid, in the 

 other soft and yielding. The rootstock is similar, and the 

 clothing of large scales on stipes and rachis the same. The fronds 

 are broader than in A. aculeatum proper, and of a much paler 

 green, the pinnae less crowded, owing to the fact that the 

 pinnules are smaller. The pinnules have also short stalks, and 

 the bases form an obtuse angle ; the teeth are large and end in 

 long hair-like points. (Plates 62, 64, 72.) 



Extreme northern and southern forms of these two Shield- 

 ferns (Aspidium aculeatum and A. angidari) are fairly distinct 

 from each other, but there are so many intermediate forms 

 which only a skilled pteridologist can allocate to this or the 

 other so-called species with confidence, that there can be little 

 doubt that the serious botanist is right who regards them as 

 sub-species with numerous connecting varieties. Sir William 

 Hooker declared many years ago that he had in his herbarium 

 a series of specimens which showed every gradation of variation 

 between the extremes which have been called species, and he 

 had no hesitation in uniting aculeatum, lobatum, and angulare 

 in one species. Climatic conditions doubtless play their part 



