SPINULOSE, OR COMMON WOOD-FERN. 



almost tripinnate, and the frond has a generous breadth which 

 distinguishes the variety from those already described. The 

 sori are either apical, sub-terminal or medial, seated on the 

 lowest anterior veins or on short veinlets derived from them, 

 the position varying according to the size of the pinnules. 

 In American specimens the indusium is smooth, so far as I 

 have observed, and the spores are irregularly winged or 

 cristate. In the plant of Europe the indusium is said to be 

 usually glandular. In writing the Synopsis Filicum, Swartz 

 at first united this form with A. spinulosum, but in the 

 addenda he separated the two, in which he was followed 

 for a long time by most writers. I do not know that the 

 first edition of the British Flora (1830) is the earliest pub- 

 lication in which A. dilatatum is made a variety of A. 

 spinulosum, but it is the earliest that I can find. 



Var. dumetorum {Aspidium dumetorum, Smith) is a form 

 of var. dilatatum having dwarfish deltoid-ovate compactly 

 bipinnate fronds and large pinnules, the inferior basal ones 

 of the lowest pinnae not much elongated. It is found in 

 mountainous parts of Europe ; but I have seen nothing 

 exactly corresponding to it in America. It seems to be 

 only var. dilatatum dwarfed and compacted by exposure to 

 the sun, and will probably be found ere long in northern 

 New England or Canada. Other European subrvarieties are 

 mentioned by Moore and Milde, and the student is referred 

 to their writings for descriptions or figures of them. 



Var. Boottiiy Gray, has been variously referred to A. 



