SPINULOSE, OR COMMON WOOD-FERN. 



A. spinulosum genuinum, indicating the fact that the basal 

 pinnules are shorter than the next. Dr. Gray also examined 

 the Willdenovian specimens of intermedium, and his notes 

 show that he recognized in them what we now call var. 

 intermedium. Willdenow's words " pinnulis pinnatifido-incisis " 

 also point towards var. intermedium; since of A. spinulosum 

 he says : " pinnulis inciso-dentatis." It is therefore right to 

 keep for this form the time-honored name of intermedium; 

 and to consider it a variety of A. spinulosum, because neither 

 in the form and details of the frond, the position of the sori, 

 nor the glandulosity of the surface and indusia can any specific 

 distinction be fairly discovered. 



Var. dilatatum has dark-green deltoid-ovate or broadly 

 ovate fronds often considerably larger than in the other 

 forms : Milde gives three feet as the extreme length, but 

 such fronds are rarely preserved for herbarium specimens. 

 The pinnae diverge from the rachis at from sixty to eighty 

 degrees. The lowest ones are frequently but not invariably 

 longest, but always broadest : in one example from Mount 

 Mansfield they are eight or nine inches long, and five 

 inches wide at the base. They are broadly triangular, 

 nearly twice pinnate, the secondary rachis wingless and the 

 tertiary very narrowly winged, and the inferior basal pin- 

 nules are over three inches long. The inferior basal pinnules 

 are longer than the next ones in this form, but the supe- 

 rior basal pinnules are shorter than the next. The pinnules 

 generally are so deeply pinnatifid as to render the frond 



