622 maxon: a new polystichum 



Polystichum Dudley i was figured by D. C. Eaton as Aspidium 

 aculeatum var. angulare in the second volume of the Ferns of North 

 America,^ but the illustration is defective in failing to show the pin- 

 nules as distinctly stalked and copiously clothed with filiform scales, 

 and as sufficiently oblique. In papyraceous texture, fully bipinnate 

 blades (which are only slightly narrowed at the base), stalked pin- 

 nules, and terminal or subterminal sori the relationship of P. Dudleyi 

 is clearly with the European plant called Polystichum. angulare by most 

 English botanists, Aspidium aculeatum B. aculeatum by Milde, As- 

 pidium lohatum /S angulare by Luerssen, and Polystichum aculeatum by 

 Christensen, the last author maintaining P. lohatum (Huds.) Presl as 

 specifically distinct; but, inordinately variable as the European plant 

 is, P. Dudleyi is at once distinguished from that by its invariably oblique, 

 less strongly awned, and more copiously filiform-paleaceous pinnules, 

 and by its strikingly fimbriate-ciliate indusia. The enlarged superior 

 basal pinnules are a constant feature not seen in most forms of P. 

 aculeatum {P. angulare); in this particular alone P. Dudleyi suggests 

 P. lohatum (the P. aculeaturn or P. aculeatum var. lohatum of British 

 botanists, Aspidium lohatum genuinum of Luerssen, Aspidium aculeatum 

 A. aculeatum of Milde), a plant otherwise very different in its barely bi- 

 pinnate blades (these strongly narrowed downward), its sessile to ad- 

 nate, less incised segments, its dorsal sori, and its harsh, rigid texture. 

 It is worth noting also that, so far as specimens at hand and descrip- 

 tions indicate, the European plants have the indusia entire or, at 

 most, minutely erose, a marked departure from the conspicuously 

 long-ciliate indusia of P. Dudleyi. Although the proper classification of 

 the very nmnerous European forms of this alliance is admittedly a 

 difficult matter, it appears that related American plants are almost 

 without exception specifically distinct from them. In the present in- 

 stance P. Dudleyi may be regarded as an analogue of the European P. 

 aculeatum, just as P. californicum (D. C. Eaton) Diels, is to a certain 

 extent, a Cahfornian counterpart of P. lohatum. 



2 PI. 02, f. 7. 1879. 



