17. POLYSTICHUM Roth. 
Hoc genus Polystichum nomiiiavi ( ex verbis ttoXv 
multufn et (ttlxo^ ordo ) quia f^^uctificationum puncta 
plura in ordines vel scries ordinata plerumque obser- 
vant ur. Roth, 1800. Fl. Germ, 3 : 69, 
Rootstock stout, veiy chaffy. Leaves pinnate, sphiii- 
lose-serrate, Sori large. Inclusium peltate. 
1. P. acrostichoidss (L. C. Rich.) Schott. 
I^ilix nixs foliis integris aitriculatis B mister ; 
Ray, Hist. 1926. 
Poly podium frondc pi^inata lanceolata ^ foliis 
lunulatis ciliato-scrratis. Oron. Fl. Virg. 1 23 . 
JSfephrodium acrostichoides P, C. Pic /i ; yiichx. 
Fl. 2 : 267. 
Aspidium acrostichoides Sw. Syn. Fil. 44. JEat, 
Ferns N. Am. i : 257. t.34 ; in Gray, Man. 689. 
Polystichiim acrostichoides Schott, 1834. Gen. 
Fil. Underw, Nat. Ferns 115; in Britt. Man. 
14. Clute^ Ferns 106., Waters^ Ferns 244. 
D^yopter is acrostichoides Kuntze^ 1891. Revis. 
Gen. 2 : 812* Undci^w, in 111. Fl. i : 14. 
Ckistmas Fern. 
Plante 3-6 dm. high; leaves very chaffy below; pin- 
nae 2-8 cm. 1., auricled on the upper side, oblong-lan- 
ceolate, spinulose-dentate ; upper pinnae fertile, reduced 
