80 POLYSTICHUM 



CHRISTMAS FERN: 



Polystichum acrostichoides. 

 {Aspidium acrostichoides.) 



Fronds 1 to 3 feet high^ evergreen^ lance-shaped, 

 acute, pinnate; pinnae firm, narrow, finely toothed, 

 eared on the upper side at the base, arranged 

 mostly alternately; fertile fronds taller than the 

 sterile, and differ from them in having the upper 

 fruiting pinnae reduced in size; stipe scaly. 



Fruit dots borne in rows lengthwise of the 

 pinnae, eventually running together, covering the 

 whole of the under surface with the brown spo- 

 rangia. 



The variety incisum may be distinguished by its 

 deeply-toothed pinnae, and by the fruit dots con- 

 tinuing downward on the tips of the ordinary pin- 

 nae, gradually decreasing in number; rarely the 

 pinnae are cut to the midrib. 



The variety crispum has beautifully-crisped and 

 ruffled pinnae. 



Common in rocky woods from Canada to Florida, 

 Mississippi, Arkansas and Wisconsin. 



NOTES. 



