HELPS FOR THE BEGINNER.* 



Poly stick u m acrostichoides 

 (The Christmas fern), 

 nate fronds are also known to occur. 



III.— The Christmas Fern. 



IF there exists in^the Northern or 

 Eastern States a stroller in the 

 winter woods who is not famil- 

 iar with the sight of the Christmas 

 fern, there must be something 

 wrong with his powers of observa- 

 tion, or the locality in which he 

 walks. From October to March 

 the sturdy dark green fronds are 

 most conspicuous objects, espec- 

 ially in rocky woods, and in the 

 warmer parts of the year they are 

 just as abundant, though perhaps 

 less noticeable amidst the other 

 vegetation. 



The Christmas fern (Poly st ic hum 

 acrostichoides) may be known at 

 once from all our other ferns by 

 the curious habit it has of bearing 

 its fruit dots on the much-reduced 

 upper portion of the fronds. On 

 these pinnules they are so thickly 

 set as to completely cover the 

 under surface. Sterile fronds may 

 frequently be mistaken for those 

 of the polypody, but it should be 

 remembered that this species dif- 

 fers from the polypody in being 

 completely pinnate with stalked 

 pinnules, each of which is eared 

 on the upper edge at base. 



A form is frequently found in 

 which the pinnules are deeply ser- 

 rate and the fruit dots not confined 

 to the diminished upper portion, 

 but borne on the tips of the lower 

 pinnae as well. This is the variety 

 incision. Forms with twice pin- 



'Begun in Juiy, iqoo. The series will include all our American ferns 



