io6 THE CHRISTMAS AND HOLLY FERNS. 



The Christmas Fern. 



To the hunter, the trapper and the rambler in the 

 winter woods, the Christmas fern (Polystichum acrosti- 

 choides) is a familiar species. In summer it is not espe- 

 cially noticeable, but in the snowbound season, the 

 cheerful, fresh-looking fronds are sure to attract the eye. 

 It is a most abundant species and suitable localities within 

 its range where it cannot be found are exceedingly rare. 



All the Christmas fern's fronds are produced early in 

 spring. They rise in circular clumps from a stout root- 

 stock and when uncoiling are thickly covered with, silky- 

 white scales that make them conspicuous objects in the 

 vernal woods. As the fronds mature, the scales turn 

 brow'n and many remain upon rachis and stipe, especially 

 the latter, through the season. The fronds occasionally 

 reach a height of three feet, and are thick, narrowly 

 lanceolate, acute and once pinnate. The numerous 

 narrow pinnules have finely serrate margins and are 

 arranged alternately on the rachis. Each has a triangu- 

 lar ear on the upper side at base. The fertile fronds are 

 taller than the sterile and differ in having the upper 

 third or half suddenly decreased in size, this part bear- 

 ing the sporangia. The sori are arranged on the under 

 surface in two or more rows lengthwise of the pinnules 

 with two other short rows on the earlike projections. 

 They are partly formed before the fronds unfurl and 

 ripen early in the year, being among the first of our 

 species in this respect. The sporangia early push out 

 from beneath the peltate indusia and make the fruiting 

 pinnules look like little assemblages of tiny brown ant- 

 hills. One of these pinnules is shown in the Key to the 

 Genera. 



