FERN'S. 



157 



choides) shown in fig. 131. The leaves are the most prominent 

 part of the plant, as is the case with most if not all our native 

 ferns. The stem is very short and for the most part under the 

 surface of the ground, -while the leaves arise 

 very close together, and thus form a rosette 

 as they rise and gracefully bend outward. 



The leaf 

 is elongate 

 and re- 

 minds one 

 somewhat 

 of a plume 

 with the 

 pinnae ex- 

 tending in 

 two rows 

 on oppo- 

 site sides 

 of the midrib. These 

 pinnae alternate with 

 one another, and at the 

 base of each pinna is a 

 little spur which projects 

 upward from the upper 

 edge. Such a leaf is said 

 to be pinnate. While all 

 the leaves have the same 

 general outline, we notice 

 that certain ones, especi- 

 ally those toward the centre 

 of the rosette, are much 

 narrower from the middle portion toward the end. This is 

 because of the shorter pinnae here. 



261. Fruit "dots" (sorus, indusium). — If we examine the 

 under side of such short pinnse of the Christmas fern we see that 



Fig. 131. 

 Christmas fern (Aspidium acrostichoides). 



