THE POLYPODIES. 203 



mon beech fern and the fronds are more erect. They 

 are also thinner with fewer hairs and scales. The 

 crushed fronds of both species emit a peculiar ferny odour 

 from the minute glands scattered over their blades. 

 This odour differs slightly with the species and. one 

 with an acute sense of smell might bring it into use 

 in identifying them. 



In the matter of range hexagonoptera again shows a 

 difference. It is a southern species, extending from the 

 Gulf of Mexico to Canada. It has not as yet been 

 found in the Old World. The angular wings of the 

 rachis have suggested the specific name and also the 

 common one of six-angled polypody. Specimens inter- 

 grading between this and the common beech fern are 

 said to be occasionally found. 



The Oak Fern. 



Should the collector in crossing a piece of rich moist 

 woods find nestling among the violets, mitreworts and 

 trilliums, a tiny fern with a blade " like three fronds 

 in one " that would pass for a good miniature of the 

 bracken, he will be warranted in concluding that it is the 

 oak fern (Phegopteris Dryopteris). The rootstock is like 

 that of the beech fern slender and creeping and the 

 fronds are produced all summer. They sometimes at- 

 tain a height of more than fifteen inches but are usually 

 much shorter. The stipes are very slender and the 

 blade triangular, ternate, and of a delicate shade of yel- 

 low-green. At the top of the stipe the blade divides 

 into three nearly equal, triangular, stalked divisions, each 

 of which is pinnate with sessile, deeply pinnatifid, blunt- 

 lobed pinnae. The middle division of the blade is slightly 

 the largest and the pinnules of the lateral divisions are 



