26 



THE A^IERICAX BOTANIST 



AMiile the polypoch' reaches its finest development on the 

 surfaces of rocks, it does not demand any special kind and 

 occasionally spills over onto stumps and roots of trees if they 

 are fairly dry. In fact, the first polypodies I had the pleasure 

 of finding, Avere on roots of trees at the base of a limestone clift'. 

 but they were poor specimens indeed, compared with the thou- 

 sands of sturdy plants I found growing on the top of great 

 masses of conglomerate two years later. How they obtained 

 food for such vigorous growth I cannot understand for many 

 of the rocks were bare of soil and at best had but a scanty 

 covering, but I have never seen more luxuriant growth and 

 one need not be a sage to find a little sermon in a polypody- 

 coA^red rock. 



The fronds of the polypody are rather odd in outline, 

 thick and leathery in texture and remain green all winter. 

 They grow from a slender rootstock that creeps over the sur- 

 face of the rocks and have a short slender stipe and narrowly 

 pinnate or pinnatifid blade. The pinnules are linear, rather 

 blunt and sometimes toothed, and bear on the back a double 

 row of large yellowish sori mostly on the upper part of the 

 frond. The fruit dots have no indusium and are borne on the 

 ends of the veins. This species has a superficial resemblance 

 to the Christmas fern (Polystichinii acrosficJioides) hut the 

 differences are many and easily found when one begins to 

 look for them. 



Our present species is found nearly throughout Xorth 

 America and has several varieties, of which Cainhricum, 

 originally found in A\'ales and but rarely in this country, is 

 the most noted. This has a frond much broader than the type 

 and the pinnae are cut nearly to the midrib. Other varieties 

 are angustuin with narrow toothed pinnules, rotundatiiin, with 

 short rounded pinnules, and cristatiim with pinnules forked 

 and crested. All may be looked for with the type, though 

 perhaps not often found. 



