38 FERN FAMILY 



In general habit this species closely resembles the Rigid 

 Wood-fern, but the indusium is so characteristic that they are 

 placed in different genera. It forms ornamental clusters on 

 many of our talus slopes. In addition to the species, we 

 have two of its varieties, as follows : Var. imbricans Maxon, 



Polystichum munitum nudatum form Var. imbricans 



which has been collected at Staircase Falls, etc., is smaller 

 than the species; fronds broader at base; pinnae more 

 crowded, ascending-imbricate and more oblique to the rachis; 

 stalks scaly at base but otherwise mostly naked; sori near 

 the margin and confined to the upper pinnae. The other 

 variety (Aspidium munitum nudatum Eat., apparently not 

 transferred to Polystichum) was first described from a speci- 

 men collected near Nevada Falls, and has since been found 

 also on the Ledge Trail and along the Wawona Road. Its 

 fronds are smaller than in the species, the stalks less chaffy; 

 the pinnae fewer, short and broad, and farther apart; the sori 

 confined to a few upper pinnae. 



P. aculeatum Roth., has been reported from our district. 

 If found, it may be known from P. munitum by the fronds, 

 which are 2-pinnate, or if simply pinnate then with deeply 

 cut pinnae. (Aspidium aculeatum Swartz.) 



teeth. 



12. ASPIDIUM. Wood-fern. Shield-fern. 



rigidum var. argutum Eat. Rigid Wood-fern. Stalks 

 3 to 12 in. long, chaffy. Fronds 

 dark-green and smooth above, 

 paler and somewhat glandu- 

 lar beneath, 8 to 24 in. long, 

 3 to 10 in. broad, ovate-lance- 

 olate in outline, 2-pinnate; 

 lowest pinnae broadest; seg- 

 ments oblong, incised or 

 doubly toothed with spine-like 

 Sorus large, round; indusium kidney-shaped or round 



