12 



POLYPODIACEAE 



1. A. excelsum Maxon. Leaves closely tufted, ascend- 

 ing or erect, stiff, 1.5-4 m. tall, petiole unarmed, stout, 

 deeply furrowed; blade much 

 longer than the petiole; leaflets 

 usually numerous, the blades thick, 

 lanceolate to linear-lanceolate, the 

 larger ones mostly 2-3 dm. long, 

 sometimes more, deep-green, stiff, 

 approximate or imbricate, short- 

 stalked; areolation fine, slightly 

 oblique to the mid-rib: sporangia 

 covering the lower surface of all 

 the leaflets of the spore-bearing 

 leaves.- (LEATHER-FERN.) Fresh- 

 water marshes, low prairies, and" 

 wet hammocks. Figure 5, reduced. 

 This fern as far as mass is con- 

 cerned has the largest leaves of 

 any of our fern-plants. In favor- 

 able localities leaves often meas- 

 ure nearly four meters in length. 

 Away from the influence of salt-water it reaches its 

 greatest development, both in size and quantity. In the 

 prairie-like outlets of the Everglades and far north about 

 Lake Okeechobee areas acres in extent are covered with, 

 a magnificent growth of this fern. The tangled masses 

 of rootstocks and the close-set stout leaf-stalks make 

 these thickets almost impenetrable. It thrives best in 

 places fully exposed to the sun. In Eoyal Palm Ham- 

 mock it is common among the shrubbery around the 

 edge of the hammock and it also occurs more sparingly 

 in the low places in the forest. This plant is common 

 in insular and continental tropical America, and was 

 discovered in Florida in the earlier half of the last cen- 

 tury. Besides occurring in our range it extends north- 

 ward into the lake region of peninsular Florida. 



