470 Eaton : Ptekidophytes observed in Florida 



swamp and sent a few pinnae only to Mr. J. H. Ferriss. Mr. 

 Layne's plants came from Fahkahatchie near 'Everglade, Lee 

 County, and his guide informed me that it grew on cypress knees. 

 This magnificent fern is a close competitor of Acrosticlatm ex- 

 celsitm in size. There are perhaps 40 large plants and many 

 seedlings of it growing on cypress knees in the tangled hammock 

 north of the old Miami pumping station. My first plants were 

 only 1.5-2 dm. high, but were sufficient to convince me that 

 here was an unreported fern and to spur me to an extended search, 

 which was rewarded by plants with fronds 28.5 dm. long by 9 dm. 



broad. 



The rootstocks are thick, covered with bases of old fronds, 



several inches long, clinging to the older, often decaying and hu- 

 mus-filled, cypress knees by numerous roots. They were usually 

 above the flood line, and wound over the small knees, about a foot 

 from the forest floor.* In no instance did I see one rooted in soil. 

 The fronds are rather firm, but not coriaceous. The bulbils are 

 formed at the apex of an appressed basal nerve, on either or both 

 sides of the petiolule of a pinna. As the nerve thickens to cor- 

 respond with the size of the plantlet the latter can not become 

 detached and can only take root by the bending of the parent 

 frond toward the earth. The plantlets thus grow in situ, sending 

 out roots and fronds, the latter sometimes a foot long, well devel- 

 oped and fructiferous. The stipes and veins are smooth and 

 stramineous save for a narrow chestnut axillary band at base of 

 each pinna. 



The sterile pinnae are somewhat narrowed at base and 

 broadly and obliquely cuneate, or more rarely narrowed and 

 somewhat rounded to the short petiole. The fertile are usually 

 more sharply cuneate, the lower margin starting at the point of 

 insertion and somewhat rounded to the angle, the upper margin 

 starting 2-4 mm. from the axil and running straight or somewhat 

 incurving to the angle, making the base oblique. The pinnae of the 

 sterile fronds are often broadest near the middle, but .the fertile 

 usually attain their greatest width 12-16 mm. from the base and 



long-attenuate. 



very 



The primary veinlets spread nearly horizontally at first, 



