Ebony Spleenwort 79 



wholly upon latter branch or extending along the veinlet of the 

 latter (when one is present), next the midvein, opening toward 

 the midvein: indusia whitish, dehcately membranous, the mar- 

 gin erose or shghtly ciliate-erose. 



Spores brown, covered with anastomosing ridges. 



Habitat. Dry places exposed to the sun or partly shaded; 

 usually near or on rocks. In old fields and pastures, among 

 stones by the roadside, etc. 



Range. Florida to Maine and southeastern Ontario, west to 

 Texas and Colorado. 



Asplenium platyneuron (Linnaeus) Oakes; D. C. Eaton, Ferns N. Am. 

 i: 24. 1878. 



Acrostichum platyneuros. Linnaeus, Sp. PI. 1069. 1753. 

 Asplenum ebeneum, Aiton, Hort. Kew. 3: 462. 1789. 



The blade of the leaf first produced by the young plant of 

 Asplenium platyneuron is usually either obcordate, or bilobed 

 with each of the two lobes slightly bilobed. If the first, it con- 

 tains a once-forked vein; if the second, a twice-forked vein, each 

 of the four veinlets occupying one of the lobes. Another very 

 young leaf is trilobed. It contains a vein which is simple at 

 apex, occupying the central lobe, and which bears two simple 

 branches below, each occupying one of the lateral lobes. The 

 leaf-blade becomes next somewhat more complexly lobed and 

 its midvein develops farther. Pinnas are then gradually formed, 

 in the same manner as in ^. trichomanes.* In A. trichomanes, 

 however, the pinnae are often opposite, whereas in A. platyneuron 

 they are nearly always alternate. 



The leaf's petiole is green at first but soon begins to change 

 color, although not, at least noticeably, as soon as in ^. tricho- 



* See page 65. 



