. Our native ferns and their allies [microform] : with synoptical descriptions of the American Pteridophyta north of Mexico . Ferns; Ferns; Pteridophyta; Fougères; ; . I j 14 OUR NATIVE FERNS AND THEIR ALLIES. ing the sori at or near the ends of the veins, covered by an in- dusium formed of the margin of the frond. In § Adiantopsis the indusia are distinct, and confined to a single veinlet. One of our species varies from the typical species of this section, and has even been assigned to a separate genus. In ij the indu-. e.—i'ieiis ion,:ijoUa L. En- sia are more or less confluen
. Our native ferns and their allies [microform] : with synoptical descriptions of the American Pteridophyta north of Mexico . Ferns; Ferns; Pteridophyta; Fougères; ; . I j 14 OUR NATIVE FERNS AND THEIR ALLIES. ing the sori at or near the ends of the veins, covered by an in- dusium formed of the margin of the frond. In § Adiantopsis the indusia are distinct, and confined to a single veinlet. One of our species varies from the typical species of this section, and has even been assigned to a separate genus. In ij the indu-. e.—i'ieiis ion,:ijoUa L. En- sia are more or less confluent but vein-like "receptacid under the nuirgi-not Continuous, usually extending larfjed segment ol pinna, showing the vein-like rece nai inciusiuin. over the apices of several veinlets. In § Physapteris the ultimate segments are bead-like, and the indusium is continuous all round the margin. § ALEURrroPTRRiS has the fronds farinose below, and in- cludes a single species somewhat doubtfully assigned to our limits. 38. Cryptogramme has dimorphous fronds, the margins of the fertile being closely rolled toward the midvein, thus cov- ering the confluent sori. At maturity these open flat in order to discharge the spores. 39. PeMaea has representatives of three sections within our limits, all agreeing in possessing intramarginal sori, which finally became confluent and form a marginal lineco\ered by an indusium formed of the margin of the frond. § Cheil()PLECT()N includes herbaceous species with visible veins and broad indusia. § Allosorus includes coriaceous species having wide indusia, while § Platyloma includes species similar in texture, but with extremely narrow indusia and l)road scgirients. 40. Ceratopteris is an anomalous genus from southern Florida, having a few sori arranged on two or three veins par- allel to the midvein, and covered by the broadly reflexed margin of the frond. 41. Lomaria (Fig. 7) stands intermediate between those genera, in whicli there is a
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