. Our native ferns and their allies [microform] : with synoptical descriptions of the American pteridophyta north of Mexico. Ferns; Fougères. l6 OUR NATIVE FERNS AND THEIR ALLIES, ing a single sorus. The veins extend nearly at right angles to the midvein, are free, and usually forked. 46. Camptosorus.—The walking-leaf has oblong or linear indusiate sori, which are irregularly scattered and borne partly on veins parallel to the midvein, and partly on those that are oblique. Those near the midvein are single, those toward the margin are often approximate in pairs and often form crooked lines. Th
. Our native ferns and their allies [microform] : with synoptical descriptions of the American pteridophyta north of Mexico. Ferns; Fougères. l6 OUR NATIVE FERNS AND THEIR ALLIES, ing a single sorus. The veins extend nearly at right angles to the midvein, are free, and usually forked. 46. Camptosorus.—The walking-leaf has oblong or linear indusiate sori, which are irregularly scattered and borne partly on veins parallel to the midvein, and partly on those that are oblique. Those near the midvein are single, those toward the margin are often approximate in pairs and often form crooked lines. The veins are everywhere copiously reticulated. 47. Phearopteris.—In this genus the sori are round and naked as in Polypodium, with which this genus was formerly united. The sporangia spring from the back of the veins in- stead of the apex, as in the latter genus, and the veins are free except in the § Goniopteris, in which they are more or less united. 48. Dryopterls is largely represented in our limits by two well marked groups which it is best now to regard as distinct genera, and two others with characters scarcely less distinct, containing each a single species. In all the sori are roundish, and borne on the back of the veins or rarely at their apex. In Dryopteris the indusium is cordato-reniform or orbicular with a narrow sinus. This at first covers the sorus and is attached by its margin, but later bursts away at the margin but remains attached at the sinus. In some species in this section the indusium becomes shrivelled before Fig. 8. — Under the fruit matures, and in this condition might mJnt°of i?r}l5/"/J be mistaken for a non-indusiate species (Fig. 8). , with In Polystlchum the indusium is orbicular eight son. », the indusium. Magrni- and peltate, being fixed by the centre; the veins fied. (After Sachs.) / • ^ xV are free, as m § Nephrodium. In Phanerophlebia the indusium is the same as in POLY- STICHUM, but the veins tend to unite near the
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