. Our native ferns and their allies [microform] : with synoptical descriptions of the American pteridophyta north of Mexico. Ferns; Fougères. 30 OUR NATIVE FERNS AND THEIR ALLIES. ^- i side), and may be examined with a strong lens. The three di- visions are summed up as follows: "I. Vernation wholly straight. B. simplex Hitch. (Fig. 31). II. Vernation partly inclined in one or both portions. B. lunaria Swz. (Fig. 32), B. boreale Milde, B. neglecttim Wood (Fig. 33), and B. obliquum Michl (Fig. 34) and its allies. III. Vernation wholly inclined, in the fertile frond recurved. B. lanceolatum
. Our native ferns and their allies [microform] : with synoptical descriptions of the American pteridophyta north of Mexico. Ferns; Fougères. 30 OUR NATIVE FERNS AND THEIR ALLIES. ^- i side), and may be examined with a strong lens. The three di- visions are summed up as follows: "I. Vernation wholly straight. B. simplex Hitch. (Fig. 31). II. Vernation partly inclined in one or both portions. B. lunaria Swz. (Fig. 32), B. boreale Milde, B. neglecttim Wood (Fig. 33), and B. obliquum Michl (Fig. 34) and its allies. III. Vernation wholly inclined, in the fertile frond recurved. B. lanceolatum Angs. (Fig. 35), arnd B. Virginianum ; The special characters of each species will be found under the descriptions of the Botrychia later in this work. The cuts will be valuable for reference, and will enable even beginners to identify the species of this complicated genus with compara- tively little difficulty. 84. Fructification.—In this order of plants the fructification consists of sporangia, which^ unlike those of the true ferns, are not reticulated, possess no trace of a ring, open by a transverse slit, and are variously spiked and panicled (Fig. 20). In the adder-tongues {Ophioglossum) the sporangia are large, and cohere in two ranks along the margins of a single spike, opening transversely to discharge their copious sulphur- yellow spores. In the grape-ferns {Botrychium) the sporangia are globular and arranged in double rows along the narrow segments, more or less in panicles. In both genera the sporangia are not developed from the epidermal cells, but arise from a transformation of the interior tissue of the leaf. This, with other characters as clearly defined, serves to separate these anomalous plants from the families of true ferns. 85. Germination.—Among the OPHiOGLOSSACEiE, so far as known, the prothallia are destitute of chlorophyll, develop under ground, and are monoecious. In Botrychium lunaria the prothallium is an ovoid mass of cellular tissue,
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