. Plants; a text-book of botany. Botany. I'TEKIDOPIIYTES 145 margin (Figs. 135, 120), which may be called a "false in- ; It is evident tliat siicli leaves are doing two distinct kinds of work—chloropliyll work and spore formation. This is true of most of the ordinary Ferns, but some of them show a tendency to di- vide the work. Certain leaves, or certain leaf-branches, pro- diice spores and do no chloro- phyll work, while others do chlorophyll work and produce no spores. This differentia- tion in the leaves or leaf-re- gions is indicated by appro- priate names. Those leaves w
. Plants; a text-book of botany. Botany. I'TEKIDOPIIYTES 145 margin (Figs. 135, 120), which may be called a "false in- ; It is evident tliat siicli leaves are doing two distinct kinds of work—chloropliyll work and spore formation. This is true of most of the ordinary Ferns, but some of them show a tendency to di- vide the work. Certain leaves, or certain leaf-branches, pro- diice spores and do no chloro- phyll work, while others do chlorophyll work and produce no spores. This differentia- tion in the leaves or leaf-re- gions is indicated by appro- priate names. Those leaves which produce only spores are called sporophylls, meaning " spore leaves," while the leaf branches thus set apart are called sporophyll branches. Those leaves which only do chlorophyll work are called/o- liuga leaves ; and such branch- es are foliage branches. As sporophylls are not called upon for chlorophyll work they often become much modified, being much more compact, and not at all resembling the foliage leaves. Such a differentiation may be seen in the ostrich fern and sensitive fern (Onodea) (Figs. 137, 138), the climbing fern {Lygodium), the royal fern {OsminuJa), the moonwort {BotrycUum) (Fig. 129), and the adder's tongue {OjMoglossum) (Fig. 130). An ordinary fern sporangium consists of a slender stalk and a bulbous top which is the spore case (Fig. 118, 6). This case has a delicate wall formed of a single layer of cells, and extending around it from the stalk and nearly to. Fig. 125. Leaflets of two common ferns: ,1, the common brake {PUri^)\ B, maidenhair {Adian- 1")/'): both showing sori borne at the margin and protected by the infolded margin, which thns forms a false indusium.—Cald- Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York
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