. Botany for high schools and colleges. Botany. FILIGE8. 377 furnislied with a usually incomplete, nearly vertical, or rather oblique ring. Receptacle prominent, barrel-shaped (Fig. 265). Tree-ferns. Genera three {Cyathea, Hemitdia, and Alsophila); species 150, mostly tropical and subtropical. 4. Polypodiacem. — Sporangia stalked, splitting transversely, fur- nished with a usually incomplete vertical ring. Receptacle not prom-. FiG. 263. Fig. 264. Fig. 265. Fig. 263.—Portion of a leaf of Gleich&nia, with a sorus, a ; b, a sporangium.—Af- ter Hooker. Fig. 264.—Portion of a leaf of Trichoina
. Botany for high schools and colleges. Botany. FILIGE8. 377 furnislied with a usually incomplete, nearly vertical, or rather oblique ring. Receptacle prominent, barrel-shaped (Fig. 265). Tree-ferns. Genera three {Cyathea, Hemitdia, and Alsophila); species 150, mostly tropical and subtropical. 4. Polypodiacem. — Sporangia stalked, splitting transversely, fur- nished with a usually incomplete vertical ring. Receptacle not prom-. FiG. 263. Fig. 264. Fig. 265. Fig. 263.—Portion of a leaf of Gleich&nia, with a sorus, a ; b, a sporangium.—Af- ter Hooker. Fig. 264.—Portion of a leaf of Trichoinanes, a, with five sori; b, a sporangium.— Aftf r Hooker. Fig. 265.—Vertical section of a sorus, a, of Alsophila, showing the cylindrical re- ceptacle ; 5, a sporangium.—After Hooker. inent (Figs. 257& to 261). Genera fifty (Acrostichum, Polypodium, Adiantum, Pteris, A,splenium, Scolopendriu7n, Aspidrim, Cysiopteris, etc.); species 2000, widely distributed throughout the world, 5. OsmundacecB.—Sporangia stalked, splitting vertically, furnished with only a faint horizontal bar, instead of a ring (Fig. 266). Genera two {Osmunda and Todea); species ten to twelve, widely distributed in north and south temperate re- gions. 6. Schizceacece. — Sporan- gia sessile, splitting vertical- ly, crowned by a complete small annular horizontal ring (Fig. 267). Genera five {ScMzcea, Anemia, Lygodium, etc.); species sixty, mostly natives of the warm regions of America and Asia, Economically the true Ferns are of comparatively little value. The pulpy interior of the stem of a tree-fern {Cyatliea medullaris) growing in the Pacific islands furnishes an important article of food to the natives. In Australia the underground stems of Pteris aquilina supply an indifferent food. A few species are of doubtful value as astringent medicines. The long woolly hairs of certain species ot. Please note that these images are extracted from scanned page images that may have been digitally enha
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