. A textbook of botany for colleges and universities ... Botany. REPRODUCTION AND DISPERSAL 815 ( Marsilea, Salvinia, and Azolla) and in SelagineUa and Isoetes there are two kinds of spores, namely, small spores or microspores, and large spores or megaspores; such a condition is known as keierospory (fig. 303). Upon germination the microspores give rise to male plants and the 1129. ^(128 Figs. 1128, 1129. — Reproduction by asexual spores in a fern (Aspidium): 1128, a leaf segment (pinnule) with fruit dots (sori), each with a shield-shaped cover (indusium); 1129, a cross section through a s
. A textbook of botany for colleges and universities ... Botany. REPRODUCTION AND DISPERSAL 815 ( Marsilea, Salvinia, and Azolla) and in SelagineUa and Isoetes there are two kinds of spores, namely, small spores or microspores, and large spores or megaspores; such a condition is known as keierospory (fig. 303). Upon germination the microspores give rise to male plants and the 1129. ^(128 Figs. 1128, 1129. — Reproduction by asexual spores in a fern (Aspidium): 1128, a leaf segment (pinnule) with fruit dots (sori), each with a shield-shaped cover (indusium); 1129, a cross section through a sorus, showing the indusium (i) and long-stalked sporangia (s); 1129 considerably magnified. — After Wossidlo. megaspores to female plants, whereas the spores of most homosporous ferns give rise to plants that bear both male and female organs. The spores of most pteridofihytes are scattered by the wind, and they are well fitted for such dispersal by their small size, by their resistance to wetting (particularly in Lycopodium), and by their elevation upon foliage leaves or special stalks (figs. 266, 332, 353). Fern sporangia dehisce in a somewhat complicated manner (p. 351), a ring of dead. 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; Barnes, Charles Reid, 1858-1910, joint author; Cowles, Henry Chandler, 1869- joint author. New York, Cincinnati [etc] American book company
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