. A textbook of botany for colleges and universities ... Botany. 740 ECOLOGY arrangement of the parts. For example, in Raoulia (fig. 1060) and in other alpine or arctic cushion plants, the short stems are so closely packed together that only the tips are exposed. Cushions are formed by various mosses (as Leucohryum, Bartramia, and Dicranum) and by some lichens (as Cladonia rangiferina, fig. 898), but among seed plants the habit is rare outside of inclement climates. An additional advantage from. Fig. 1063. â A spherical cactus (Echitiocactus ]Vislizen{), representing an extreme con- trast to a
. A textbook of botany for colleges and universities ... Botany. 740 ECOLOGY arrangement of the parts. For example, in Raoulia (fig. 1060) and in other alpine or arctic cushion plants, the short stems are so closely packed together that only the tips are exposed. Cushions are formed by various mosses (as Leucohryum, Bartramia, and Dicranum) and by some lichens (as Cladonia rangiferina, fig. 898), but among seed plants the habit is rare outside of inclement climates. An additional advantage from. Fig. 1063. â A spherical cactus (Echitiocactus ]Vislizen{), representing an extreme con- trast to a thin-leaved tropical evergreen, since it has a minimum transpiring surface in pro- portion to its volume; note the numerous recurved spines. ââ Photograph by Fuller. dwarfness is increased ground protection; as a consequence, transpira- tion is still further reduced and temperature changes are less rapid. Perhaps the advantages of proximity to the ground are best realized in rosette herbs, whose leaves often are closely appressed to the soil (fig. 1036). A third and perhaps the greatest advantage in dwarfness is seen where the latter is most in evidence, namely, in alpine and arctic regions. There it makes possible protection by snow, and con- sequently there is a suspension of transpiration during the very months when it would be most dangerous because of the cessation of absorption; furthermore, snow covers protect greatly from 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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