. Botany of the living plant. Botany. 176 BOTANY OF THE LIVING PLANT water-storage, as in the Stonecrop, Aloe, or Onion. In other cases leaf-reduction may go along with a corresponding distension of the stem, which becomes green, and takes over the function of Photo- Synthesis. This is seen in the tropical Euphorbias, and Cactaceae, the former especially on the dry areas of the Old, the latter of the New World (Fig, 132). In some cases the stem swells to an almost spherical form, by which means the greatest possible proportion of bulk to. Fig. 132. Succulent stem and flowers of a Cactus, (.\ft
. Botany of the living plant. Botany. 176 BOTANY OF THE LIVING PLANT water-storage, as in the Stonecrop, Aloe, or Onion. In other cases leaf-reduction may go along with a corresponding distension of the stem, which becomes green, and takes over the function of Photo- Synthesis. This is seen in the tropical Euphorbias, and Cactaceae, the former especially on the dry areas of the Old, the latter of the New World (Fig, 132). In some cases the stem swells to an almost spherical form, by which means the greatest possible proportion of bulk to. Fig. 132. Succulent stem and flowers of a Cactus, (.\fter Figuier.) surface Succulence with a distended form is thus a fre- quent character in Xerophytes. With succulence often goes a spinous development, as Fig. 132 shows. It may doubtless be effective as a defence against herbivorous animals. A thorny character is common in_Xerophyte vegetation, and is a marked feature in dry districts such as the Veldt of South Africa. Finally, many Xerophytes are very deep-rooted. As special instances of this Acanthosicyos and Welwits- chia of south-west Africa may be quoted. Along with succulence and reduction of surface go various other structural modifications. In xerophytic plants there is usually a special dermal develop- ment, with thickened cuticle. It is often covered with wax, giving a glaucous surface. The stomata may be protected by being sunk in deep pits {Fig. 133).. 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 Bower, F. O. (Frederick Orpen), 1855-1948. London, Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
