. Lichens. Lichens. STRATOSE THALLUS 93 under surface or are confined to special areas. RosendahP has described their development in the brown species of Parmeliae: the under cortex in these lichens is formed of a cellular plectenchyma with thickish walls ; the rootlets arise by the outgrowth of several neighbouring cells from some slight elevation near the edge of the thallus. Branching and interlacing of these growing rhizinal hyphae follow, the outermost frequently spreading outwards at right angles to the axis, and forming a cellular cortex. The apex of the rhizoid is generally an enlarged
. Lichens. Lichens. STRATOSE THALLUS 93 under surface or are confined to special areas. RosendahP has described their development in the brown species of Parmeliae: the under cortex in these lichens is formed of a cellular plectenchyma with thickish walls ; the rootlets arise by the outgrowth of several neighbouring cells from some slight elevation near the edge of the thallus. Branching and interlacing of these growing rhizinal hyphae follow, the outermost frequently spreading outwards at right angles to the axis, and forming a cellular cortex. The apex of the rhizoid is generally an enlarged tuft of loose hyphae involved in mucilage (Fig. 53), a provision for securing firmer cohesion to the support; or the tipsspread out as a kind of sucker. Not unfrequently neighbouring "rootlets" are connected by mucilage at the tips, or by outgrowths of their hyphae, and a rather large hold-fast sheath is formed. In species of Peltigera (Fig. 54) the rhizinae are confined to the veins or ridges (Fig. 55); they are thickish at the base, and are generally rather ^^i*^'-^. 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 Smith, Annie Lorrain. Cambridge, At the University Press
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishercambr, bookyear1921
