. The topography of the chlorophyll apparatus in desert plants. Chlorophyll; Desert plants; Plants. KRAMERIA CANESCENS. 21 chlorophyll-bearing tissue is the subepidermal band which extends to the interrupted ring- of hard bast. Chlorophyll is also to be found in the medullary rays and in the outer cells of the pith. The chlorophyll band is composed of a single layer of much-elongated palisade cells, or of a single layer of palisade cells and one tier of nearly cuboid cells which lie within, i. e., towards, the woody Fig. g.—Krameria canescens: A, transverse section of leaf, showing
. The topography of the chlorophyll apparatus in desert plants. Chlorophyll; Desert plants; Plants. KRAMERIA CANESCENS. 21 chlorophyll-bearing tissue is the subepidermal band which extends to the interrupted ring- of hard bast. Chlorophyll is also to be found in the medullary rays and in the outer cells of the pith. The chlorophyll band is composed of a single layer of much-elongated palisade cells, or of a single layer of palisade cells and one tier of nearly cuboid cells which lie within, i. e., towards, the woody Fig. g.—Krameria canescens: A, transverse section of leaf, showing char- acter of the subepidermal palisade cells; B, cross-section of stem, to show structure of cortical chlorophyll band; same magnification as in A; ch. b., cortical chlorophyll band; h. i5.,hard bast; med., medullary rays. With increase in diameter, up to mm. and 30 cm. from the tip, there is no marked change in the appearance of the chlorophyll apparatus of the stem, but in a branch mm. in diameter and 40 cm. from the tip a marked modification is found. This is largely owing to the formation of cork. The phellogen arises in the parenchyma between the hard bast and the cam- bium and by its activities cuts the entire chlorophyll band off from the living portions of the stem. As an immediate consequence the chlorophyll band becomes at once a portion of the cork. In a branch mm. in diam- eter no chlorophyll was found in the wood or pith and none also in the most inner portion of the cortex. It was confined to a layer of cells, or to two layers, immediately beneath the phelloderm. The following measurements were made: Diameter of branch. Distance from tip. Width of cortex. Width of chlorophyll band. Depth of chlorophyll band. mm. 1-5 2 3-5 cm. 5 20 30 40 240 249 41S V- 32. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these i
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectplants, bookyear1908
