. A textbook of botany for colleges and universities ... Botany. Fig. 763. — A cross section of a submersed hydrophytic leaf, that of a pondweed {Potamogelon lucens), show- ing the few cell layers (here three) characteristic of a water leaf; note the abundance of chloroplasts (c) in the epidermis (e) and the absence of cutin- ized epidermal walls; highly magni- allel to the leaf surface. In submersed hydrophytes epidermal chloro- phyll usually is abundant (fig. 1018), often exceeding in amount that contained in the mesophyll, which may be loose and spongy by reason of the large air spac
. A textbook of botany for colleges and universities ... Botany. Fig. 763. — A cross section of a submersed hydrophytic leaf, that of a pondweed {Potamogelon lucens), show- ing the few cell layers (here three) characteristic of a water leaf; note the abundance of chloroplasts (c) in the epidermis (e) and the absence of cutin- ized epidermal walls; highly magni- allel to the leaf surface. In submersed hydrophytes epidermal chloro- phyll usually is abundant (fig. 1018), often exceeding in amount that contained in the mesophyll, which may be loose and spongy by reason of the large air spaces, or which may be reduced to a single layer (fig. 763). Hydrophytes with emersed leaves are much like mesophytes, except for their large lacunae (fig. 805). Shade plants are weak in palisade tissue, but, except in ferns (fig. 754), they rarely contain epidermal chlorophyll. In some leaves, especially in shade plants (such as Maranta and Asarum), the convex outer walls of the epidermal cells converge the rays of inci- wild ginger (Asarum cam- dent light; the reflection of some of these rays f"*^^', showing three epi- *^ dermal cells with convex gives a velvety aspect to the leaf (fig. 764). outer walls which converge Occasionally (as in Fittonia) isolated epidermal the rays of incident light; cells, known as ocellce, are more papillate than considerably magnified. are their neighbors. It has been supposed on somewhat uncertain evidence that epidermal cells with convex outer walls are organs of light perception. A more probable role of such cells is the facilita- tion of synthesis through light convergence. In the luminous moss, Schistostega, the chloroplasts are near the base of a globose cell, which, ?IG. 764. — A cross section of the upper part of a shade leaf, that of the. 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 res
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910
