. The anatomy of woody plants. Botany -- Anatomy. FIBROVASCULAR TISSUES: PARENCHYMA 55 polished end of the trunk of an oak. The wood is clearly separated into two regions, a darker central and a pale peripheral. The deeply colored central region of the trunk constitutes the heartwood or duramen. The uncolored zone which surrounds this is the sapwood or alburnum. The dark-hued heartwood is extremely resistant to decay and constitutes the only material properly utilizable for exposed structures. In the case of dicotyledonous trees in general, one frequently notes even with the naked eye a differ
. The anatomy of woody plants. Botany -- Anatomy. FIBROVASCULAR TISSUES: PARENCHYMA 55 polished end of the trunk of an oak. The wood is clearly separated into two regions, a darker central and a pale peripheral. The deeply colored central region of the trunk constitutes the heartwood or duramen. The uncolored zone which surrounds this is the sapwood or alburnum. The dark-hued heartwood is extremely resistant to decay and constitutes the only material properly utilizable for exposed structures. In the case of dicotyledonous trees in general, one frequently notes even with the naked eye a difference in color between the heartwood and the sapwood. Sometimes this impor- tant distinction is not revealed to the eye, but becomes obvious only under microscopic investigation. Fre- quently the sap indi- cates its boundaries in the felled trunk by the discoloration brought about in its tissues either by oxidases or by fungi, or by both agencies united. In conifers, likewise, a distinction between a darker central heartwood and a surrounding pale-hued sapwood can be often recognized by the naked eye. The redwood or red cedar presents the contrast in color in a very marked manner. The larch and the spruce, which in the microscopic organization of their woods are practically identical, can be readily distinguished from one another by the gross aspect of their trunks. The larch has a dark-brown heartwood, while in the species of spruce the central region of the woody cylinder is in no way contrasted in color with the peripheral sapwood. It will be convenient in connection with the discussion of the parenchymatous or storage elements of the wood to elucidate certain features of the microscopic organization of the heartwood. FIG. 41.—Transverse view of an oak log showing heart- and 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
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