. The anatomy of woody plants. Botany -- Anatomy. THE ROOT 153 the secondary roots definitely take their origin from the same clusters of protoxylem which are subtended by aggregate rays in the secondary wood, it follows that the secondary roots are corre- lated with aggregate rays precisely as the traces of the leaf are imbedded in similar modifications of the radial parenchyma in the case of the stem. Aggregate rays are much more commonly found in the root than they are in the shoot organs, a consequence of the conserv- atism of the root, which is to be emphasized in a later chapter. The int
. The anatomy of woody plants. Botany -- Anatomy. THE ROOT 153 the secondary roots definitely take their origin from the same clusters of protoxylem which are subtended by aggregate rays in the secondary wood, it follows that the secondary roots are corre- lated with aggregate rays precisely as the traces of the leaf are imbedded in similar modifications of the radial parenchyma in the case of the stem. Aggregate rays are much more commonly found in the root than they are in the shoot organs, a consequence of the conserv- atism of the root, which is to be emphasized in a later chapter. The intimacy of the re- lation between the aggregate ray and the trace of the secondary root can be readily inferred from the ins'pec- tion of Fig. 109, a photograph of a transverse section of the root of Alnus japonica. It is clear that the trace is related to a mass of enlarged rays among which vessels are conspicuous by their absence, precisely as in the leaf trace illustrated in Fig. 130, page 177. It thus becomes clear that aggregate rays may be a feature of organization of the root as they are of the stem, and that in both organs the clusters or congeries of rays are most conspicuously developed in relation to the appendages. The secondary structures of the root are characterized by the same three types of multiseriate rays found in the wood of the stem as figured and diagrammed in chapter vi. In the case of the root, however, the primitive aggregate condition which pre- cedes both the compound and diffuse types tends strongly to FIG. 109.—Transverse section of part of same, more highly magnified. Description of this and last figure in 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 resemble the original Jeffrey, Edward C. (Edward Charles), b. 1866. Chicago, Ill. , The University of Chicago Press
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