Anatomy of Certain Goldenrods
In dealing with the anatomical features of Solidago, and especially in studying the modifications of its woody cylinder in relation to the leaf trace, it is well to bear in mind the fact that the goldenrods belong to a family which occupies a high place systematically. The largest proportion of herbs and short-lived perennials, especially in temperate regions, belongs to the Compositae; and since they are so generally admitted to be high forms, a certain amount of evolutionary progress can be
... y progress can be taken for granted in studying them. Another advantage in investigating genera of the Compositae is the fact that in the family and in any genus of the family both the woody and herbaceous type of stem may be found; hence comparisons are more easily made and conclusions more readily drawn. Not only within the same genus are both kinds of stem to be found, but the same aerial axis has regions which are characteristically woody and herbaceous. This situation is well illustrated by Solidago. In the lower portions of the aerial axis, as well as in the subterranean parts of the stem, the organization is typically woody; while in the higher and more slender portions of the stem the herbaceous type prevails. In short, Solidago presents an epitome of a woody-herbaceous condition in which the transition from one type to the other is advantageously elucidated. The species of goldenrod studied were Solidago canadensis, S. bicolor, S. rigida, S. caesia, S. speciosa, S. sempervirens, S. graminifolia, S. latifolia, S. serotina, and S. patula. It was found that in all these species there are certain modifications of the woody cylinder related definitely to the leaf strands. These consist in the transformation of portions of the woody segment through which the leaf trace takes its departure into parenchyma and in the elimination of fibers and vessels.