Fig. 4.—Portion of the cross-section
of a young root of Sanguinaria, showing the central radial bundle before any important secondary changes have occurred. The root-bundles are usually triarch or tetrarch, but in older roots the number of rays is much obscured by secondary formations so that the number of rays is difficult to determine.
a, a secretion-cell;
b, cell of endodermis;
c, small duct at end of xylem-ray;
d, pericambium layer, the cells of which contain much fine-grained starch;
e phloem mass, in which occur some secretion-cells. Magnification, about 112 diameters.
This image is from Some further observations on the structure of Sanguinaria canadensis in the American Journal of Pharmacy, 1895.