Veratrum Viride From Cypripedium. Veratrum viride has one-seventh diameter in cortex consisting of parenchyma having starch, sometimes calcium oxalate, few wood-bundles, one-eighth inch from outside has brownish wavy nucleus-sheath, centre with many wood-bundles; cypripedium has thick cortex, indistinct nucleus-sheath, wood-bundles approximate, more distinct centrally, parenchyma has starch. See pages 98, 139.
Arnica From Strawberry. Arnica has thick bark, thin cork, circle of resin-cells, wood-wedges in a close circle enclosing large pith; strawberry rhizome has no resin-cells, but contains starch. See page 612.
Serpentaria From Spigelia. Serpentaria has thin bark containing some oil-cells, wood-wedges longest on under side, separated by broad medullary rays, pith large-celled; spigelia has thin bark, divided into two distinct layers, an inner third and outer two-thirds; wood-circle thickest on under side, radiate, continuous except usually at one end where wood is missing, medullary rays hardly visible. Pith oval and sometimes decayed; resin-spots in wood, especially around pith. See pages 169, 469.
Hydrastis From Caulophyllum. Hydrastis has thick bark, broad wood-wedges, not fixed in number (often 10), decidedly yellow; medullary rays broad, yellow, pith large, both, like the bark, contain starch; caulophyllum has thin bark, wood-wedges not so long as in hydrastis, medullary rays broad, pith large, parenchyma contains starch. See pages 188, 210.
Helleborus Niger From Helleborus Viridis. Helleborus niger has bark thick, circle of 8 wood-wedges, broad medullary rays, pith large; helleborus viridis has circle of 4 wood-wedges, broad medullary rays. See pages 193, 194.