2. Pith rays very broad and conspicuous .......................OAK. D. Pores of summer wood mostly but little smaller than those of the spring wood, isolated and scattered; very heavy and hard woods. The pores of the spring wood sometimes form but an imperfect zone. (Some diffuse-porous woods of groups A and B may seem to belong here.) 1. Fine concentric lines (not of pores) as distinct, or nearly so, as the very fine pith rays; outer summer wood with a tinge of red; heart-wood light reddish brown ....................HICKORY. 2. Fine concentric lines, much finer than the pith rays; no reddish tinge in summer wood; sap-wood white; heart-wood blackish .............................................PERSIMMON. ==== ADDITIONAL NOTES FOR DISTINCTIONS IN THE GROUP. Sassafras and mulberry may be confounded but for the greater weight and hardness and the absence of odor in the mulberry; the radial section of mulberry also shows the pith rays conspicuously. Honey locust, coffee tree, and black locust are also very similar in appearance. The honey locust stands out by the conspicuousness of the pith rays, especially on radial sections, on account of their height, while the black locust is distinguished by the extremely great weight and hardness, together with its darker brown color. [Illustration: Fig. 131. Wood of Coffee Tree.] The ashes, elms, hickories, and oaks may, on casual observation, appear to resemble one another on account of the pronounced zone of porous spring wood. (Figs. 129, 132, 135.) The sharply defined large pith rays of the oak exclude these at once; the wavy lines of pores in the summer wood, appearing as conspicuous finely-feathered hatchings on tangential section, distinguish the elms; while the ashes differ from the hickory by the very conspicuously defined zone of spring wood pores, which in hickory appear more or less interrupted. The reddish hue of the hickory and the more or less brown hue of the ash may also aid in ready recognition. The smooth, radial surface of split hickory will readily separate it from the rest. [Illustration: Fig. 132. _A_, black ash; _B_, white ash; _C_, green ash.] The different species of ash may be identified as follows (Fig. 132): 1. Pores in the summer wood more or less united into lines. _a._ The lines short and broken, occurring mostly near the limit of the ring .......................................WHITE ASH. _b._ The lines quite long and conspicuous in most parts of the summer wood .......................................GREEN ASH. 2. Pores in the summer wood not united into lines, or rarely so. _a._ Heart-wood reddish brown and very firm ..............RED ASH. _b._ Heart-wood grayish brown, and much more porous ....BLACK ASH.