454 CUPULIFER^E. (OAK FAMILY.) 



full-grown trees, bright green, shining above, turning red in autumn, deeply 

 pinnatifid, the lobes divergent and sparingly cut-toothed; acorns 6" -9" long, 

 the kernel and the scar in the cup whitish or yellowish ; bark of the trunk gray, 

 the interior reddish. — Moist or dry soil : common. 



Var. tinctdria. (Quercitron, Yellow-barked, or Black Oak. (Q. 

 tinctoria, Bartram.) Leaves, especially on young trees, often less deeply pinnat- 

 ifid, sometimes barely sinuate, more membranaceous, commonly retaining some 

 pubescence on the lower surface, turning brownish, orange, or dull red in au- 

 tumn ; bark of trunk darker-colored and rougher on the surface, thicker, and 

 internally orange, much more valuable for the tanner and dyer; cup sometimes 

 less top-shaped, rather hemispherical with a conical base, the scar inside orange- 

 colored, the kernel yellowish. But the shape of the acorn-cup and the charac- 

 ter of the bark do not always coincide : and in the figure of the younger Mi- 

 chaux, and in one of the two by the elder, the cup is just that of true coccinea. 

 The foliage, in general, approaches that of Q. rubra. — Rich and poor soil. 



Var. ambigua. (Gray Oak.) (Q. ambigua, or borealis, Michx. f.) 

 Found along our northeastern borders to Lake Champlain and northward, fig- 

 ured and briefly characterized as with the foliage of Q. rubra and the fruit of 

 Q. coccinea. The acorn in rising more out of the cup, also approaches the 

 former. The Oak of Lake Superior, with "wood better than that of Q. rubra" 

 (Dr. Robbins) has cup and acorn still more like this last. 



A hybrid Q. coccinea-ilicifolia is found by Dr. Robbins at Northbridge, 

 S. Massachusetts. 



15. Q,. rubra, L. (Red Oak.) Cup saucer-shaped or flat, with a narrow 

 raised border (9"- 12" in diameter), of rather fine closely appressed scales, sessile 

 or on a very short and abrupt narrow stalk or neck, very much shorter than the 

 oblong-ovoid or ellipsoidal acorn, which is 1 ' or less in length ; leaves rather thin, 

 moderately (rarely very deeply) pinnatifid, turning dark red after frost; bark 

 of trunk dark gray, smoothish. — Common both in rich and poor soil. — Tim- 

 ber coarse and poor. In Illinois and southward occurs a form with a deeper cup, 

 more or less conical at base. 



Var. runcinata, Engelm. Leaves with less deep and more ascending 

 lobes; fruit nearly half smaller; acorn 7" -9" long by 6" broad; cup with a 

 convex or obscurely top-shaped base : approaches the next therefore in fruit, 

 but not in foliage. St. Louis, in company with Q. rubra, palustris and imbri- 

 caria ; probably a hybrid. 



16. Q. palustris, Du Roi. (Swamp Spanish, or Pin Oak.) Cup flat- 

 saucer-shaped, sometimes contracted into a short scaly base or stalk ; fine-scaled 

 (5"-7"broad), very much shorter than the ovoid-globose acorn, which is 5"-7" 

 long ; leaves deeply pinnatifid with divergent lobes and broad rounded sinuses. 

 — Low grounds : rather common. — A middle-sized tree : timber accounted 

 better than of the last. 



2. CASTANEA, Tourn. Chestnut. 



Sterile flowers interruptedly clustered in long and naked cylindrical catkins : 

 calyx mostly 6-parted : stamens 8 - 20 : filaments slender : anthers 2-celled. 



