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2 Leaf blades 10-30 cm long; lower leaf surfaces pubescent across the surface (and often also with denser tufts of hairs in the vein axils). | |
5 Leaves small, thinner, glabrate or grayish-pubescent beneath, with conspicuous tufts of yellowish tomentum in the axils of the principal veins beneath; buds small, 3-5 mm long, ovate-lanceolate, grayish-pubescent; cups 10-15 mm wide, rounded or flattened at the base, with small grayish brown or red-brown scales closely appressed in a thin edge, covering less than one-third of the acorns; acorns 15-18 mm long, glabrous, or nearly so, sometimes faintly striated | |
5 Leaves usually large, thick, leathery, usually rusty-tomentose on the under surface, less conspicuously tufted with tomentum in the axils of the three primary veins beneath; buds large, 6-8 mm long, ovoid, or oval, prominently angled, covered with rusty-brown hairs; cups 10-20 mm wide, mostly turbinate or hemispheric, decidedly tapering at the base, the scales at the thick edge squarrose or loosely imbricate, cinnamon-red; acorns oblong, usually broader below than above, about 18 mm long, light yellow-brown, often striate, the shell usually lined with dense fulvous tomentum, enclosed for one-third to nearly two-thirds their length in the cups | |
4 Petioles long and slender, (14-) 20-50 mm long; lower leaf surfaces densely puberulent with tawny stellate hairs whose structure is barely visible at 10× magnification | |
7 Leaves 5-10 (-12) cm long, 5-lobed; shrub or small tree; [w. NC northward]; [section Lobatae; subsection Phellos] | |
7 Leaves (8-) 10-20 cm long, 5-12-lobed; small to large trees[collectively widespread in our area]. | |
8 Petioles 0.5-1.0 (-1.8) cm long, generally twisted such that the blade is oriented in a vertical plane; leaves all deeply lobed, some of the sinuses extending > 4/5 of the way to the midrib; pubescence of the lower leaf surface greenish yellow, matted, and glandlike, usually sloughing off by late in the year; [section Lobatae; subsection Phellos] | |
8 Petioles 2-5 cm long, not twisted so that the blade is oriented in a vertical plane; leaves shallowly to deeply lobed, some of the leaves on a tree generally shallowly lobed, none of the sinuses extending > 2/3 of the way to the midrib; pubescence of the lower leaf surface tawny or gray, stellate, not glandlike, persistent or sloughing off by late in the year. | |
9 Acorns 12-20 mm long, in a cup 15-25 mm across and 10-12 mm deep; mature leaves loosely and rather coarsely pubescent (the stellate hairs conspicuous and readily distinguishable at 10× magnification), often becoming nearly or entirely glabrous by late in the year (except for tufts of hairs in the vein axils); terminal bud 4-angled, 7-10 mm long, densely gray-tomentose; [section Lobatae; subsection Coccineae] | |
9 Acorns 10-15 mm long, in a cup 12-14 mm across and 4-5 mm deep; mature leaves densely and finely pubescent (the stellate hairs minute and scarcely distinguishable at 10× magnification), the pubescence permanent; terminal bud only obscurely angled (if at all), 5-8 mm long, brown-puberulent; [section Lobatae; subsection Phellos]. | |
10 Base of blades of sun-leaves typically rounded, thus forming a U-shape (some leaves cuneate, angled, or oblique); terminal lobe of leaves generally long-attenuated, narrow (its sides nearly parallel for much of its length), and curved to one side (falcate) (note that trees with the trilobed leaf form will key out above); leaves with 3-7 well-developed lobes, these often very irregular in size, shape, spacing, and orientation; pubescence of lower leaf surface normally tawny (when fresh) | |
10 Base of blades of sun-leaves typically cuneate or angled, thus forming a V-shape (some leaves somewhat U-shaped or oblique); terminal lobe of leaves generally short, broadly triangular (its sides normally tapering toward the tip for most of their length), not strongly curved to one side; leaves with 5-11 well-developed lobes, these generally rather uniform in size, shape, spacing, and orientation; pubescence of leaf surface gray | |
6 Mature leaves glabrous beneath on the surface, with tufts of hairs in the main vein axils beneath. | |
12 Terminal buds 4-angled, 7-10 mm long, the bud scales densely gray-tomentose; [section Lobatae; subsection Coccineae] | |
13 Leaves relatively shallowly lobed, the sinuses extending up to 2/3 of the way to the midrib; upper leaf surface dull, not lustrous; [section Lobatae; subsection Coccineae]. | |
13 Leaves relatively deeply lobed, the sinuses extending 2/3 to 9/10 of the way to the midrib; upper leaf surface lustrous. | |
16 Terminal bud moderately to strongly silver or reddish pubescent in its upper half; [section Lobatae; subsection Coccineae]. | |
20 Leaf blades mostly as wide or wider than long, 5 (-7)-lobed; [of dry glades and ridgetops]; [section Lobatae; subsection Coccineae] | |
20 Leaf blades mostly longer than wide, 5-7 (-11)-lobed; [of submesic or moist slopes and bottomlands]. | |