Flora of the Southeastern United States
2022 Edition

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Key to Quercus, Key A: Leaves (most of them) entire and unlobed (Laurel Oaks and Live Oaks)

1 Leaves broadly obovate or spatulate, 1-2.5 (-3)× as long as wide.
..2 Leaves 10-30 cm long, with rounded, subcordate, truncate, or oblique bases; lower leaf surfaces thinly to densely pubescent with tawny to orange glandlike hairs; [section Lobatae; subsection Phellos]
....3 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
....3 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
..2 Leaves 2-10 (-15) cm long, mostly with cuneate or rounded bases (in some species sometimes subcordate, truncate, or oblique); lower leaf surfaces glabrous, glabrescent, or pubescent, but the pubescence not orange and glandlike.
......4 Leaves shallowly and regularly serrate; leaves densely white pubescent beneath; [alien species, rarely planted and persistent; [section Cerris; "West Asia group"]
......4 Leaves entire or with few and irregular teeth; leaves variously glabrous to pubescent beneath; [native species].
........5 Twigs of the current year densely and finely hairy, obscuring the surface; [scrubby trees of sandhills from se. SC southward to FL, west to s. AL]; [section Quercus; subsection Stellatae]
........5 Twigs of the year glabrous or sparsely pubescent; [shrubs, scrubby small trees, or large trees of various habitats, and collectively widespread in our area].
..........6 Leaves grayish beneath; [section Quercus; subsection Stellatae]
............ 7 Shrubs or small trees to 3(–5) m tall, often forming thickets, trunks multiple from near ground; acorn 7-12 (-15) mm long, 7-10 mm in diameter; [of dry limestone hills of OK and TX]
............ 7 Trees to 20 m tall, trunk usually solitary; acorn 12-15 (-18) mm long, 8-12 (-17) mm in diameter; [of moist bottomlands, riparian habitats and calcareous bluffs of SC west to TX]
..........6 Leaves bright green or orange-scurfy beneath; [section Lobatae; subsection Phellos].
............ ..8 Leaf blade strongly convex; lower leaf surface orange-scurfy; [of sandhills and scrub from n. FL southward]
............ ..8 Leaf blade planar (the margins sometimes revolute); lower leaf surface glabrous or pubescent and also with tufts of hairs in the vein axils; [collectively more widespread in habitat and distribution].
............ ....9 Leaves evergreen, (including the petiole) usually < 4 cm long (sometimes to 9 cm long) and < 2 cm wide (to 6 cm wide); lower leaf surface usually entirely glabrous at maturity (rarely with pubescence in the vein axils); leaf blades rarely lobed; [shrub to scrubby tree of sandhills in se. SC and southward]
............ ....9 Leaves deciduous, (including the petiole) usually > 5.5 cm long (rarely smaller) and usually 3-5 cm wide; lower leaf surface usually with tufts of hairs in the main vein axils beneath; leaf blades often lobed.
............ ......10 Leaves with broadly cuneate to rounded leaf bases, the blades 5-15 cm long; lower leaf surfaces generally pubescent across the surface, and also with tufts in the axils; [of sw. GA westward]
............ ......10 Leaves with cuneate bases, the blades 5-10 (-15) cm long; lower leaf surfaces glabrous, except for tufts of hairs in the vein axils; [widespread in our area]
1 Leaves linear, elliptic, or narrowly obovate, 2-10× as long as wide.
............ ........11 Leaves (at maturity) glabrous or at most sparsely pubescent on the surface below, though often with tufts of hairs in the main vein axils.
............ ..........12 Twigs of the year densely and finely hairy, obscuring the surface; leaves (at maturity) sparsely pubescent beneath; [scrubby trees of sandhills from se. SC south to FL, west to s. AL]; [section Quercus; subsection Stellatae]
............ ..........12 Twigs of the year glabrous or sparsely pubescent; leaves (at maturity) bright green and glabrous beneath, though often with tufts of hairs in the main vein axils; [medium to large trees, more widespread, mostly of moist habitats, except Q. hemisphaerica]; [section Lobatae; section Phellos].
............ ............ 13 Leaves predominantly lanceolate, mostly 6-12 cm long and 0.7-2 cm wide, most of them 5-8× as long as wide, the apex acute; mature leaves with tufts of hairs in the vein axils below, and sometimes also some pubescence on the blade surface near the midrib; blades never with lobes or teeth; leaves deciduous in autumn; young leaves bronze red, emerging tightly rolled lengthwise and appearing linear; [trees of bottomlands and upland depression swamps, mesic uplands, and also weedy and frequent in disturbed successional habitats]
............ ............ 13 Leaves predominantly oblanceolate, obovate, or rhombic, mostly 2.5-10 cm long and 1.5-4 cm wide, most of them 2-5× as long as wide, the apex acute, obtuse, or rounded; mature leaves with or without tufts of hairs in the vein axils below, lacking pubescence on the blade surface; blades sometimes with 1-5 lateral lobes or teeth; leaves persisting until spring, or tardily and irregularly deciduous in winter; young leaves red, yellow, or green, not emerging tightly rolled lengthwise; [trees primarily either of swamp forests, maritime forests, or sandhills, not typically weedy].
............ ............ ..14 Mature leaves entirely glabrous below; leaves mostly with acute apices and bristle tips (rarely a few rounded), mostly 2.5-8 cm long and 1-2 (-3) cm wide, the upper surface shiny, the vein network not readily visible when backlit; leaves evergreen (persisting until spring); petiole 0.5-2 mm long; leaves of vigorous growth often with dentate lobes; [trees of dry sandy habitats, such as sandhills, maritime forests, and dry hammocks]
............ ............ ..14 Mature leaves with tufts of stellate trichomes in the vein axils; leaves mostly with rounded apices (rarely a few acute and then bristle-tipped), mostly 5-10 cm long and (1.8-) 2-4 cm wide, the upper surface dull, the vein network readily visible when backlit; leaves tardily deciduous (at least northwards in the Southeast); petiole 2-6 mm long; leaves of vigorous growth rarely lobed, and then not dentate; [trees of moist habitats, such as floodplain forests, mesic slopes, and moist hammocks]
............ ........11 Leaves (at maturity) persistently and densely pubescent on the surface below, the pubescence in some species so dense and tight as to be difficult to perceive without at least 10× magnification.
............ ............ ....15 Leaves bristle-tipped (sometimes the bristle fallen or broken off, but leaving a truncate scar), deciduous in autumn; multi-armed trichomes of the rosulate or multiradiate types, many of the arms ascending or erect (never with the stellate or fused-stellate trichomes characteristic of the live oaks); acorns maturing in 2 years (immature acorns present through the winter on fruiting trees); [section Lobatae; subsection Phellos].
............ ............ ......16 Leaves (including petiole) mostly 10-17 cm long, 3.5-7 cm wide; lower leaf surface (at maturity) sparsely to moderately densely pubescent with soft hairs; leaves lustrous dark-green above; [trees of the Mountains, Piedmont, and rarely Coastal Plain]
............ ............ ......16 Leaves (including petiole) mostly 4-11 cm long, 0.5-3.0 cm wide; lower leaf surface densely covered with soft hairs; leaves lustrous dark-green or bluish-green above; [stoloniferous shrubs and small to medium trees of the Coastal Plain].
............ ............ ........17 Leaves 0.5-1.5 cm wide, mostly 4-8× as long as wide, lustrous dark-green above; acorns 8-12 mm long; petioles 1-3 mm long; [plant a stoloniferous shrub, to 1 m tall (or to 2 m in fire-suppressed pinelands)]
............ ............ ........17 Leaves 1.5-3.0 cm wide, mostly 2-4× as long as wide, dull bluish-green above; acorns 10-15 mm long; petioles 4-15 mm long; [plant a small to medium tree]
............ ............ ....15 Leaves not bristle-tipped, evergreen (overwintering, falling with the expansion of new leaves in the spring) or deciduous (in Q. oglethorpensis and Q. mohriana); multi-armed trichomes of the fused-stellate and stellate types, the arms parallel to the leaf surface, radiating from a well developed disc that appears as a white eye or dot at 20-40× magnification (or rosulate or multiradiate in Q. oglethorpensis and Q. mohriana); acorns maturing in 1 year (immature acorns not present through the winter, unless aborted).
............ ............ ..........18 Stellate hairs of the leaf undersurfaces at least in part erect or semi-erect, sometimes also with appressed stellae; leaves either deciduous in autumn or evergreen to tardily deciduous; bark gray.
............ ............ ............ 19 Stellate hairs of the leaf undersurfaces with (4-) 6+ rays; bark dark gray, deeply furrowed; [trees of the rocky limestone hills, c. OK and c. TX]; [section Quercus; subsection Polymorphae]
............ ............ ............ 19 Stellate hairs of the leaf undersurfaces with 1-4 rays; bark light gray, resembling that of Quercus alba; [bottomlands and upland clay flats, GA and SC]; [section Quercus; subsection Stellatae]
............ ............ ..........18 Stellate hairs of the leaf undersurfaces appressed to the surface; leaves evergreen (overwintering, falling with the expansion of new leaves in the spring); bark (on the tree species) brownish, deeply furrowed; [trees and stoloniferous shrubs either of sandy habitats of the Coastal Plain of GA, NC, SC, and VA or of rocky limestone areas of c. OK and c. TX]; [section Virentes].
............ ............ ............ ..20 Plant a stoloniferous shrub, to 1 m tall (or to 2 m in fire-suppressed pinelands) and producing acorns at that size
............ ............ ............ ..20 Plant a small to large tree, not producing acorns until >2m tall.
............ ............ ............ ....21 Leaf blades with the margins strongly revolute, and also the sides of the blades generally rolled downward and obscuring part of the lower surface, the leaf appearing boatlike (the depth of the "boat" often approaching the width of the leaf); midvein and major lateral veins impressed on the upper surface and raised on the lower surface (the lower surface therefore appearing rugose); buds dark brown; cup scales gray-tipped; pubescence of the lower surface stellate, both appressed and erect, the individual stellae readily visible at 20× magnification (sometimes at 10× magnification); acorns (1-) 2 (-6) per stalk; [typically a small tree of dry sands]
............ ............ ............ ....21 Leaf blades flat, or the margins slightly to strongly revolute, the sides of the blade sometimes rolled downward, usually not obscuring part of the lower surface, the leaf not boatlike (the leaf much wider than deep); midvein and major lateral veins not impressed (or very slightly so) on the upper surface and only very slightly, if at all, raised on the lower surface (the lower surface therefore not appearing notably rugose); buds red-brown; cup scales red-tipped; pubescence of the lower surface stellate, all of it tightly appressed, the individual stellae readily visible only at 30× magnification (sometimes barely distinguishable at 20× magnification); acorns 1-2 per stalk.
............ ............ ............ ......22 Nut (17-) 20-30 (-33) mm, apex acute; [of OK and c. and s. TX, mainly dry habitats of limestone, gravels, and sands]
............ ............ ............ ......22 Nut 15-20 (-25) mm, apex rounded or blunt; [of e. TX eastwards, typically a large upland or bottomland tree, or northwards a salt-pruned shrub to large tree of dunes and estuarine shorelines]]

Key to Quercus, Key D: Leaves with lobes or teeth bristle-tipped (Red Oaks)

1 Leaves shallowly 3-lobed near the broad apex (some leaves of sprout or juvenile shoots may be more lobed); [section Lobatae; subsection Phellos].
..2 Leaf blades 5-15 cm long; lower leaf surfaces glabrous, except for tufts of hairs in the vein axils (or pubescent across the surface in Q. arkansana].
....3 Leaves with broadly cuneate to rounded leaf bases, the blades 5-15 cm long; lower leaf surfaces generally pubescent across the surface, and also with tufts in the axils; [of sw. GA westward]
....3 Leaves with cuneate bases, the blades 5-10 (-15) cm long; lower leaf surfaces glabrous, except for tufts of hairs in the vein axils; [widespread in our area]
..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).
......4 Petioles short and stout, 5-15 mm long; lower leaf surfaces thinly to densely pubescent with a mixture of tawny or orange glandlike hairs and stellate hairs whose structure is easily visible at 10× magnification
........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
1 Leaves shallowly to deeply 5-12-lobed (some of the leaves of Q. georgiana only 3-lobed), the lobes primarily lateral.
..........6 Mature leaves pubescent beneath on the surface with stellate hairs.
............ 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 5-9 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.
............ ........11 Petioles 0.5-1.0 (-1.8) cm long, generally twisted such that the blade is oriented in a vertical plane; inner cup-scales of the acorn cup inflexed, thus the cup appearing to have a broadly rounded rim; [section Lobatae; subsection Phellos]
............ ........11 Petioles 2.0-7 cm long, not twisted so that the blade is oriented in a vertical plane; inner cup-scales of the acorn cup not inflexed, thus the cup appearing to have a sharp rim appressed against the acorn.
............ ..........12 Terminal buds 4-angled, 7-10 mm long, the bud scales densely gray-tomentose; [section Lobatae; subsection Coccineae]
............ ..........12 Terminal buds not 4-angled, 3-5 (-7) mm long, the bud scales glabrous or with ciliate margins.
............ ............ 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].
............ ............ ..14 Acorn cup covering about 1/4 of acorn; leaf sinuses extending about ¼ of the way to the midrib; bark of mature trees dark gray to black; [widespread in our area, at low to medium elevations]
............ ............ ..14 Acorn cup covering about 1/3 of acorn; leaf sinuses extending about 1/3 of the way to the midrib; bark of mature trees medium gray; [of the Mountains, mostly at 1000 m and above]
............ ............ 13 Leaves relatively deeply lobed, the sinuses extending 2/3 to 9/10 of the way to the midrib; upper leaf surface lustrous.
............ ............ ....15 Larger lateral lobes of most leaves with 1 bristle per lobe (-2 on some lobes); total bristle tips < 10/leaf; [section Lobatae; subsection Phellos]
............ ............ ....15 Larger lateral lobes of most leaves with 2 or more bristles; total bristle tips 9-50/leaf.
............ ............ ......16 Terminal bud moderately to strongly silver or reddish pubescent in its upper half; [section Lobatae; subsection Coccineae].
............ ............ ........17 Cup turbinate to hemispheric, scales with broad glossy base, scale margins often strongly concave; nut ovoid to subglobose, with 1 or more concentric rings of pits at apex; [of ME and WI south to s. GA, s. AL, e. LA, AR and MO]
............ ............ ........17 Cup deeply cup-shaped to turbinate, scales pubescent with straight or slightly concave margins; nut ellipsoid to ovoid, without rings of pits at apex; [of n. OH west to e. ND, south to c. IL and MO]
............ ............ ......16 Terminal bud glabrous or with a few scattered hairs.
............ ............ ..........18 Lower surface of mature leaf blade glabrous or with minute tufts of hairs in the vein axils; acorn scar 3.5-8 mm in diameter; [of e. and c. OK south to sc. TX]; [section Lobatae; subsection Coccineae].
............ ............ ..........18 Lower surface of mature leaf blade with conspicuous tufts of hairs in the vein axils; acorn scar 5-13 mm in diameter; [collectively widespread].
............ ............ ............ 19 Primary leaf lobes (and the secondary veins leading to them) largely alternate; acorn cup with thin (< 1.5 mm in cross section) walls, deeply goblet-shaped, covering 1/3-1/2 of the nut, the inner surface pubescent; [section Lobatae; subsection Palustres]
............ ............ ............ 19 Primary leaf lobes (and the secondary veins leading to them) opposite or sub-opposite; acorn cup with thick (> 1.5 mm in cross section) walls, saucer- or cup-shaped, covering 1/4-1/3 of the nut, inner surface glabrous or with ring of hairs around scar.
............ ............ ............ ..20 Leaf blades mostly as wide or wider than long, 5 (-7)-lobed; [of dry glades and ridgetops]; [section Lobatae; subsection Coccineae]
............ ............ ............ ....21 [AR only]
............ ............ ............ ....21 [fairly widespread in the inland provinces]
............ ............ ............ ..20 Leaf blades mostly longer than wide, 5-7 (-11)-lobed; [of submesic or moist slopes and bottomlands].
............ ............ ............ ......22 Nuts (8-) 10-14 (-16) mm long; mature leaf blades mostly 7-12 cm long, 5-11 cm wide (averaging about 9 cm long and 8 cm wide), with 5-7 lobes; [section Lobatae; subsection Palustres]
............ ............ ............ ......22 Nuts 14-30 mm long; mature leaf blades mostly (7.5-) 10-20 cm long, 6-15 cm wide (averaging about 13 cm long and 11 cm wide), with (5-) 7-9 (-11) lobes; [section Lobatae; subsection Coccineae]