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 C: Leaves with lobes not bristle-tipped (White Oaks)

1 Lower surfaces of mature leaves glabrous.
..2 Leaf lobes with acute apices; sinuses often both broad and "flat-bottomed" (with portions parallel to the midrib); acorn cup covering 2/3 to 3/4 of acorn; [section Quercus; subsection Prinoideae]
..2 Leaf lobes with obtuse apices; sinuses narrow (often notch-like), narrowly to broadly rounded or triangular (lacking portions parallel to the midrib); acorn cup covering < 1/4 to 1/2 of acorn.
....3 Leaves mostly 4-10 (-17) cm long, 2-5 (-9) cm wide, with 1-5 shallow lobes or undulations, extending 1/8 to 1/2 of the way to the midrib; acorn cup flat at the base, covering < ¼ of the acorn; [section Quercus; subsection Stellatae].
......4 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; [dry limestone hills of OK and TX]
......4 Trees to 20 m tall, trunk usually solitary; acorn 12-15 (-18) mm long, 8-12 (-17) mm in diameter; [moist bottomlands, riparian habitats and calcareous bluffs of SC west to TX]
....3 Leaves mostly 7-20 cm long, 3-10 cm wide, with 3-11 lobes, extending 1/4 to 5/6 of the way to the midrib (if the lobing < ½ of the way to the midrib, then the acorn cup rounded at the base and covering 1/4 to 1/2 of the acorn).
........5 Leaf base deeply cordate; [alien, sometimes planted and persistent]
........5 Leaf base cuneate; [native].
..........6 Leaves with 7-11 lobes (the sinuses usually deep, those of the larger leaves usually about 2/3 to 5/6 of the way to the midrib), 10-20 cm long, 5-10 cm wide; terminal bud rounded or globose; basal scales of acorn cup thickened, the thickening giving the cup a knobby texture; [section Quercus; subsection Albae]
..........6 Leaves with 3-7 lobes (the sinuses usually shallow, those of the larger leaves usually ranging from 1/4 to 1/2 of the way to the midrib), 7-15 cm long, 3-8 cm wide; basal scales of the acorn cup thin, appressed, the cup having a rough but not knobby texture; [section Quercus; subsection Stellatae]
1 Lower surfaces of mature leaves pubescent, the pubescence varying from dense to sparse (sometimes minute and requiring 10× magnification to be readily visible).
............ 7 Lower surfaces of mature leaves whitish to pale green, with a mixture of minute, sessile, stellate hairs with horizontal tips and longer stellate hairs with erect ascending tips; leaves shallowly lobed (if so, the lobes 9-19) to deeply lobed (if so, the lobes with acute apices), the sinuses extending 1/4 to 4/5 of the way to the midrib; [section Quercus; subsection Prinoideae].
............ ..8 Leaves mostly shallowly lobed at the base, the sinuses extending 1/4 to 1/2 of the way to midrib, grading into mere crenations toward the tip of the leaf, the total number of lobes/crenations usually 9-19; acorns borne on peduncles 2-10 cm long; acorn cup covering 1/3 to 1/2 of acorn, the upper scales with long-acuminate apices
............ ..8 Leaves mostly relatively deeply lobed throughout the length of the leaf, the sinuses extending 1/2 to 4/5 of the way to the midrib, the total number of lobes 3-13; acorns sessile or borne on peduncles up to 1 cm long; acorn cup covering 1/3 to 3/4 of acorn, the upper scales with acute, long-acuminate, to long-awned apices.
............ ....9 Upper scales of the acorn cups thin and acute; acorn cup covering ½ to 3/4 of the acorn; [swamps in the Coastal Plain and lower Piedmont of GA, NC, SC, and VA]
............ ....9 Upper scales of the acorn cups long-attenuate into nearly terete awns; acorn cup covering 1/3 to 1/2 of the acorn; [Mountains of VA]
............ 7 Lower surfaces of mature leaves gray, green, pale green, or yellowish, glabrescent or densely pubescent, the hairs few-branched and erect; leaves mostly relatively deeply and obtusely lobed, rarely shallowly lobed (if so, the lobes 3-7), the sinuses extending 1/2 to 4/5 of the way to the midrib, the total number of lobes 3-7; acorns sessile or nearly so.
............ ......10 Leaf lobes with acute apices; acorn cup covering 2/3 to 3/4 of acorn; [section Quercus; subsection Prinoideae]
............ ......10 Leaf lobes with obtuse to rounded apices; acorn cup covering 1/3 to 1/2 of acorn; [section Quercus; subsection Stellatae].
............ ........11 Woody twigs of the season glabrous or with scattered, deciduous 2-forked hairs; petioles of mature leaves 3-10 (-15) mm long; leaf blades (2.5-) 4-8 (-13.5) cm long, irregularly and often rather shallowly 3-5 (-7) lobed, the overall form of the leaf only rarely cruciform; largest lateral lobes usually at the midpoint of the blade (or even below it), the lobes usually not sublobed, tapering from base to tip; [xeric sandy sites in the Coastal Plain from se. VA southwards to c. peninsular and westwards to c. OK and c. TX]
............ ........11 Woody twigs of the season densely and persistently stellate-pubescent, especially toward the tip of the twig; petioles of mature leaves 15-20 mm long (Q. stellata) or 3-10 (-15) mm long (Q. boyntonii and Q. similis); leaf blades (5-) 7.5-15 (-20) cm long, usually 5-lobed, the overall form of the leaf typically cruciform (Q. stellata) or not (Q. boyntonii and Q. similis); largest lateral lobes of the leaves usually above the midpoint of the blade, these lobes either often sublobed or squarish in shape, usually wider near their tips than at their bases (Q. stellata) or not sublobed, tapering from base to tip (Q. boyntonii and Q. similis); [collectively widespread in our area].
............ ..........12 Leaves usually cruciform, the largest lateral lobes often sublobed or squarish in shape, usually wider near their tips than at their bases, and borne at right angles to the midrib; upper leaf blade surface glabrous; [usually of dry to dry-mesic upland situations, widespread in our area]
............ ..........12 Leaves not cruciform, the largest lateral lobes usually not sublobed, the lobes tapering from base to tip, and borne at ascending angles relative to the midrib; upper leaf blade surface at least sparsely stellate-puberulent (even late into the season); [of temporarily flooded calcareous swamps of the Coastal Plain, from SC (NC?) southward and westward (Q. similis) or localized on sandstone in nc. AL (Q. boyntonii)].
............ ............ 13 Rhizomatous shrubs to small trees, generally < 2 m tall; [sandstone outcrops in nc. AL]
............ ............ 13 Single-trunked large trees; [usually of temporarily flooded calcareous swamps of the Coastal Plain, from SC (NC?) southward and westward]