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Key to Ericaceae

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1 Plant an herb, subshrub, or sprawling shrub, not clonal by underground rhizomes (except Gaultheria procumbens and Epigaea repens), rarely > 3 dm tall; plants mycotrophic or hemi-mycotrophic (except Epigaea, Gaultheria, and Arctostaphylos).
..2 Plants without chlorophyll (fully mycotrophic); stems fleshy; leaves represented by bract-like scales, white or variously colored, but not green; pollen grains single; [subfamily Monotropoideae; tribe Monotropeae].
....3 Petals united; fruit nodding, a berry; flower and fruit several per stem
....3 Petals separate; fruit erect, a capsule; flower and fruit 1-several per stem.
......4 Flowers few to many, racemose; stem pubescent, at least in the inflorescence; plant yellow, orange, or red when fresh, aging or drying dark brown
......4 Flower solitary; stem glabrous; plant white (rarely pink) when fresh, aging or drying black
..2 Plants with chlorophyll (hemi-mycotrophic or autotrophic); stems woody; leaves present and well-developed, green; pollen grains in tetrads (single in Orthilia).
........5 Herb with a rosette of ascending basal leaves; flowers scapose; [subfamily Monotropoideae; tribe Pyroleae].
..........6 Style and filaments straight; filaments straight, the anthers closely surrounding the style; inflorescence distinctly secund (1-sided)
..........6 Style and filaments strongly declined; filaments curved, the anthers not closely surrounding the style; inflorescence slightly or not at all secund (1-sided)
........5 Subshrub or sprawling shrub with cauline leaves; flowers axillary (except scapose in Chimaphila).
............ 7 Plant erect, the leaves clustered near the apex of the single stem.
............ ..8 Leaves lanceolate or oblanceolate, normally 2-4× as long as wide (sometimes proportionately less narrow in stunted individuals; fruit a capsule, borne 1-several on an erect scape above the leaves [subfamily Monotropoideae; tribe Pyroleae]
............ ..8 Leaves obovate, 1-2× as long as wide; fruit a red berry, borne on nodding axillary pedicels beneath the leaves; [subfamily Vaccinioideae; tribe Gaultherieae]
............ 7 Plant creeping or sprawling, leaves scattered along the stems.
............ ....9 Flowers solitary and axillary; fruit a white berry; [subfamily Vaccinioideae; tribe Gaultherieae]
............ ....9 Flowers in axillary or terminal spikes or racemes; fruit a fleshy loculicidal capsule or red drupe.
............ ......10 Leaves glabrous, 1-3 cm long, tapered to the base; corolla urceolate; calyx not subtended by large bracts; [subfamily Arbutoideae]
............ ......10 Leaves pilose (glabrate in age), 2-10 cm long, rounded or subcordate at the base; corolla salverform, the lobes spreading; calyx subtended by 2 large bracts; [subfamily Ericoideae; tribe Phyllodoceae]
1 Plant either a shrub or tree (> 3 dm tall), or a shrub 1-3 dm tall (rarely a woody needle-leaved subshrub 0.5-1 m and definitely and obviously clonal by underground rhizomes; plants not mycotrophic or hemi-mycotrophic.
............ ........11 Leaves ca. 1 mm wide, 3-12 mm long, appearing opposite, alternate, or whorled (the internodes very short, thus the leaves generally appearing whorled); petals absent; fruit a subglobose, 2-stoned drupe, 1-3 mm in diameter; branches often appearing in whorls of 3-7; [subfamily Ericoideae; tribe Empetreae]
............ ..........12 Leaves 5-15 mm long; shrubs 5-25 dm tall; drupes red, 1.5-3 mm in diameter; [of SC southward]
............ ..........12 Leaves 3-6 mm long; shrubs 1.5-6 dm tall; drupes gray, 1-1.5 mm in diameter; [of NJ northward]
............ ........11 Leaves either > 2 mm wide or < 5 mm long, mostly alternate or whorled; petals present; fruit not as above, mostly either a capsule or 10- or many-seeded berry; branches appearing alternate or whorled; [subfamily Vaccinioideae; tribe Vaccinieae].
............ ............ 13 Ovary inferior; fruit indehiscent, a fleshy berry; [blueberries and huckleberries].
............ ............ ..14 Ovary 10 locular; seeds 10; leaves glandular-punctate, at least on the lower surface (except G. brachycera)
............ ............ ..14 Ovary 4-5 locular; seeds numerous; leaves not glandular-punctate
............ ............ 13 Ovary superior; fruit dehiscent, a dry capsule; [other heaths].
............ ............ ....15 Petals separate; fruit 2-7-locular; either a shrub to 1 m tall with ovate to oblong, evergreen leaves, 0.6-1.2 cm long, or a shrub to small tree 2-6 (-9) m tall with elliptic, deciduous leaves, 4-12 cm long, or a shrub 1-2.5 m tall, with elliptic to ovate, evergreen leaves 2-4 cm long; [subfamily Ericoideae; tribe Phyllodoceae]. {add Rhododendron groenlandicum}
............ ............ ......16 Fruit 2-3 (5)-locular; shrub to 1 m tall; leaves, 0.4-1.2 cm long; petals 2-4 mm long
............ ............ ......16 Fruit 4-7-locular; shrub to small tree 1-6 (-9) m tall; leaves 2-12 cm long; petals 12-30 mm long.
............ ............ ........17 Fruit 7-locular; leaves evergreen 2-4 cm long; petals 20-30 mm long; shrub 1-2.5 m tall
............ ............ ........17 Fruit 4-5-locular; leaves deciduous, 4-12 cm long; petals 12-14 mm long; shrub to small tree 2-6 (-9) m tall
............ ............ ....15 Petals fused for part or all their lengths; fruit (4-) 5-locular; shrub or tree with leaves of various shape, evergreen or deciduous, these either < 6 mm long, linear and whorled, or > 12 mm long.
............ ............ ..........18 Leaves opposite or whorled, < 5 mm long, linear; [subfamily Ericoideae, tribe Ericeae]
............ ............ ............ 19 Leaves opposite, sessile, clasping at the base
............ ............ ............ 19 Leaves whorled (in 4s), petiolate
............ ............ ..........18 Leaves alternate or whorled, > 20 mm long.
............ ............ ............ ..20 Flowers 4-merous; fruits 4-locular; leaves with a series of fascicles of trichomes on the midrib below; [subfamily Ericoideae; tribe Rhodoreae]
............ ............ ............ ..20 Flowers 5-merous; fruits 5-locular; leaves not as above.
............ ............ ............ ....21 Leaves coriaceous, evergreen, shiny and dark green above.
............ ............ ............ ......22 Leaves sharply and distinctly serrate.
............ ............ ............ ........23 Pedicels slender, 7-10 mm long; filaments strongly curved just below the anthers; pith transversely diaphragmed; [subfamily Vaccinioideae; tribe Lyonieae]
............ ............ ............ ........23 Pedicels stout, 2-6 mm long; filaments straight; pith solid; [subfamily Vaccinioideae; tribe Gaultherieae]
............ ............ ............ ......22 Leaves entire, or obscurely and finely crenulate-serrulate.
............ ............ ............ ..........24 Capsules elongate, > 2× as long as broad, 8-18 mm long; [subfamily Ericoideae; tribe Rhodoreae]
............ ............ ............ ..........24 Capsules ovoid to globose or subglobose, about as long as broad, 5-8 mm long.
............ ............ ............ ............ 25 Leaves with a prominent vein running parallel to (and about 1 mm in from) the margin; [subfamily Vaccinioideae; tribe Lyonieae]
............ ............ ............ ............ 25 Leaves without a prominent marginal vein.
............ ............ ............ ............ ..26 Corolla saucer-shaped, 10-30 mm across; leaves entire; [subfamily Ericoideae; tribe Phyllodoceae]
............ ............ ............ ............ ..26 Corolla narrowly urceolate, 4-6 mm across; leaves finely crenulate-serrulate; [subfamily Vaccinioideae; tribe Lyonieae]
............ ............ ............ ............ ....27 Flower stalks with 2 opposite or subopposite subulate bractlets a little below the calyx; leaves glabrous below or short-pubescent on the midvein
............ ............ ............ ............ ....27 Flower stalks with 2 opposite or subopposite triangular bractlets near the base of the pedicel; leaf lower surface punctate with stalked red glands
............ ............ ............ ....21 Leaves membranaceous or subcoriaceous, deciduous or evergreen, if subcoriaceous and evergreen, then not shiny and dark green above.
............ ............ ............ ............ ......28 Capsules elongate, > 2× as long as broad, 7-23 mm long; [subfamily Ericoideae; tribe Rhodoreae]
............ ............ ............ ............ ......28 Capsules ovoid to globose or subglobose, about as long as broad, or broader than long, 2-7 mm long.
............ ............ ............ ............ ........29 Leaves (at least the larger) > 2.5 cm wide.
............ ............ ............ ............ ............ 31 Capsule broader than long; shrub; bracteoles just below the calyx; [subfamily Vaccinioideae; tribe Gaultherieae]
............ ............ ............ ............ ............ 31 Capsule longer than broad; tree; bracteoles generally near the middle of the pedicel; [subfamily Vaccinioideae; tribe Oxydendreae]
............ ............ ............ ............ ............ ..32 Leaves entire to minutely serrulate; capsule sutures pale and thickened; [subfamily Vaccinioideae; tribe Lyonieae]
............ ............ ............ ............ ............ ..32 Leaves crenate; capsule sutures not thickened and pale; [subfamily Vaccinioideae; tribe Andromedeae]
............ ............ ............ ............ ............ ....33 Leaves linear to narrowly lanceolate, 8× or more as long as wide. strongly revolute, strongly whitened beneath; [subfamily Vaccinioideae; tribe Andromedeae]
............ ............ ............ ............ ............ ....33 Leaves broader, not revolute or slightly so, not strongly whitened below.
............ ............ ............ ............ ............ ......34 Leaves whorled or alternate; corolla saucer-shaped, 10-20 mm across; [subfamily Ericoideae; tribe Phyllodoceae]
............ ............ ............ ............ ............ ......34 Leaves alternate; corolla narrowly urceolate, 2-8 mm across.
............ ............ ............ ............ ............ ........35 Pedicels with 2 bracteoles near the summit; [subfamily Vaccinioideae; tribe Gaultherieae]
............ ............ ............ ............ ............ ........35 Pedicels with 2 bracteoles near the base; [subfamily Vaccinioideae; tribe Lyonieae]

Key to Ericaceae, Key D: Evergreen ericaeous shrubs (either tall or obviously clonal) and trees

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1 Leaves linear, needle-like, either appearing whorled (at least in part, sometimes also with nodes appearing opposite or alternate) or opposite (Calluna).
..2 Leaves opposite, sessile and clasping; [exotic, rarely naturalized]
..2 Leaves whorled (at least in part), petiolate (sometimes short-petiolate); [either native or exotic and rarely naturalized].
....3 Leaves densely puberulent and ciliate with gland-tipped hairs; leaves 1.5-5 mm long; [exotic, rarely naturalized]
....3 Leaves glabrous; leaves 2.5-15 mm long; [native].
......4 Plants erect shrubs 5-25 dm tall; leaves 5-15 mm long; drupes red, 1.5-2 mm in diameter; [of xeric or scrubby sites, SC southward]
......4 Plants subshrubs, erect or sprawling, stems 1.5-10 dm tall (or long in Empetrum); drupes gray or dark black, 1-1.5 mm (Corema) or 5-10 mm (Empetrum) in diameter; [dry sites, NJ northward].
........5 Stems prostrate, trailing; leaves 2.5-7 mm long, densely overlapping along stems; fruit a fleshy black drupe, 5-10 mm in diameter; flowers arranged on pedicels from leaf axils
........5 Stems upright, not trailing; leaves 3-6 mm long; fruit a dry gray drupe, 1-1.5 mm in diameter; flowers arranged in small terminal clusters
1 Leaves broader, alternate (or whorled or opposite in some Kalmia).
..........6 Leaves (all of them) < 2 cm long.
............ 7 [Either of the Mountains, the Piedmont, or the Coastal Plain of ne. SC and se. NC and northwards].
............ ..8 Leaves alternate, glabrous, finely serrulate
............ ..8 Leaves alternate or opposite, stipitate-glandular or glabrous, entire, or with a few obscure teeth
............ 7 [Of the Coastal Plain, from se. SC southward].
............ ....9 Twigs densely hispid; leaves hispid on both surfaces
............ ....9 Twigs glabrous to puberulent; leaves glabrous or with scattered inconspicuous hairs.
............ ......10 Plant glaucous and bluish-green throughout; leaf undersurface lacking scattered glandular hairs; [of s. GA south to s. peninsular FL, west to e. TX]
............ ......10 Plant dark green throughout, generally exceeding 20 mm in length; leaf undersurface with scattered glandular hairs, these sometimes very few by late in the season (best seen in the field by folding a leaf, holding the fold up to the light, and using a 10× lens); [of se. SC southward to n. FL, west to s. AL]
..........6 Leaves (at least the larger) > 3 cm long.
............ ........11 Leaves toothed, at least toward the tip of the leaf (note that fine serrations or crenations can be obscured by revolute margins).
............ ..........12 Leaves elliptic to oblanceolate, widest near or above the middle, obtuse, acute, or short-acuminate, 1.5-7 cm long, 0.5-2.5 cm wide; leaf serrations fine and obscure; leaf surfaces with small stipitate glands (Pieris) or lepidote with scales (Chamaedaphne).
............ ............ 13 Leaves lepidote with scales; leaves oblanceolate, widest above the middle
............ ............ 13 Leaves with small stipitate glands, otherwise appearing glabrous; leaves elliptic, widest near the middle.
............ ............ ..14 Inflorescence a many-flowered panicle of racemes, borne terminally; seeds 2.5-3 mm long; [of slopes and ridges of the Mountains and upper Piedmont]
............ ............ ..14 Inflorescence a 3-9 flowered raceme, borne in the axils of upper leaves; seeds ca. 1 mm long; [of wetlands of the Coastal Plain, often associated with Taxodium ascendens]
............ ..........12 Leaves lanceolate or ovate, widest below the middle, short-acuminate to acuminate, 4-15 cm long, 1-5 cm wide; leaf serrations generally obvious (at least toward the acuminate leaf tip); leaf surfaces glabrous, or with non-stipitate hairs on the lower surface.
............ ............ ....15 Pith transversely diaphragmed; [pedicels slender, 7-10 mm long]; [filaments strongly curved just below the anthers]
............ ............ ....15 Pith solid; [pedicels stout, 2-6 mm long]; [filaments straight].
............ ............ ......16 Leaves obtuse or acute to short-acuminate; staminal filaments almost always with at least a few unicellular hairs; calyx lobes ovate-triangular to ovate or widely so, 1.2-2.3 mm wide; racemes 0.9-5.5 cm long, with 8-44 flowers; sepals ovate, with an obtuse or rounded apex; longest petioles 2-10 (-11) mm long; [of the Coastal Plain and lower Piedmont]
............ ............ ......16 Leaves long-acuminate, petiole (5-) 6-16 mm long; staminal filaments merely papillose; calyx lobes ovate or ovate-triangular to oblong-triangular, 0.7-1.6 mm wide; racemes 2-10 cm long, with 17-80 flowers; longest petioles 8-15 mm long; [of the Mountains and upper Piedmont]
............ ........11 Leaves entire.
............ ............ ........17 Leaves densely pubescent beneath, either whitened beneath by a dense mat of fine white hairs or brown tomentose with coarse and twisted hairs; leaves strongly revolute
............ ............ ..........18 Leaves linear; leaf undersurface whitened beneath by a dense mat of fine white hairs
............ ............ ..........18 Leaves lanceolate or narrowly elliptic; leaf undersurface brown tomentose with coarse and twisted hairs
............ ............ ........17 Leaves glabrous, glabrescent, or lepidote with scales, appearing green or brownish; leaves planar, slightly revolute or strongly revolute.
............ ............ ............ 19 Leaves densely lepidote on the under surface with brown scales.
............ ............ ............ ..20 Leaves planar, not revolute; petioles 7-20 mm long; twigs more-or-less terete in cross-section; [of the Mountains, Piedmont, and upper Coastal Plain].
............ ............ ............ ....21 Corolla mostly 15-20 mm long, the corolla tube (9-13 mm long) shorter than to as long as the corolla lobes (12-18 mm long); plant flowering early relative to R. minus, despite occurring at higher elevations and more northern latitudes; seeds ovoid, < 1.0 mm long, < 2.5× as long as wide (reminiscent of tiny watermelon seeds), coarsely textured, unornamented at the ends; calyx lobes deltoid; [of mountain ridges, heath balds, and rocky summits, mostly either away from the Blue Ridge Escarpment or north of the Asheville Basin]
............ ............ ............ ....21 Corolla mostly 25-37 mm long, the corolla tube (13-22 mm long) longer than the corolla lobes (8-12 mm long); plant flowering late relative to R. carolinianum; seeds usually > 1.0 mm long, usually > 3× as long as wide, ornamented at one or both ends; calyx lobes ovate; [of the Coastal Plain, Piedmont, and Mountains, in the Mountains mostly of the Blue Ridge Escarpment of sw. NC and nw. SC, ranging in elevation up to the higher granitic domes in Macon and Jackson counties, NC].
............ ............ ............ ......22 Leaf apices mostly obtuse to rounded; petioles 2-6 (-7) mm long; branches erect and rigid; seeds moderately to elaborately ornamented with flared protrusions at both ends; [of n. FL]
............ ............ ............ ......22 Leaf apices mostly acute to acuminate; petioles (5-) 6-20 mm long; branches spreading, not notably erect and rigid; seeds somewhat ornamented at one end; [of c. GA northward]
............ ............ ............ ..20 Leaves slightly to strongly revolute (or nearly planar in Lyonia fruticosa); petioles 1-7 mm long; twigs angled in cross-section; [of the lower Coastal Plain, from se. SC southward].
............ ............ ............ ........23 Ultimate branches not rigidly ascending, flowers nearly always restricted to branches of the previous year, the leaves not conspicuously reduced toward the branch tips; leaves with distal margin usually revolute, sometimes strongly so; major veins usually depressed; lower leaf surface with some scales often large and with irregular margins, others smaller and more nearly entire, at least the smaller scales more-or-less persistent; [shrub or small tree to 6 (-10) m tall]
............ ............ ............ ........23 Ultimate branches rigidly ascending, flowers frequent on branches of the current year (though also on older growth), the leaves conspicuously reduced toward the branch tips; leaves with distal margin at most slightly revolute; major veins not depressed; lower leaf surface with scales usually all large and with irregular margins, the scales often deciduous; [shrub to 1.5 (-3) m tall]
............ ............ ............ 19 Leaves not lepidote beneath (Lyonia lucida with scattered minute scales on young leaves).
............ ............ ............ ..........24 Leaves whorled or rarely opposite.
............ ............ ............ ............ 25 Calyx lobes glandular-canescent and with marginal stipitate glands; leaves glabrous beneath; bracts and bracteoles densely glandular; stomates 18 μ long and 13 μ wide, 15-24 per 0.2 square millimeter; shrub to 1 (-1.2) m tall; [of ne. NC northward]
............ ............ ............ ............ 25 Calyx lobes canescent but lacking glands; leaves short puberulent beneath; bracts and bracteoles nearly glandless; stomates 13 μ long and 9 μ wide, 35-51 per 0.2 square millimeter; shrub to 2 m tall (though often much shorter); [of se. and sw. VA southward]
............ ............ ............ ............ ..26 Leaf blades (8-) 10-30 cm long, 3-9 cm wide, rounded to obtuse at the tip.
............ ............ ............ ............ ....27 Leaves rounded at base (rarely broadly cuneate or slightly cordate), obtuse at apex; leaf generally 1.5-2.5× as long as wide; corolla usually deep pink to purple; sepals 0.5-1 mm long
............ ............ ............ ............ ....27 Leaves cuneate at base, acute at apex; leaf generally 3-5× as long as wide; corolla usually white to pale pink; sepals 4-6 mm long
............ ............ ............ ............ ..26 Leaf blades 2-10 (-12) cm long, 1-5 cm wide, acute, short-acuminate (or obtuse or rounded in Cyrilla) at the tip.
............ ............ ............ ............ ......28 Leaf with a prominent vein running the length of the margin, about 1 mm in; [shrub to 4 m tall]
............ ............ ............ ............ ......28 Leaf venation not as above; [shrub to small tree] {Kalmia latifolia, Cyrilla, Cliftonia, Bejaria}
............ ............ ............ ............ ........29 Fruit a locular, dehiscent capsule, never winged; seeds usually present in fruit, very numerous, often 100-300 per fruit; [dry sites].
............ ............ ............ ............ ..........30 Stems hispid-tomentose (the hairs usually brown or rusty-colored); plants densely glandular, particularly along stems and flowers; capsules 7-locular; [endemic to xeric habitats in southeastern coastal plain, se SC to s. FL]
............ ............ ............ ............ ..........30 Stems glabrescent, viscid or stipitate-glandular (never hispid-tomentose); capsules 5-locular; flowers connate and strongly radially symmetric, campanulate, petals connate, [Creek and forest bluffs in n. FL and FL panhandle, otherwise primarily in drier piedmont and mountain sites n. to Ontario]
............ ............ ............ ............ ........29 Fruit an indehiscent drupe (winged or not); seeds usually absent from fruit, sometimes 1-5; [wet sites, except for Cyrilla arida].
............ ............ ............ ............ ............ 31 Racemes terminal and axillary; fruit 5-7 mm long, 2-5 winged
............ ............ ............ ............ ............ 31 Racemes only lateral, clustered together at the summit of previous year's growth and radiating outward or reflexed; fruit 2-2.5 mm long, not winged
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