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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).
image of plant
Show caption*© Keith Bradley
  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].
image of plant
Show caption*© Scott Ward
    3 Petals united; fruit nodding, a berry; flower and fruit several per stem
image of plant
Show caption*© Erik Danielson
    3 Petals separate; fruit erect, a capsule; flower and fruit 1-several per stem.
image of plant
Show caption*© Alan Cressler: Hypopitys lanuginosa, Chattahoochee National Forest, Rabun County, Georgia 1 by Alan Cressler
      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
image of plant
Show caption*© Keith Bradley
      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 yellow or reddish, 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.
                                                              30 Pedicels with 2 bracteoles.
                                                                 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]
                                                              30 Pedicels without bracteoles.
                                                                   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]
                                                            29 Leaves < 2.5 cm wide.
                                                                     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 G4: shrubs and subshrubs with alternate, simple, unlobed, entire leaves

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1 Leaves evergreen. {add to 1a: Scaevola in GOODENIACEAE, Morella (inodora) in MYRICACEAE, Ternstroemia in PENTAPHYLACACEAE, Myrsine in PRIMULACEAE, Pyracantha in ROSACEAE, Dodonaea in SAPINDACEAE, Cestrum in SOLANACEAE, Thymelaea in THYMELAEACEAE, Conocarpus in COMBRETACEAE}
  2 Leaves 1-7 mm long, either acicular and spreading or ovate and appressed to the stems
  2 Leaves > 10 mm long.
    3 Leaves linear, > 15× as long as wide; [Monocots]
    3 Leaves broader, < 15× as long as wide; [Eudicots, Basal Angiosperms, or Monocots].
      4 Plant a creeping subshrub, < 1 dm tall
      4 Plant not creeping, > 3 dm tall.
        5 Inflorescence an involucrate head
        5 Inflorescence solitary (Illicium in ILLICIACEAE) or variously branched, spicate, racemose, or fascicled, not an involucrate head.
          6 Carpels separate; fruit an aggregate; fresh foliage strongly fragrant; [Basal Angiosperms]
             7 Fruit an aggregate of woody follicles arranged in a whorl
             7 Fruit an aggregate of red to blackish berries, 4-6 mm long, each on a long stipe, giving the aggregate almost the appearance of an umbel
          6 Carpels fused; fruit a berry, drupe, acorn (nut), capsule, or legume; fresh foliage not strongly fragrant; [Eudicots, Monocots, and Basal Angiosperms].
               8 Ovary with 3 carpels; fruit a berry; “leaves” actually cladodes; [Monocots]
               8 Ovary with 1, 2, 3, 4, or 5 carpels; fruit a berry, drupe, capsule, legume, or nut; leaves actually leaves; [Eudicots and Basal Angiosperms].
                 9 Leaves largely covered with silver and/or bronze lepidote scales and/or dense stellate hairs below (visible at 10× or higher magnification), giving the lower leaf surface a slightly shiny to almost metallic appearance. {add Lyonia ferruginea and L. fruticosa in ERICACEAE; add Loropetalum in HAMAMELIDACEAE}
                   10 Petals present, conspicuous, connate, white, the corolla rotate; fruit a berry with several seeds; fresh foliage with a strong, tar-like odor
                   10 Petals absent or inconspicuous, greenish and separate if present (note that the calyx is petaloid and white or yellowish in Elaeagnus of ELAEAGNACEAE); fruit a dry capsule with 3 seeds, or a drupe with a single seed; fresh foliage lacking a strong odor.
                     11 Perianth 4-merous; petals absent; petaloid sepals white to cream, fused and salverform; carpel 1; fruit a fleshy, red drupe, with a single seed
                     11 Perianth 5-merous; petals green and separate, or absent; sepals greenish, separate; carpels 3; fruit a 3-valved capsule with 3 seeds
                 9 Leaves with various vestiture (or glabrous), but not as above.
                       12 Flowers in spikes, these solitary opposite leaves or in axillary umbels
                       12 Flowers in other types of inflorescences, not spikes.
                          13 Leaves 1-foliolate on the upper stems, sometimes 3-foliolate below, or all reduced to phyllodial spines; flowers papilionaceous, bright yellow; fruit a legume; stems bright green
                          13 Leaves simple throughout; flowers either small, inconspicuous, tannish, borne in catkins (Quercus), or larger and urceolate, or with almost separate and spreading petals, white to pink or reddish-orange, in various terminal or axillary, branched inflorescences; fruit either a nut in a cupule (an acorn), or a (3-) 5-valved capsule, or a spherical berry or drupe; stems generally brown or tan (sometimes green).
                            14 Flowers small, inconspicuous, tannish, borne in catkins; fruit a nut in a cupule (an acorn)
                            14 Flowers white to pink or reddish-orange, either urceolate or tubular or with separate and spreading petals, in various terminal or axillary inflorescences, or solitary; fruit either a (3-) 5-valved capsule, or a spherical berry with 10+ seeds, or a 1-8 seeded dry or fleshy drupe.
                              15 Flowers white to pink or reddish-orange, rotate or urceolate (the petals united at least basally), in various terminal or axillary inflorescences or solitary; fruit either a 2-5 valved capsule or a spherical berry with 10+ seeds.
                                16 Flowers reddish-orange; corollas bearing post-staminal hairs (appearing as tufts of hair opposite each anther)
                                16 Flowers white to pink; corollas without obvious tufts of hair opposite each anther.
                                  17 Leaves 1 per node or also paired (on one side of the stem) at some nodes (the leaves then uneven in size); inflorescences leaf-opposed; fruit a berry.
                                  17 Leaves 1 per node; inflorescences terminal or axillary, never leaf-opposed; fruit a valved capsule.
                                    18 Seeds without fleshy aril or attachment; ovaries 5-10 carpellate; flowers urceolate; leaves serrate or entire
                                    18 Seeds with fleshy aril or attachment; ovaries 2-4 carpellate; flowers rotate; leaves entire or very remotely serrulate.
                                       19 Flowers few, not showy, green to greenish-white, inflorescence not densely arranged (flowers also sometimes solitary); capsules not beaked; leaves not revolute or undulate
                                       19 Flowers numerous, showy, white; inflorescence densely arranged; capsules with short beak; leaf margins revolute or slightly undulate
                              15 Flowers white, petals spreading, separate even at the base, in axillary fascicles or racemes; fruit either a fleshy drupe with 4-8 pyrenes, or a dry single-seeded drupe.
                                         20 Shrub rhizomatous and colonial; fruit an ellipsoid drupe, 2-3 cm long
                                         20 Shrub not rhizomatous; fruit either a fleshy or dry drupe, < 1 cm long.
                                           21 Inflorescence an axillary fascicle or cluster; fruit a fleshy drupe with 4-8 pyrenes
                                           21 Inflorescence an axillary raceme; fruit a dry drupe with 1 seed
1 Leaves deciduous. {add: Ditrysinia in EUPHORBIACEAE, Glochidion in PHYLLANTHACEAE, Phyllanthopsis in PHYLLANTHACEAE, Nierembergia in SOLANACEAE, Edgeworthia in THYMELAEACEAE, Ipomoea (I. carnea) in CONVOLVULACEAE; Swida (S. alternifolia) in CORNACEAE}
                                             22 Inflorescence an involucrate head
                                             22 Inflorescence branched, spicate, a catkin, or consisting of a solitary flower or axillary clusters or whorls, not an involucrate head.
                                               23 Inflorescence a catkin; flowers unisexual; plants dioecious
                                                 24 Leaves 3.5-6 cm wide
                                                 24 Leaves < 3 cm wide
                                               23 Inflorescence various, not a catkin; flowers bisexual; plants hermaphroditic.
                                                    25 Inflorescences axillary, solitary flowers
image of plant
Show caption*© Michelle Wong, some rights reserved (CC BY), uploaded by Michelle W.
                                                      26 Fruit a globose, spinose capsule bearing a longitudinal ridge across 1 or both faces, thus essentially resembling a spikey ball; perianth (4-)5-merous, consisting of 3 upper connate petaloid claws and two lower sessile petals; fresh plants without a strange musky odor; [Eudicots]
                                                      26 Fruit an oblong berry, greenish-yellow when ripe, not bearing small spines; perianth 3-4-merous, without connate petaloid claws; fresh plants fragrant with a strange, musky odor; [Basal Angiosperms]
                                                    25 Inflorescence of 2 or more flowers; perianth 3-5-merous; fresh plants not musky-fragrant; fruits various, not as above.
                                                        27 Flowers 3-merous; fruit fleshy, red or greenish-yellow at maturity; ovary superior; [Basal Angiosperms or Eudicots].
                                                          28 Leaves elliptic or narrowly elliptic, broadest near the middle; fresh plants strongly fragrant with a citrus-like aroma; stems unarmed; fruit a drupe, with a single seed
                                                          28 Leaves obovate or oblanceolate, broadest near the apex; stems armed with nodal spines; fresh plants not fragrant; fruit a berry, with several seeds.
                                                        27 Flowers 4-5-merous; fruit fleshy or dry, black, blue, brown, tan, or red at maturity; ovary superior or inferior; [Eudicots].
                                                            29 Fruit a 4-5-valved capsule with many seeds; inflorescence either terminal, a corymb or panicle, or an axillary whorl
                                                            29 Fruit either a drupe or berry (indehiscent, and variously fleshy or dry) or a dry 3-valved capsule with 1 seed; inflorescence axillary (solitary, clusters, fascicles, or racemes), or in a terminal raceme (Pyrularia in SANTALACEAE).
                                                              30 Leaves largely covered with silver and/or bronze shiny lepidote scales below, giving the lower leaf surface an almost metallic appearance
                                                              30 Leaves with various vestiture, but not as above.
                                                                 31 Ovary inferior or half-inferior; inflorescence an axillary cluster or raceme, or a terminal raceme.
                                                                   32 Fruit a spherical berry, with 10 or more seeds
                                                                   32 Fruit an elongate drupe (definitely longer than thick), with 1 seed.
                                                                     33 Fruit 15-30 mm long; inflorescence a terminal raceme
                                                                     33 Fruit 6-10 mm long; inflorescence an axillary fascicle
                                                                 31 Ovary superior; inflorescence an axillary cluster or an axillary raceme (borne themselves in clusters).
                                                                       34 Fruits elongate, 8-20 mm long.
                                                                         35 Fruit a red or orange berry, 8-20 mm long; leaves usually on spur-shoots; [salty coastal areas, or exotics of disturbed situations]
                                                                         35 Fruit a yellowish-green drupe, 12-15 mm long; leaves on main stems; [rich forests, mainly inland]
                                                                       34 Fruits spherical, < 10 mm long.
                                                                           36 Inflorescence a narrowly cylindrical raceme, clustered several to many at the tip of the previous year’s wood and below the current season’s growth; fruit < 3 mm in diameter
                                                                           36 Inflorescence an axillary cluster; fruit > 4 mm in diameter
                                                                              37 Fruit dry, opening by 3 valves, 1-seeded; leaf pubescence stellate
                                                                              37 Fruit fleshy, with 4-8 seeds; leaf pubescence simple or absent.
                                                                                38 Fruit yellow to red, the pedicel 10-30 mm long; leaf venation pinnate, but irregular and reticulated
                                                                                38 Fruit dark red to black, the pedicel < 10 mm long; leaf venation very neatly pinnate, with the secondary veins nearly straight and parallel to one another

Key P1: herbaceous dicots with alternate, simple, and unlobed leaves on the stem

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1 Inflorescence an involucrate head subtended by phyllaries, the heads solitary or many and variously arrayed in secondary inflorescences, the ovary inferior, the corolla connate and tubular at least basally, the calyx absent, the stamens 5, the fruit a cypsela
1 Inflorescence, flower, and fruit structure various, but not with the combination of features as above (sometimes the flowers in a head, e.g. Eryngium in APIACEAE, but then with other features differing, such as stamens 4, or green calyx present, or fruit a schizocarp of mericarps, etc.).
  2 Perianth uniseriate (represented only by undifferentiated tepals or sepals) or completely absent; flowers usually unisexual, less commonly bisexual).
    3 Inflorescence a cyathium, consisting of a single pistillate flower (reduced to a single 3-carpellate pistil) and 2 or more staminate flowers (each reduced to 1 stamen), borne in a cup-like involucre, the involucre bearing pointed or rounded glands, these sometimes brightly colored and petaloid, mimicking an individual flower (the cyathia then secondarily arranged in terminal cymes, or solitary and axillary, etc.); fresh plants with milky juice; fruit a 3-lobed, 3-locular capsule
    3 Inflorescence not a cyathium (and staminate or bisexual flowers with > 1 stamen; fresh plants lacking milky juice (except Stillingia in EUPHORBIACEAE); fruit various, not as above.
      4 Leaf margins toothed in some manner (serrate, dentate, crenate, etc.)
        5 Leaf teeth rounded to subacute, resembling shallow lobes, irregular, few (mostly < 6 per leaf side).
          6 Fruit a single-seeded achene or utricle; [plants of various disturbed or saline, usually sunny habitats]
          6 Fruit a 3-lobed, circumscissilely dehiscent capsule; [plants native of rich moist shaded forests or exotics in suburban woodlands]
        5 Leaf teeth sharp to crenate, not lobe-like, regular, many (mostly > 10 per leaf side).
             7 Leaf bases cuneate
             7 Leaf bases cordate to rounded.
               8 Styles 3; fruit a 3-lobed, 3-carpellate capsule (1 carpel sometimes aborting); inflorescence either a terminal or leaf opposed raceme, or a dense axillary condensed cyme with conspicuous toothed bracts subtending the flowers
               8 Styles 1 or 2; fruit either an achene or a multiple of achenes; inflorescence either an axillary dense cyme (almost a head), or an axillary spike with glomerules, or a terminal or axillary panicle.
                 9 Styles 2; inflorescence a dense axillary cyme (almost a head); fruit a multiple of achenes; plant lacking stinging hairs; [exotic plant of weedy situations]
                 9 Style 1; inflorescence an axillary spikes with glomerules, or a terminal or axillary panicle; plant either with stinging hairs or not; [plant a rare exotic (Boehmeria nivea) or a native of moist forests (Boehmeria cylindrica, Laportea)]
      4 Leaf margins entire.
                   10 Ovary inferior or half-inferior.
                     11 Leaf base cordate; calyx 3-lobed, fused into a bilaterally symmetrical, curved brown or yellowish tube; fruit a capsule
                     11 Leaf base cuneate, rounded, or truncate; calyx of 3-4-5 distinct sepals, radially symmetrical, white or yellow; fruit a dry, nutlike drupe or an achene.
                       12 Leaves subsessile or very short petiolate, elliptic or narrowly elliptic, broadest near the middle; [native]
                       12 Leaves distinctly petiolate, rhombic, widest near the base; [rarely naturalized exotics].
                          13 Inflorescence of a single axillary flower
                          13 Inflorescence terminal, spikelike
                   10 Ovary superior.
                            14 Inflorescence a leaf-opposed (sometimes apparently terminal) spike or raceme; flowers visually white from white petaloid sepals, white bracts, or white stamens.
                              15 Sepals present, 4 or 5; petaloid, white; carpels 1 to many (-12); stamens 4 to many (-25); fruit a berry or an apically 2-lobed achene (as in Petiveria); leaf bases cuneate or rounded (but not cordate); [Eudicots].
                                16 Sepals 4; carpels 1; fruit subglobose berries or apically lobed achenes
                                16 Sepals 5; carpels 6-12, distinct; fruit an oblate berry
                              15 Sepals absent; carpels 3-4; stamens 2-6 (-8); fruit a capsule, a 1-seeded drupe, or a schizocarp of 3-4 mericarps; leaf bases cordate or subcordate; [Basal Angiosperms].
                                  17 Fruit a 1-seeded drupe; stamens 2; plants terrestrial or epiphytic
                                  17 Fruit a capsule or schizocarp with 3-4 mericarps; stamens 3 or 6-8; plants terrestrial
                            14 Inflorescence not leaf-opposed, either simpler (single axillary or glomerules of flowers) or more complexly branched (axillary or terminal panicles or complex cymes); flowers white, reddish, scarious, or greenish.
                                    18 Stipules tubular, sheathing (= ocreae); flowers subtended by tubular, sheathing bracteoles (= ocreolae); nodes usually prominently swollen; perianth usually of 5-6 white to pink tepals
                                    18 Stipules not tubular or sheathing; flowers not subtended by ocreolae; nodes not swollen; perianth absent or of 3-5 sepals.
                                       19 Inflorescence an terminal involucrate cluster; flowers bisexual; stamens 9
                                       19 Inflorescence axillary, or a terminal panicle or raceme that is not involucrate; stamens 3-6.
                                         20 Ovary 3-locular; styles 3, each bifid; fruit a capsule, with 6 seeds
                                         20 Ovary 1-locular; styles 1-3, not bifid; fruit a utricle or achene (1-seeded).
                                           21 Styles 1, stigma 1; flowers unisexual
                                           21 Styles 1-3, if style 1, then stigmas 3; flowers bisexual or unisexual.
                                             22 Tepals acute, scarious
                                             22 Tepals usually blunt, herbaceous
  2 Perianth biseriate (represented by differentiated whorls of sepals and petals, the sepals usually green or drab in color, the petals often brightly colored); flowers nearly always bisexual (there are exceptions).
                                               23 Ovary inferior or half-inferior.
                                                 24 Petals connate.
                                                    25 Inflorescence leaf-opposed, a dense, cylindrical spike
                                                    25 Inflorescence various, either a terminal head, or axillary and solitary, or variously axillary or terminal and more diffuse.
                                                      26 Leaves toothed; flowers blue to white
                                                      26 Leaves entire; flowers white
                                                 24 Petals distinct.
                                                        27 Petals 5; stamens 5; inflorescence a head; fruit a schizocarp of 2 mericarps
                                                        27 Petals 4 7; stamens 6 or more; inflorescence various, not a head; fruit a capsule.
                                                          28 Petals 4-7; stamens 1× or 2× as many as the petals, 4-7, 8, 10, 12, or14; leaves herbaceous in texture
                                                          28 Petals 5 (or sometimes doubled in horticultural forms); stamens 6-40 (or more); leaves fleshy in texture
                                               23 Ovary superior.
                                                            29 Corolla bilaterally symmetrical, petals connate (except distinct in VIOLACEAE); fruit a capsule or legume (except a 1-seeded indehiscent spinose pod in Krameria in KRAMERIACEAE).
                                                              30 Petals distinct, 5; carpels 3; fruit a 3-loculed capsule
                                                              30 Petals connate (at least basally), 4, 5, 6, 7, or 8; carpels 1, 2, 4, 5, or 6 (rarely 3 in Reseda in RESEDACEAE); fruit a legume or 1-, 2-, or 5-loculed capsule (except a 1-seeded indehiscent pod in Krameria in KRAMERIACEAE).
                                                                 31 Stamens 6-10 (-25), more than the number (4 or 5) of petals and the number (4 or 5) of the sepals; fruit a legume or a 1-6-carpellate capsule.
                                                                   32 Stamens fused, monadelphous or diadelphous.
                                                                     33 Stamens 10, monadelphous or diadelphous; fruit a legume
                                                                     33 Stamens 6-8, monadelphous; fruit a capsule
                                                                   32 Stamens distinct.
                                                                       34 Carpel 1; fruit a legume
                                                                       34 Carpels 3-6; fruit a capsule
                                                                 31 Stamens 4-5, less than the number (5) of the petals; fruit a 2-5-carpellate capsule.
                                                                         35 Pistil 5-carpellate; capsule 5-locular, explosively dehiscent; inflorescence axillary, small clusters of flowers
                                                                         35 Pistil 2-carpellate; capsule 2 locular, opening gradually or not at all; inflorescence a terminal spike, raceme or panicle (or solitary, axillary flowers in Chaenorrhinum in PLANTAGINACEAE and Krameria in KRAMERIACEAE).
                                                                           36 Fruit 1-seeded, indehiscent; sepals petaloid, red-purple; petals dimorphic, the upper 3 long-clawed, the lower 2 small, thickened, and glandlike
                                                                           36 Fruit > 2-seeded, dehiscent; sepals sepaloid, green; petals not dimorphic.
                                                                              37 Stamens 5; corolla not spurred; capsule septicidal; pubescence of the stem and leaves either gland-tipped or dendritically branched
                                                                              37 Stamens 4; corolla with a distinct spur or sac at the base between the the 2 lower calyx lobes (except not spurred in Digitalis and Schwalbea); capsule loculicidal (only at the summit in Antirrhinum and Chaenorrhinum, and septicidal in Schwalbea); pubescence of the stem and leaves neither gland-tipped (except in Antirrhinum and Chaenorrhinum) nor dendritically branched.
                                                                                38 Capsule septicidal; corolla not spurred
                                                                                38 Capsule loculicidal; corolla spurred (except Digitalis)
                                                            29 Corolla radially symmetrical, petals connate or distinct; fruit various (including a capsule).
                                                                                  39 Petals distinct; stamens 5-many.
                                                                                    40 Pistils 4-10 (each 1-carpellate) in a ring, these sometimes fused basally, each with its own style/stigma; fruit either an aggregate of achenes or follicles or a 5 (-7) locular capsule.
                                                                                      41 Pistils 5 (-7); inflorescence a compound terminal cyme.
                                                                                        42 Fruit an aggregate of follicles; leaves fleshy in texture; inflorescence; leaves entire of sparsely and coarsely serrate, with < 12 points per leaf; [plants primarily of dry habitats]
                                                                                        42 Fruit a 5 (-7) locular capsule; leaves membranaceous in texture; leaves serrate, with > 20 points per leaf; [plants of wet habitats]
                                                                                      41 Pistils many; inflorescence of solitary flowers, or diffuse.
                                                                                           43 Leaves cuneate at the base; flowers in a diffuse inflorescence
                                                                                           43 Leaves cordate at the base; flowers solitary, on long pedicels
                                                                                    40 Pistil 1, with 1-to many carpels (in many MALVACEAE, the carpels loosely united in a ring [of more than 5] around the single style/stigma); fruit either a 1-, 2-, 3-, 5-, 6-, or 10-locular capsule, or a silique/silicle, or a ring of mericarps.
                                                                                             44 Petals 4; sepals 4; stamens 6; fruit a silique/silicle
                                                                                             44 Petals 5 (rarely 4 or 6); sepals 5 (rarely 4 or 6); stamens 5 (or multiples of 5), 6, or 12; fruit a capsule or a ring of mericarps.
                                                                                               45 Stamens many, connate into a staminal tube; carpels 5-many; fruit a capsule or ring of mericarps; leaves usually serrate
                                                                                               45 Stamens 5-many, distinct; carpels 2-5; fruit a capsule; leaves entire (serrate in Croton in EUPHORBIACEAE).
                                                                                                 46 Flowers unisexual; leaf vestiture of peltate scales and/or stellate hairs
                                                                                                 46 Flowers bisexual; leaf vestiture simple or stellate.
                                                                                                   47 Flowers 6-merous (the petals and sepals 6, the stamens 6 or 12); corolla pink or purplish (rarely white); fruit a septicidal capsule
                                                                                                   47 Flowers 5-merous (the petals and sepals 5, stamens 5 or various multiples of 5); corolla yellow, reddish, or blue; fruit a loculicidal or septicidal capsule.
                                                                                                     48 Stamens 5; corolla yellow or blue; capsule either 10-locular and septicidal or 1-locular (with 3 carpels) and loculicidal.
                                                                                                        49 Capsule 10-locular (with 5 carpels) and septicidal
                                                                                                        49 Capsule 1-locular (with 3 carpels) and loculicidal
                                                                                                     48 Stamens (5-) 10, 15, 20, 30 (-many); corolla white, pink, yellow, or reddish; capsule 3-, 5- (-10)-locular, loculicidal.
                                                                                                          50 Stamens (5-) 10, 15, 20, 30 (-many); corolla yellow or reddish; capsule 3 (-10)-locular, loculicidal
                                                                                                          50 Stamens 10; corolla white or pink; capsule 5-locular
                                                                                  39 Petals fused; stamens (4-) 5 (-7).
                                                                                                            51 Pistils 2, united only by the style and stigma; fruit a schizocarp of 2 follicles (often single by abortion); plant with milky juice when fresh; leaves entire; inflorescence an umbel
                                                                                                            51 Pistil 1 (of 2 or 3 fused carpels); fruit a capsule; plant lacking milky juice; leaves entire or serrate; inflorescence various (but not an umbel).
                                                                                                              52 Ovary slightly to deeply 2-4-lobed; fruit a schizocarp of 4 mericarps or a drupe.
                                                                                                                53 Ovary deeply 4-parted; style gynobasic; fruit a schizocarp of 4 mericarps
                                                                                                                53 Ovary slightly 2-4-lobed, or not at all lobed; style terminal or reduced to a sessile terminal stigma; fruit a schizocarp of 4 mericarps, or a drupe
                                                                                                              52 Ovary not lobed; fruit a capsule or berry.
                                                                                                                  54 Leaves scale-like, 1-4.5 mm long, appressed to the stem; petals 4; stamens 4
                                                                                                                  54 Leaves larger (or only 2-8 mm long in Pyxidanthera in DIAPENSIACEAE, but then spreading); petals 5-7; stamens 5-7.
                                                                                                                     55 Plant a creeping subshrub (keyed here as a failsafe); leaves either 0.2-0.8 cm long and acicular, or 2-10 cm long and broadly ovate or elliptic.
                                                                                                                       56 Leaves 0.2-0.8 cm long and acicular
                                                                                                                     55 Plant an herb, erect or sprawling; leaves > 1.5 cm long.
                                                                                                                         57 Leaves cordate at the base; plant a twining vine
                                                                                                                         57 Leaves cuneate to rounded at the base; plant an erect, sprawling, or reclining herb (twining in Solanum dulcamara in SOLANACEAE).
                                                                                                                           58 Inflorescences (solitary or of several flowers) terminal on the stem.
                                                                                                                             59 Corolla lobes longer than the fused corolla cup, blue, pink, or white; styles 2; herbage lacking stipitate glands; fresh plants not aromatic.
                                                                                                                               60 Flowers in axillary cymes; capsule subglobose; leaves 2-12 cm long
                                                                                                                               60 Flowers solitary or paired in the leaf axils; capsule cylindrical; leaves 0.5-8 cm long
                                                                                                                             59 Corolla lobes very short, much shorter than the corolla cup or tube, sometimes barely perceptible and represented only by teeth on the edge of the corolla limb, white or pink; style 1; herbage often with stipitate glands; fresh plants often rankly aromatic
                                                                                                                           58 Inflorescences (of solitary or several flowers) axillary or lateral on the stem.
                                                                                                                                  61 Flowers sessile or very-short pedicelled, solitary in the leaf axils.
                                                                                                                                    62 Stamens alternate with the corolla lobes; flower ca. 10 mm in diameter
                                                                                                                                    62 Stamens opposite the corolla lobes; flower ca. 1 mm in diameter
                                                                                                                                  61 Flowers either solitary and obviously pedicelled, or several in an axillary or lateral inflorescence.
                                                                                                                                      63 Corolla lobes longer than the fused corolla cup, blue
                                                                                                                                      63 Corolla lobes very short, much shorter than the corolla cup or tube, sometimes barely perceptible and represented only by teeth on the edge of the corolla limb, white, yellow, pink, various other colors (rarely including blue).
                                                                                                                                        64 Fruit a capsule, 4-seeded
                                                                                                                                        64 Fruit a berry or capsule, many-seeded