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Keyed in multiple places:

Key to Ranunculaceae

1 Shrub or vine; leaves compound (or sometimes some to most of them simple in Clematis).
..2 Leaves opposite, distributed along the stem; sepals 4, white to blue or purplish, 10-50 mm long; wood not yellow; [subfamily Ranunculoideae, tribe Anemoneae]
..2 Leaves alternate, clustered together at the top of the usually unbranched, erect stem; sepals 5, maroon, 2-5 mm long; wood yellow; [subfamily Coptidoideae]
1 Herb; leaves compound or simple.
....3 Leaves simple, sometimes deeply cleft or lobed into rounded or elongate segments; [subfamily Ranunculoideae].
......4 Plants in flower
......4 Plants in fruit
....3 Leaves compound, the leaflets either linear or more-or-less petiolulate.
........5 Plants in flower
........5 Plants in fruit

Key A: Subkey in Ranunculaceae

1 Flowers bilaterally symmetrical, the upper sepal hooded or spurred; [tribe Delphinieae].
..2 Upper sepal hooded or helmet-shaped; petals hidden by the sepals; perianth blue or creamy white; stems weak, clambering, reclining, vining, or ascending in a curve
..2 Upper sepal spurred; petals at least partly exserted from the sepals; perianth blue, pink, white, or greenish; stems strong, erect, normally straight
1 Flowers radially symmetrical, no perianth parts spurred or hooded (except the 5 sepals spurred in Myosurus).
....3 Petals present, white or yellow, larger and more conspicuous than the sepals; sepals present, green; [in other words, with a second, green, less conspicuous perianth whorl below the largest and colored perianth whorl; note that some Anemone have a calyx-like involucre of 3 bracts subtending each flower]; [tribe Ranunculeae].
......4 Basal leaves linear to linear-spatulate, mostly 4-8 cm long, 1-3 mm wide; receptacle elongate, 1-6 cm long (superficially resembling a Plantago inflorescence)
......4 Basal leaves various, but not as above; receptacle globose to sub-cylindric, mostly < 1 cm long
........5 Sepals 3 (-4); petals 7-12; achenes pubescent, beakless; leaves simple, cordate, unlobed; [introduced garden plants]
........5 Sepals (3-) 5 (-6); petals typically 5-9 (10 in some "doubled" forms); achenes smooth or variously ornamented with spines, papillae, or tubercles, sometimes also pubescent; leaves various, usually not at once simple, cordate, and unlobed (except in Halerpestes); [native or introduced].
..........6 Cauline leaves absent; basal leaves cordate, unlobed
..........6 Cauline leaves present, well-developed; basal leaves not simultaneously cordate and unlobed
....3 Petals absent (or modified into relatively inconspicuous nectaries or staminodia); sepals present and petaloid (white, yellow, yellow-green, cream, or blue).
............ 7 Petaloid sepals 3-5 mm long, caducous; stamens white and showy; [tribe Ranunculeae]
............ 7 Petaloid sepals 6-40 mm long, not caducous; stamens not notably white and showy.
............ ..8 Leaves opposite, distributed along the stem; style plumose; [tribe Anemoneae]
............ ..8 Leaves all basal, or with a few alternate or whorled involucrate leaves on the stem; style not plumose.
............ ....9 Petaloid sepals white, bluish, or blue; basal leaves 3-5 (-7)-lobed; [tribe Anemoneae]
............ ......10 Leaves lobed, and also toothed and variously cleft; leaves not variegated
............ ......10 Leaves lobed, the margins of the lobes entire; leaves often prominently variegated
............ ....9 Petaloid sepals yellow, green, or whitish (sometimes marked with purple); basal leaves unlobed, or palmately cleft into 5-11 (-many) segments.
............ ........11 Leaves cordate-reniform, unlobed; sepals bright yellow; petals absent; [native, of bogs and marshes]; [tribe Caltheae]
............ ........11 Leaves palmately or pedately lobed or divided; sepals green, greenish, dull yellow, or whitish; petals modified into tubular nectaries; [introduced, rarely persistent or escaped from cultivation].
............ ..........12 Sepals 5, green or maroon, persistent in fruit; cauline leaves present; leaf margins sharply and finely serrate; [tribe Helleboreae]
............ ..........12 Sepals 5-8, yellow; cauline leaves either present, alternate, or absent, except for the involucre of 3 bracts which immediately subtends the flower.
............ ............ 13 Cauline leaves absent, except the 3 involucral bracts immediately subtending the flower; [tribe Cimicifugeae]
............ ............ 13 Cauline leaves present, alternate, the uppermost > 1 cm below the flower; [tribe Helleboreae]

Key B: Subkey in Ranunculaceae

1 Fruit a follicle, each carpel with 2 or more ovules.
..2 Leaves cordate-reniform, toothed, not lobed or divided; [tribe Caltheae]
..2 Leaves variously palmately or pedately lobed or divided.
....3 Carpels 1-3; plants 3-30 dm tall; [native, except Consolida]; [tribe Delphinieae].
......4 Stems weak, clambering, reclining, or vining
......4 Stems strong, erect
....3 Carpels 3-6; plants 1-5 dm tall; [introduced, rarely persistent or escaping].
........5 Cauline leaves absent, except for the involucre which immediately subtends the fruit; [tribe Cimicifugeae]
........5 Cauline leaves present; [tribe Helleboreae].
1 Fruit an achene (or dehiscent utricle in Trautvetteria), each carpel with 1 ovule.
..........6 Leaves opposite, distributed along the stem; style plumose; [tribe Anemoneae]
..........6 Leaves all basal, or with a few alternate or whorled involucrate leaves on the stem; style not plumose.
............ 7 Basal leaves linear to linear-spatulate, mostly 4-8 cm long, 1-3 mm wide; receptacle elongate, 1-6 cm long (superficially resembling a Plantago inflorescence); [tribe Ranunculeae]
............ 7 Basal leaves various, but not as above, generally long-petiolate, with an expanded, crenate-toothed, 3-lobed, or palmately-lobed blade; receptacle globose to sub-cylindric, mostly < 1 cm long.
............ ..8 Fruit a dehiscent utricle; cauline leaves alternate; [tribe Ranunculeae]
............ ..8 Fruit an achene; cauline leaves opposite or whorled (or alternate in Ranunculus, or reduced to alternate scale-like bracts in Halerpestes).
............ ....9 Cauline leaves opposite or whorled, or reduced to 3 sepal-like involucral bracts immediately subtending the flower; sepals absent (but in “Hepatica” mimicked by the bracts); [tribe Anemoneae]
............ ......10 Leaves lobed, and also toothed and variously cleft; leaves not variegated
............ ......10 Leaves lobed, the margins of the lobes entire; leaves often prominently variegated
............ ....9 Cauline leaves alternate; sepals present; [tribe Ranunculeae]
............ ........11 Achenes smooth or variously ornamented with spines, papillae, or tubercles, sometimes also pubescent, usually noticeably beaked, the beak > 0.3 mm long; leaves various, usually not at once simple, cordate, and unlobed ; [native or introduced]
............ ........11 Achenes not ornamented with spines, papillae, or tubercles, pubescent or glabrous, beakless; leaves simple, unlobed.
............ ..........12 Sepals 3; [introduced garden plants]
............ ..........12 Sepals 5; [native, of s. NJ northwards]

Key C: Subkey in Ranunculaceae

1 Leaflets linear, < 1.5 mm wide.
..2 Flowers bilaterally symmetrical; [subfamily Ranunculoideae, tribe Delphineae]
..2 Flowers radially symmetrical.
....3 Aquatic; [native]; [subfamily Ranunculoideae, tribe Ranunculeae]
....3 Terrestrial; [alien].
......4 Flower closely subtended by a finely dissected involucre; pistils compound; [subfamily Ranunculoideae, tribe Nigelleae]
......4 Flower lacking involucre; pistils simple.
........5 Petals 8-15 mm long, red, purple, or orange; [subfamily Ranunculoideae, tribe Adonideae]
........5 Petals 3-5 mm long, yellow; [subfamily Ranunculoideae, tribe Ranunculeae]
1 Leaflets broader, rounded, lobed, or toothed.
..........6 Leaves all cauline, opposite; stems somewhat woody at base; [subfamily Ranunculoideae, tribe Anemoneae]
..........6 Leaves basal and cauline, the cauline alternate (or with opposite or whorled involucral bracts).
............ 7 Petals present, conspicuous
............ ..8 Flowers dangling; petals red, orange with yellow, or blue, spurred; [subfamily Thalictroideae]
............ ..8 Flowers not dangling; petals yellow, not spurred; [subfamily Ranunculoideae, tribe Ranunculeae]
............ 7 Petals absent or inconspicuous (soon deciduous or altered into a nectary-bearing clavate structure); sepals sometimes petaloid and conspicuous.
............ ....9 Sepals petaloid, conspicuous, white (or cream, rose, pink, or tinged with green).
............ ......10 Involucre absent, all leaves on the stem alternate; petaloid sepals 5, white; [subfamily Thalictroideae]
............ ......10 Involucre of opposite or whorled, leaflike bracts present; petaloid sepals (4-) 5-20 (-30), white, cream, rose, or green.
............ ........11 Basal leaves with 3-5 leaflets, these toothed or incised; petaloid sepals white, cream, rose, or green; [subfamily Ranunculoideae, tribe Anemoneae]
............ ........11 Basal leaves with > 5 leaflets; these with 0-3 rounded lobes at the tip; petaloid sepals white to pale pink; [subfamily Thalictroideae]
............ ....9 Sepals absent, or inconspicuous in comparison to the stamens or pistils.
............ ..........12 Leaflets 3; flower solitary; [subfamily Coptidoideae]
............ ..........12 Leaflets many; flowers many, in a panicle or raceme.
............ ............ 13 Inflorescence a raceme; [subfamily Ranunculoideae, tribe Cimicifugeae]
............ ............ 13 Inflorescence a panicle; [subfamily Thalictroideae]

Key D: Subkey in Ranunculaceae

1 Fruit a follicle or capsular (or fleshy and berrylike in some Actaea).
..2 Mature leaves > 4 dm wide; [subfamily Ranunculoideae, tribe Cimicifugeae]
..2 Mature leaves < 3 dm wide.
....3 Leaflets linear; [aliens].
......4 Flowers in a raceme, not subtended by an involucre; fruit follicular, each with a 1-2 mm long beak; [subfamily Ranunculoideae, tribe Delphineae]
......4 Flower solitary, subtended by a finely divided involucre; fruit a spherical capsule-like structure composed of 5 or 10 partially connate follicles, each follicle terminated by a linear beak 13-20 mm long; [subfamily Ranunculoideae, tribe Nigelleae]
....3 Leaflets broad, rounded; [mostly natives].
........5 Follicles borne on stipes, forming an umbel-like cluster; rhizomes yellow or orange; [subfamily Coptidoideae]
........5 Follicles sessile; rhizomes brown or tan; [subfamily Thalictroideae].
..........6 Follicles 15-31 mm long, with beaks 7-18 mm long
..........6 Follicles 3.5-6.5 mm long, with beaks 1.5-3 mm long
1 Fruit an achene.
............ 7 Leaves divided into numerous linear segments, all of which are < 1 mm wide.
............ ..8 Plant aquatic (if leaves divided into numerous linear segments); [subfamily Ranunculoideae, tribe Ranunculeae]
............ ..8 Plant terrestrial.
............ ....9 Achenes 3-5 mm long, glabrous, with a persistent beak 0.5-1 mm long; [subfamily Ranunculoideae, tribe Adonideae]
............ ....9 Achenes 1.6-2 mm long, tometose, with a persistent beak 3.5-4.5 mm long; [subfamily Ranunculoideae, tribe Ranunculeae]
............ 7 Leaf segments rounded or cleft, > 1 mm wide.
............ ......10 Leaves cauline, opposite; [subfamily Ranunculoideae, tribe Anemoneae]
............ ......10 Leaves basal and/or cauline, cauline leaves (if present) alternate (leaflike involucral bracts sometimes present and opposite or whorled).
............ ........11 Leaflike involucral bracts present, opposite or whorled.
............ ..........12 Achenes not ribbed or veined on lateral surfaces; leaf texture moderate to distinctly thick and leathery; [subfamily Ranunculoideae, tribe Anemoneae]
............ ..........12 Achenes conspicuously ribbed or veined on lateral surfaces; leaf texture thin, delicate; [subfamily Thalictroideae]
............ ........11 Leaflike involucral bracts not present.
............ ............ 13 Leaflets 3-many, if many the leaflets typically with teeth, or sharp lobes; [subfamily Ranunculoideae, tribe Ranunculeae]
............ ............ 13 Leaflets many, unlobed or typically with 3-9 rounded lobes; [subfamily Thalictroideae]

Key I: woody plants with opposite, compound leaves

1 Leaves 2-3-foliolate.
..2 Leaves 2-foliolate, with a branched tendril in the terminal position (this sometimes not developed, or withered); liana
..2 Leaves 3-foliolate, lacking tendrils; shrub, liana, or tree.
....3 Upright shrub or tree.
......4 Leaflets entire, glandular-dotted; [n. FL southwards
......4 Leaflets serrate or serrulate, not glandular-dotted; [collectively widespread].
........5 Leaflets 3-5 (-7), coarsely and jaggedly serrate, with < 5 teeth per leaflet side; fruit a schizocarp of 2 samaroid mericarps (maple “keys”)
........5 Leaflets 3, evenly serrulate, with > 10 teeth per leaflet side; fruit an inflated capsule
....3 Liana or sprawling shrub.
..........6 Flowers yellow with fused petals; stems stiff, green
..........6 Flowers either white, radially symmetrical, with separate petaloid sepals (Clematis), or blue, bilaterally symmetrical, with fused petals (Vitex).
............ 7 Leaves 3-more-foliolate; flowers white, radially symmetrical, uniseriate, with white petaloid sepals and no petals
............ 7 Leaves 1 (-3) foliolate; flowers blue, bilaterally symmetrical, biseriate, with green calyx and blue corolla
1 Leaves 4-15-foliolate.
............ ..8 Leaves palmately compound.
............ ....9 Leaflets serrate; flowers white, yellow, or red; fruit a leathery capsule, irregularly spheroidal, 2-9 cm in diameter, with 1-3 (-6) large seeds, each with a large pale hilum contrasting with the dark brown color of the rest of the seed
............ ....9 Leaflets entire; flowers blue, pink, or purple; fruit either a 4-seeded drupe, < 0.5 cm in diameter, or an elongated capsule, 8-10 cm long and ca. 0.7 cm in diameter.
............ ......10 Leaflets < 3× as long as wide, broadly rounded at the tip; fruit an elongated capsule, 8-10 cm long and ca. 0.7 cm in diameter [peninsular FL]
............ ......10 Leaflets > 4× as long as wide, acute at the tip; fruit a 4-seeded drupe, < 0.5 cm in diameter; [widespread in our region]
............ ..8 Leaves pinnately compound, bipinnately compound, or more complexly compound.
............ ........11 Plant a liana (woody vine).
............ ..........12 Leaves pinnately compound, with 7-15 coarsely serrate leaflets; perianth biseriate, with a green synsepalous calyx and an orange sympetalous corolla; fruit an elongate capsule, with many winged seeds; stems to 20 cm in diameter, with tan bark
............ ..........12 Leaves either pinnately compound, the leaflets 3-7 and coarsely serrate, or more complexly compound, the leaflets 5-many, not serrate though often lobed; perianth uniseriate, with a white, pink, or purplish aposepalous calyx and no corolla; fruit an aggregate of plumose achenes; stems to 1 cm in diameter, brown or green
............ ........11 Plant a tree or shrub, with stiff branches.
............ ............ 13 Leaves 3-7-foliolate and strictly 1-pinnate; leaflets with a few very coarse teeth; 1st year stems green; fruit a pair of winged, asymmetrical samaroid mericarps
............ ............ 13 Leaves 3-15-foliolate, 1-pinnate or partially 2-pinnate; leaflets evenly serrate with many teeth or entire; 1st year stems tan to brown (very new growth may be green); fruit either a symmetrical (winged) samara (Fraxinus) or a purplish-black, many-seeded berry (Sambucus).
............ ............ ..14 Fruit a purplish-black or red, 4-seeded berry (Sambucus); plant a shrub or small tree; stems hollow or pithy; petiole prominently grooved on the upper side; fresh leaves somewhat fleshy in texture
............ ............ ..14 Fruit either a green or tan, symmetrical (winged) samara or a blackish 5-seeded dryish drupe; plant a small to large tree; stems solid and woody; petiole nearly round in ×-section (not grooved); fresh leaves membranaceous or coriaceous in texture.
............ ............ ....15 Fruit a symmetrical samara; axillary buds suprapetiolar (though sometimes almost hidden within the strongly U-shaped petiolar attachment; [common native (also planted)]
............ ............ ....15 Fruit a nearly spherical 5-seeded dry drupe; axillary buds infrapetiolar (hidden by the swollen petiole base; [rarely escaped alien]

Key R: herbaceous dicots with opposite, compound leaves on the stem

1 Inflorescence an involucrate head subtended by phyllaries, heads solitary or many, variously arrayed in secondary inflorescences; fruit a cypsela
1 Inflorescence various, but not as above; fruit various, not as above.
..2 Leaves pinnately compound.
....3 Leaves even-pinnate
....3 Leaves odd-pinnate.
......4 Plants vines, sclimbing or sprawling, the leaves often with tendril like petioles and leaf rachises; corolla 4-parted, radially symmetrical
......4 Plants not vines, more or less erect to arching and lacking adaptations for climbing; corolla 5-parted, radially or bilaterally symmetrical
........5 Plants often with a mix of mostly opposite, deeply 3-lobed leaves or trifoliate leaves (leaves sometimes simple); flowers pink or purplish-white, axillary; plants annual
........5 Plants typically with all leaves with > 3 leaflets; flowers primarily white, borne in dense terminal corymbs/cymes; plants perennial
..2 Leaves palmately compound.
..........6 Cauline leaves essentially sessile, and also palmately cleft to the base, and further lacerately divided into linear or oblanceolate segments
..........6 Cauline leaves petiolate, with 3-5, sessile or petiolulate, ovate, elliptic, or obovate leaflets (these serrate and sometimes with additional lobes).
............ 7 Plants annual; flowers typically unisexual and not showy, green; plants highly resinous and glandular; inflorescences variously arranged
............ 7 Plants perrenial; flowers radially symmetric, showy, variously colored; plants typically not strongly resinous or glandular; inflorescences terminal

Key S1: herbaceous dicots with opposite, simple, and unlobed leaves on the stem

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. Pycnanthemum in LAMIACEAE, but then with other features differing, such as stamens 4, or green calyx present, or fruit a schizocarp of mericarps, etc.).
..2 Leaves scale-like, stems fleshy; flowers embedded in the fleshy stem, no perianth present; [saline environments (coastal or rarely inland)].
..2 Leaves small to large; stems not fleshy; flowers sessile or on pedicels; [collectively of many habitats, saline and not].
....3 Ovary inferior or partially inferior.
......4 Perianth of a single whorl (petals absent) (note that in Mirabilis in NYCTAGINACEAE the petaloid calyx is subtended by a 5-lobed fused set of involucral bracts).
........5 Leaves herbaceous, suborbicular, about as long as wide or wider than long; calyx 3- or 4-merous; stamens 4, 8, or 12.
..........6 Plant ascending, with a single node (2 leaves); leaves > 6 cm long and wide; calyx 3-merous, brown to yellowish; stamens 12
..........6 Plant creeping, with many nodes; leaves 3-15 mm long and wide; calyx 4-merous, yellow to greenish; stamens 4 or 8
........5 Leaves fleshy, linear, lanceolate, to broadly ovate, at least slightly longer than broad; calyx 5-merous; stamens 3, 5, or 10.
............ 7 Flowers axillary, sessile or nearly so, solitary or a few; petaloid sepals widely spreading, separate; leaves linear to oblanceolate; stamens 5 or 30-50
............ 7 Flowers in terminal cymose panicles; petaloid sepals connate into a narrow tube (reminiscent of the corolla of Ipomoea); leaves lanceolate, elliptic, ovate, or broadly ovate; stamens 3 or 5
......4 Perianth in 2 whorls (sepals and petals both present).
............ ..8 Petals distinct; inflorescence diffuse.
............ ....9 Leaves distinctly 3-veined from the base, the 3 veins converging again at the leaf apex
............ ....9 Leaves with prominently pinnate venation
............ ..8 Petals connate into a tube (at least basally); inflorescence often a head or dense terminal cyme (also axillary, or solitary on long peduncles).
............ ......10 Petals 5; stamens 3, 4, or 5
............ ........11 Creeping subshrub; flowers paired at tip of an upright peduncle
............ ........11 Upright herb; flowers in axils or terminal corymbs
............ ..........12 Flowers in terminal corymbs; fruit dry
............ ..........12 Flowers axillary; fruit fleshy
............ ......10 Petals 4 (or 6 or 8 in Richardia in RUBIACEAE); stamens 4, 6, or 8.
............ ............ 13 Inflorescence a head, subtended by 4 large bright white bracts
............ ............ 13 Inflorescence a head or more diffuse (see below), sometimes subtended by green bracts.
............ ............ ..14 Leaves serrate; corolla bilaterally symmetrical (especially the flowers near the outer edge of the head); inflorescence a head
............ ............ ..14 Leaves entire; corolla radially symmetrical; inflorescence a head or more diffuse (see below).
............ ............ ....15 Petals acute; flowers in terminal panicles, cymes, or panicles, or axillary; plant habit various, not simultaneously with all the characters below
............ ............ ....15 Petals broadly rounded; flowers axillary, solitary; plant a diffusely branched herb with linear leaves
....3 Ovary superior.
............ ............ ......16 Perianth of a single whorl (petals absent) or missing entirely (petals and sepals both absent). {key lead number needs adjusting}
............ ............ ........17 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
............ ............ ........17 Inflorescence not a cyathium (and staminate or bisexual flowers with > 1 stamen, except Callitriche in PLANTAGINACEAE); fresh plants lacking milky juice; fruit various, not as above.
............ ............ ..........18 Flowers 1 (or 2) in leaf axils; leaves entire.
............ ............ ............ 19 Flowers unisexual; sepals 0; flowers (staminate) with 1 stamen
............ ............ ............ 19 Flowers bisexual; sepals 4; flowers with 2, 4, or 6 stamens.
............ ............ ............ ..20 {XXXX}
............ ............ ............ ..20 {YYYY}
............ ............ ..........18 Flowers many, in axillary spikes, cymes, or glomerules, or in terminal spikes, heads, cymes, or panicles; leaves entire or serrate.
............ ............ ............ ....21 Fruit a 2-locular capsule; {XXXX}
............ ............ ............ ....21 Fruit single-seeded, an achene or utricle; {YYYY}.
............ ............ ............ ......22 Leaves serrate, regularly and sharply so; plants with stinging hairs (or not)
............ ............ ............ ......22 Leaves entire, or with a few very obscure crenations (Iresine) or basally disposed rounded lobe-like teeth (Atriplex); plants without stinging hairs.
............ ............ ............ ........23 Leaves of a pair slightly to strongly different in size
............ ............ ............ ........23 Leaves of a pair the same size.
............ ............ ............ ..........24 Styles 1-2 (-3); leaves 2-30 mm long, 0.5-8 mm wide, linear or narrowly elliptic
............ ............ ............ ..........24 Style 1; leaves generally either longer than 30 mm, or wider than 8 mm (if linear and smaller than those dimensions, then fleshy).
............ ............ ............ ............ 25 Tepals scarious; inflorescence of heads, spikes, or panicles
............ ............ ............ ............ 25 Tepals herbaceous; inflorescence of glomerules, these axillary or arrayed in spikes or panicles
............ ............ ......16 Perianth in 2 whorls (sepals and petals both present).
............ ............ ............ ............ ..26 Gynoecium of 4-many pistils, each 1-carpellate.
............ ............ ............ ............ ....27 Pistils 4-5, in a single whorl; stamens 4, 5, 8, or 10; fruit an aggregate of follicles
............ ............ ............ ............ ....27 Pistils many, spiral; stamens many; fruit an aggregate of plumose achenes
............ ............ ............ ............ ..26 Gynoecium either of 1 pistil (with 1 or more carpels), or of 2 pistils, united only by the style and stigma (APOCYNACEAE).
............ ............ ............ ............ ......28 Petals not at all connate, not even at their bases.
............ ............ ............ ............ ........29 Leaves with pellucid punctate glands (most easily visible with transmitted light); stamens often fascicled into 3, 4, or 5 fascicles; petals yellow or pinkish
............ ............ ............ ............ ........29 Leaves lacking pellucid punctate glands; stamens not fascicled; petals variously colored.
............ ............ ............ ............ ..........30 Sepals 2; stamens opposite the petals
............ ............ ............ ............ ..........30 Sepals 3-7; stamens opposite the sepals.
............ ............ ............ ............ ............ 31 Petals 3; sepals 5, dimorphic, the 2 outer sepals narrower than the 3 inner and concave sepals; stamens (3-) 5-15 (-25)
............ ............ ............ ............ ............ 31 Petals 4-7; sepals 4-7, normally monomorphic; stamens 4, 5, 6, 8, 10, or 12 (or sometimes rarely 2 or 3).
............ ............ ............ ............ ............ ..32 Capsule 2-5 (-6) locular; style 1; perianth 4-7-merous; stamens 4, 6, 8, 10, or 12
............ ............ ............ ............ ............ ..32 Capsule either 1-locular of 10-locular; styles 2-5; perianth 4-5-merous; stamens 4, 5, 8, or 10 (or rarely 2 or 3).
............ ............ ............ ............ ............ ....33 Capsule 1-locular, dehiscent apically by teeth or valves; sepals connate into a tube or separate; styles 2-5; perianth 4-5-merous; stamens 4, 5, 8, or 10 (or rarely 2 or 3)
............ ............ ............ ............ ............ ....33 Capsule 10-locular (each of the 5 carpels divided at maturity), septicidal; sepals distinct or nearly so; styles 5, perianth 5-merous; stamens 5
............ ............ ............ ............ ......28 Petals connate at least for a short distance at their bases.
............ ............ ............ ............ ............ ......34 Corolla radially symmetrical (or so slightly bilaterally symmetrical as to be mistakable as radially symmetrical); stamens as many as the corolla lobes (or 1 less in Ruellia in ACANTHACEAE, Buchnera in OROBANCHACEAE, Trichostema in LAMIACEAE, and Verbena in VERBENACEAE); carpels 2 or 3.
............ ............ ............ ............ ............ ........35 Pistils 2, united only by the style and stigma; fruit a schizocarp of 2 1-carpellate follicles (often single by abortion); plant with milky juice when fresh (except Catharanthus); leaves entire
............ ............ ............ ............ ............ ........35 Pistil 1 (of 2-5 fused carpels); fruit either a 2-5-carpellate capsule or of 2 or 4 1-seeded nutlets derived from 2 carpels; plant lacking milky juice; leaves entire or serrate.
............ ............ ............ ............ ............ ..........36 Ovary and capsule 3-5-carpellate; capsule 3- or 1-locular.
............ ............ ............ ............ ............ ............ 37 Sepals 2
............ ............ ............ ............ ............ ............ 37 Sepals 5.
............ ............ ............ ............ ............ ............ ..38 Inflorescence a terminal cyme; corolla salverform, with an elongated and very narrow tube, pink or white; capsule 3-locular
............ ............ ............ ............ ............ ............ ..38 Inflorescence various but not cymose, of terminal or axillary racemes or panicles, or of solitary axillary flowers; corolla connate only at the base, the petals appearing nearly separate (not salverform); capsule 1-locular
............ ............ ............ ............ ............ ..........36 Ovary and capsule 2-carpellate; fruit either a 2-locular capsule or of 2 or 4 1-seeded nutlets derived from 2 carpels.
............ ............ ............ ............ ............ ............ ....39 Stamens 4-12, the same number as the corolla lobes; corolla (and the flower as a whole) strictly radially symmetrical.
............ ............ ............ ............ ............ ............ ......40 Capsule septicidal; corolla white, pink, blue, yellowish white, or greenish white; inflorescence either a terminal or axillary cyme, or a terminal panicle or raceme, or a terminal or axillary cyme reduced to 1 or a few flowers
............ ............ ............ ............ ............ ............ ......40 Capsule loculicidal and also deeply 2-lobed; corolla white, pink, or scarlet with a yellow interior; inflorescence of cymosely arranged spikes
............ ............ ............ ............ ............ ............ ....39 Stamens either 4, 1 fewer than the 5 corolla lobes, or 2 (with 2 staminodes); corolla usually slightly bilaterally symmetrical (the flower as a whole made bilaterally symmetrical by the 2 or 4 stamens).
............ ............ ............ ............ ............ ............ ........41 Leaves entire; corolla tube flaring for all of its length
............ ............ ............ ............ ............ ............ ..........42 Fruit a schizocarp of 4 1-seeded nutlets; inflorescence terminal, of cymes; corolla ca. 5 mm long; leaves prominently 3-veined
............ ............ ............ ............ ............ ............ ..........42 Fruit a capsule; inflorescence axillary, of cymes or clusters (often reduced to a solitary flower); corolla > 12 mm long; leaves with single primary vein
............ ............ ............ ............ ............ ............ ........41 Leaves serrate; corolla salverform, the tube narrow and nearly the same diameter for most of its length; inflorescence a terminal spike, raceme, raceme of racemes, or head.
............ ............ ............ ............ ............ ............ ............ 43 Fruit a 2-locular capsule; stamens inserted near the base of the corolla tube
............ ............ ............ ............ ............ ............ ............ 43 Fruit a schizocarp of 4 mericarps; stamens inserted near or above the middle of the corolla tube
............ ............ ............ ............ ............ ......34 Corolla bilaterally symmetrical (or the corolla 2-lipped but the corolla lobes twisted so as to make the flower asymmetrical); fertile stamens fewer than the corolla lobes (except Plantago in PLANTAGINACEAE, which is equal, with 4 each; a few genera have a 5th, sterile, stamen which is obviously different in form than the 4 fertile stamens) (note that many corollas are bilabiate and the number of corolla lobes, 4 or 5, may be difficult to interpret); carpels 2.
............ ............ ............ ............ ............ ............ ............ ..44 Carpels 2, each carpel slightly to deeply lobed, separating at maturity into 4 half-carpellate units (not separating in Phyla in VERBENACEAE); fruit a schizocarp of 4 mericarps (or 2 nutlets in Phyla in VERBENACEAE).
............ ............ ............ ............ ............ ............ ............ ....45 Inflorescence a thyrse, verticillaster, or terminal cyme, the flowers borne in cymose lateral branches; corolla strongly bilaterally symmetrical (rarely nearly radially symmetrical); stems square in ×-section (or sometimes rounded, especially on older growth); fresh plants often (but not always) aromatic
............ ............ ............ ............ ............ ............ ............ ....45 Inflorescence of spikes, racemes, or heads, the flowers or fruits single at nodes; corolla often nearly radially symmetrical; stems rounded in X-section (rarely square); fresh plants usually not aromatic
............ ............ ............ ............ ............ ............ ............ ..44 Carpels 2, unlobed; fruit a capsule (or an achene in Phryma).
............ ............ ............ ............ ............ ............ ............ ......46 Stamens 2.
............ ............ ............ ............ ............ ............ ............ ........47 Corolla 4 lobed, almost radially symmetrical; corolla scarious, white, or bluish
............ ............ ............ ............ ............ ............ ............ ........47 Corolla 4-5-lobed, either strongly bilabiate or salverform (Pseuderanthemum in ACANTHACEAE); white, blue, or yellow.
............ ............ ............ ............ ............ ............ ............ ..........48 Inflorescence an axillary cluster or spike
............ ............ ............ ............ ............ ............ ............ ..........48 Inflorescence of solitary (rarely 2) axillary flower. {add [Hypoestes] ACANTHACEAE}
............ ............ ............ ............ ............ ............ ............ ............ 49 Sepals 4
............ ............ ............ ............ ............ ............ ............ ............ 49 Sepals 5, distinct or nearly so.
............ ............ ............ ............ ............ ............ ............ ............ ..50 Corolla barely bilaterally symmetrical, the lobes about as long as the tube; outer sepals ovate, much wider than the inner sepals
............ ............ ............ ............ ............ ............ ............ ............ ..50 Corolla distinctly bilabiate, the lobes shorter than the tube; sepals of nearly the same width.
............ ............ ............ ............ ............ ............ ............ ............ ....51 Sterile stamens (the lower pair) consisting of slender filaments
............ ............ ............ ............ ............ ............ ............ ............ ....51 Sterile stamens minute or completely absent
............ ............ ............ ............ ............ ............ ............ ......46 Stamens 4.
............ ............ ............ ............ ............ ............ ............ ............ ......52 Corolla 4 lobed, nearly radially symmetrical; corolla scarious
............ ............ ............ ............ ............ ............ ............ ............ ......52 Corolla 5-lobed, distinctly bilabiate or in some nearly radially symmetrical; corolla colored.
............ ............ ............ ............ ............ ............ ............ ............ ........53 Flowers in terminal racemes, panicles, or spikes, the inflorescence not interspersed with large, leaf-like bracts.
............ ............ ............ ............ ............ ............ ............ ............ ..........54 Sepals separate to the base or nearly so, not forming a tube
............ ............ ............ ............ ............ ............ ............ ............ ..........54 Sepals connate for at least 0.3× their length to form a tube (this cup-like and flaring in Scrophularia in SCROPHULARIACEAE).
............ ............ ............ ............ ............ ............ ............ ............ ............ 55 Inflorescence a diffuse panicle; corolla 5-11 mm long, reddish-brown (sometimes with some yellow); fruit a septicidal capsule
............ ............ ............ ............ ............ ............ ............ ............ ............ 55 Inflorescence of 1 or more terminal (and sometimes upper axillary) spikes or racemes; corolla 10-50 mm long (6-8 mm long in Phryma in PHRYMACEAE), white, pink, blue, purple, or yellow; fruit either a loculicidal capsule (OROBANCHACEAE) or a single seeded achene (Phryma in PHRYMACEAE).
............ ............ ............ ............ ............ ............ ............ ............ ............ ..56 Corolla 10-50 mm long, pink, blue, purple, or yellow; fruit a loculicidal capsule
............ ............ ............ ............ ............ ............ ............ ............ ............ ..56 Corolla 6-8 mm long, white to pale pink; fruit a 1-seeded achene contained in the accrescent calyx, this “lopping down” against the inflorescence axis
............ ............ ............ ............ ............ ............ ............ ............ ........53 Flowers axillary and solitary, borne in the axils of normally-sized leaves or somewhat reduced but still large and leaf-like bracts [some taxa keyed here and below].
............ ............ ............ ............ ............ ............ ............ ............ ............ ....57 Sepals separate to the base or nearly so, not forming a tube.
............ ............ ............ ............ ............ ............ ............ ............ ............ ......58 Corolla distinctly bilabiate
............ ............ ............ ............ ............ ............ ............ ............ ............ ......58 Corolla not bilabiate, only slightly bilaterally symmetrical.
............ ............ ............ ............ ............ ............ ............ ............ ............ ........59 Leaves serrate, 2.0-4.5 cm long; plant usually blackening on drying
............ ............ ............ ............ ............ ............ ............ ............ ............ ........59 Leaves entire, either mostly larger or smaller [see below]; plant not blackening on drying
............ ............ ............ ............ ............ ............ ............ ............ ............ ..........60 Leaves 0.6-2.8 cm long, round, obovate, or broadly elliptic, < 1.8× as long as wide; plants creeping, ascending to 3 dm tall; [plants of wet places]
............ ............ ............ ............ ............ ............ ............ ............ ............ ..........60 Leaves 3-30 cm long, narrowly elliptic to lanceolate, > 2× as long as wide; plants erect or the stems sprawling; [plants mostly of uplands]
............ ............ ............ ............ ............ ............ ............ ............ ............ ....57 Sepals connate for at least 0.3× their length to form a tube.
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ 61 Corolla yellow, orange, or red.
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ..62 Calyx lobes longer than the tube, or as long as the tube, corolla 25-50 mm long; plants usually blackening on drying
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ..62 Calyx lobes shorter than the tube; corolla 14-22 mm long; plants not blackening on drying.
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ....63 Corolla red or orange, with a very narrow, cylindrical tube, the lobes then flaring into a limb about 1 cm across; plants blackening on drying; [rare alien, in crop fields, a noxious hemiparasitic weed under quarantine]
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ....63 Corolla yellow, not narrowly cylindrical, the lower lip arched; plants not blackening on drying; [rare, in seepage wetlands]
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ 61 Corolla white, pale blue, lavender, or pink (sometimes with some yellow).
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ......64 Corolla pink (sometimes almost white), often lined with yellow inside; leaves narrowly linear, often filiform (except lanceolate in A. auriculata); plants usually blackening on drying (some species do not); corolla not strongly bilabiate
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ......64 Corolla white, blue, or combinations of blue and white (sometimes with some yellow markings); leaves broader, mostly lanceolate; plants not blackening on drying; corolla strongly bilabiate.
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ........65 Upper lip of the corolla hooded, enfolding the anthers
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ........65 Upper lip of the corolla not hooded and enclosing the anthers; plants not blackening on drying.
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ..........66 Corolla blue; lower lip of the corolla arched upwards into the throat; plants perennial from rhizomes or crowns, 3-13 dm tall
............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ..........66 Corolla bicolored, the upper lip white or very pale blue, the lower lip bright blue; lower lip of the corolla folded downward into a pouch enfolding the anthers; plants annuals, 0.5-4 dm tall

Key S3: herbaceous dicots with opposite, simple, and pinnately lobed leaves on the stem

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 tightly grouped, but then with other features differing, such as stamens 4, or green calyx present, or fruit a schizocarp of mericarps, etc.).
..2 Flowers tiny, individually inconspicuous; perianth absent or vestigial; fruit a utricle
..2 Flowers larger, individually conspicuous; perianth present, the petals or sepals brightly colored; fruit a capsule (or aggregate of achenes in Clematis in RANUNCULACEAE or schizocarp of 4 mericarps in Glandularia in VERBENACEAE).
....3 Flowers radially symmetrical; stamens 5 or many; fruit a capsule or aggregate of achenes.
......4 Stamens 5; fruit a capsule
......4 Stamens many; fruit an aggregate of plumose achenes
....3 Flowers bilaterally symmetrical (sometimes only slightly so); stamens 4 (or 2 in Veronica in PLANTAGINACEAE); fruit a capsule or schizocarp of mericarps.
........5 Inflorescence of cymosely arranged spikes or heads; fruit a schizocarp of 4 nutlets
........5 Inflorescence of solitary axillary flowers or terminal racemes.
..........6 Corolla yellow, orange, or red; plants often drying black (but not Striga); sepals connate into a tube at least 1/3 as long as the corolla lobes; calyx 5-merous
..........6 Corolla white, pink, lavender, or blue; plants not drying black; sepals distinct or only shortly connate into a short tube, the calyx lobes much longer than the tube; calyx 5- or 4-merous