1 Leaves evergreen. {add to 1a: [Conocarpus] COMBRETACEAE; [Maytenus] CELASTRACEAE}

  2 Leaves tiny, scale-like, broadest at the base and more or less clasping the stem, < 10 mm long and < 1 mm wide

  2 Leaves larger and broader, > 40 mm long and > 8 mm wide.

    3 Fruit a hesperidium; petiole flanged or winged for most of its length, constricted at the base of the blade (except linear in C. medica)

    3 Fruit various (but not a hesperidium); petiole linear (not flanged or winged with leafy tissue).

      4 Leaves pubescent with stellate hairs or peltate scales (sometimes hairs simple), or glandular punctate, appearing as translucent dots (best seen on lower leaf surfaces, with at least 10x magnification).

        5 Leaves (fresh) strongly odorous, glandular-punctate (appearing as translucent dots), with strongly parallel venation; bark on medium-aged to mature trees papery and peeling

        5 Leaves (fresh) not strongly fragrant, with stellate hairs or punctate scales, leaf venation various but not strongly parallel, bark various but not papery

          6 Vestiture of the lower leaf surface of silvery and/or reddish peltate scales; plants hermaphroditic, the flowers bisexual; fruit a fleshy drupe

          6 Vestiture of the lower leaf surface in part of stellate hairs (and also of simple acicular hairs and gland-tipped hairs); plants monoecious, the male flowers in yellow to brownish catkins, the female flowers solitary or in small spikes; fruit a nut in a cupule (an acorn)

      4 Leaves glabrous, or if hairy, with strictly simple hairs.

             7 Flowers solitary, terminal, large (> 5 cm in diameter); pistils many, carpels separate; petals many (typically > 8); leaves mostly > 10 cm long (at least some on a branch longer than 10 cm); fruit an aggregate of follicles, each dehiscing along 1 suture; stipule scar circumferential at each node, encircling the twig

             7 Flowers either in axillary racemes, panicles, umbels, fascicles, or solitary, or in terminal corymbs, umbels, compound cymes, or racemes, small (< 5 cm in diameter); pistil 1, with 1-8 fused carpels; petals 3-8; leaves < 30 cm long; fruit either a drupe, berry, or capsule; stipule scars either absent or linear or triangular, not circumferentially encircling the twig.

               8 Inflorescence terminal, a corymb, umbel, compound cyme, or raceme; fruit either a capsule (dehiscing along 5 longitudinal sutures) or a few-seeded berry.

                 9 Inflorescence a compound cyme; petals deep red to magenta; fruit a few-seeded drupe

                 9 Inflorescence a corymb, umbel, or raceme; petals white or pink; fruit a capsule, opening by 5 longitudinal sutures.

                   10 Capsules ovoid to globose or subglobose, about as long as broad, 5-8 mm long; leaves 5-12 cm long, 2-3× as long as wide

                   10 Capsules elongate, > 2× as long as broad, 8-18 mm long; leaves 10-30 cm long, 3-5× as long as wide

               8 Inflorescence axillary, a raceme, panicle, umbel, fascicle, or solitary; fruit drupaceous, fleshy to dry, but not regularly dehiscent along sutures.

                     11 Flowers solitary, axillary or superaxillary; perianth somewhat fleshy, in whorls of 3; carpels numerous, partly fused; fruit an aggregate syncarp

                     11 Flowers in inflorescences of > 2 flowers; perianth not fleshy, in whorls of 4 or 5 (or 3 in Lauraceae); carpels 2, 3, 4, or 5, fused; fruit a capsule, drupe, or berry

                       12 Inflorescence an axillary raceme (with an elongate central axis, to which all flowers/fruits are attached).

                          13 Fruit a dry, tan to brown, spherical or winged drupe; stamens 5 or 10; carpels 2-5; leaves oblanceolate (rarely narrowly elliptic), < 2.5 cm wide, the apex obtuse (more rarely acute, retuse, or rounded)

                          13 Fruit a fleshy, black, spherical drupe; stamens 10; carpels 1; leaves elliptic, the apex acute to short-acuminate

                       12 Inflorescence either an axillary umbel or fascicle (or reduced to solitary) or an axillary compound inflorescence (panicle or compound cyme), with 2-3 orders of branching.

                            14 Fruit a fleshy and oily 1-seeded drupe; flowers 3-merous, with separate and undifferentiated perianth segments; fresh plants strongly aromatic; inflorescence compound, a panicle or compound cyme (with 2-3 orders of branching); [Basal Angiosperms]

                            14 Fruit a fleshy but not oily 1-8-seeded drupe or berry; flowers 4-8-merous, with differentiated sepals and petals, the petals usually basally fused; fresh plants not strongly aromatic; inflorescence an axillary umbel or fascicle (or reduced to solitary), a central axis absent or < 1 cm long; [Eudicots].

                              15 Plants unarmed (or with marginal leaf prickles or spines); stamens 4-7, not epipetalous; fruit a drupe with 4-8 pyrenes;flowers 4-7-merous

                              15 Plants armed with nodal thorns; stamens 5 and staminodia 5, epipetalous; fruit a berry or drupe with 1 seed;flowers 5-merous

1 Leaves deciduous.

                                16 Leaf base deeply to shallowly cordate, with 3-7 palmate veins from the base; leaf blade about as wide as long or a little longer, mostly 0.9-1.3× as long as wide.

                                  17 Juncture of petiole and leaf blade with 2 red glands; corolla radially symmetrical, with 5-8 petals, white with red veins towards the base of the petals; flowers unisexual; fruit globose, 4-8 cm in diameter; main palmate leaf veins 3 (-5)

                                  17 Juncture of petiole and leaf blade eglandular, but the uppermost 1-3 mm of the petiole swollen into a prominent upper pulvinus; corolla bilaterally symmetrical, with 5 petals, pink to purple (rarely white in some cultivars); flowers bisexual; fruit an oblong, flat legume, 6-10 cm long; main palmate leaf veins 5-7 (-9)

                                16 Leaf base cuneate, rounded, truncate, subcordate, or auriculate (with 2 small “earlobe-like” lobes at the base of the leaf blade), with 1 (mid) vein from the base (3 veins from the base in Celtis in CANNABACEAE); leaf blade about as wide as long, or somewhat to much longer, 0.9-10× as long as wide.

                                    18 Leaves 0.9-1.4× as long as wide (some taxa keyed in both leads).

                                       19 Stipule scars circumferential, forming a line around the twig; flowers and aggregate fruits solitary, terminal; [Basal Angiosperms]

                                       19 Stipule scars not circumferential (or not apparent); flowers and simple fruits in inflorescences of 1-many flowers, axillary or terminal, but not simultaneously solitary and terminal; [Eudicots].

                                         20 Leaf blade 3-6 cm long, 1-1.5× as long as the flexuous petiole

                                         20 Leaf blade 4-30 cm long, > 3× as long as the stiff petiole.

                                           21 Petioles 1-5 (or more) cm long; leaves broadly orbicular, rounded at the base, usually rounded (rarely obtuse or nearly acute) at the apex, entire; hairs on foliage simple or absent; fruit a fleshy drupe

                                           21 Petioles < 1 cm long; leaves various in shape, often acuminate at the apex and/or cuneate at the base, often with some tendency to toothing; hairs on foliage stellate (use at least 10× magnification), at least in part; fruit either a nut borne in a cup (acorn) or a dry, subglobose 3-valved capsule, with 1 seed.

                                             22 Fruit a nut in a cupule (an acorn); flowers unisexual, greenish or brownish, individually inconspicuous, the male flowers borne in catkins

                                             22 Fruit a dry, subglobose 3-valved capsule, with 1 seed; flowers bisexual, white, conspicuous

                                    18 Leaves > 1.4× as long as wide.

                                               23 Leaves densely covered with silvery peltate scales (use 10× or greater magnification), giving the leaf blade surface a metallic appearance

                                               23 Leaves glabrous, glabrescent or variously pubescent (including densely and silkily so, giving the leaf surface a shiny appearance), but not as above.

                                                 24 Plants bearing nodal thorns; leaves elliptic to obovate, 3-9 cm long, 1-4 cm wide, 1.5-4× as long as wide.

                                                    25 Sap clear, not viscous; sepals 4; petals 4, densely long-hairy on their upper (inner) side); fruit a yellow, 1-seeded drupe, 20-30 mm long; [FL southward]

                                                    25 Sap milky or nearly clear but thick and sticky; sepals 5; petals 5, not densely long-hairy; fruit a black, 5-seeded berry, 5-15 mm long; [widespread in our area]

                                                 24 Plants unarmed (except spiny in Maclura in MORACEAE); leaves various in shape, from broadest towards the base, near the middle, or towards the apex, 3-80 cm long, 1-30 cm wide, 1.5-10× as long as wide.

                                                      26 Leaves distinctly widest near the base (at a point < 0.3× of the way from the base of the leaf blade to its apex), gradually long-tapering to an acuminate apex.

                                                        27 Fruit a spherical, dry drupe, 4-8 mm in diameter, with a single seed; leaf 1.5-6 cm wide

                                                        27 Fruit a spherical, fleshy multiple, 80-120 mm in diameter; leaf 5-8 cm wide

                                                      26 Leaves widest near the middle or towards the tip of the leaf blade (at a point > 0.4× of the way from the base of the leaf blade to its apex).

                                                          28 Pubescence of the foliage stellate (at least in part; simple hairs sometimes present as well); flowers unisexual, the individual flowers inconspicuous, male flowers in catkins; fruit a nut in a cupule (an acorn)

                                                          28 Pubescence of the foliage simple or absent (except stellate in STYRACACEAE); flowers bisexual, conspicuous, borne variously, but not in catkins (except in Leitneria); fruit various.

                                                            29 Leaf undersurface strongly whitened

                                                            29 Leaf surface green (often somewhat paler green than the upper surface, but not whitened).

                                                              30 Flowers unisexual and borne in male and female catkins; plants dioecious

                                                              30 Flowers bisexual, not borne in catkins; plants hermaphroditic.

                                                                 31 Flowers solitary; ovary superior; perianth either 3-merous and whorled or many-merous and spiraled; leaves mostly > 20 cm long and > 8 cm wide, distinctly broadest towards the apex (> 0.6× of the way from the leaf blade base to apex) (except Magnolia acuminata, which is sometimes both shorter, narrower, and broadest near the middle or towards the base); [Basal Angiosperms].

                                                                   32 Flowers axillary, < 2 cm across, brown or maroon; perianth 3-merous, whorled; fresh foliage with a strong musky odor; fruit a fleshy berry; leaves cuneate at the base; twigs lacking circumferential stipule scars at each node

                                                                   32 Flowers terminal, > 4 cm across, white, pale yellow, or pink; perianth many-merous, spiraled; fresh foliage not noticeably aromatic; fruit an aggregate of follicles; leaves cuneate or auriculate at the base; twigs with circumferential stipule scars at each node

                                                                 31 Flowers in inflorescences of several to many; ovary inferior (or superior in Diospyros in EBENACEAE and Cyrilla in CYRILLACEAE); perianth 4-5-merous; leaves mostly < 20 cm long and < 10 cm wide, broadest near the middle or towards the apex; [Eudicots].

                                                                     33 Leaves with prominently parallel-arcing secondary veins; inflorescence a terminal corymb; leaves clustered at the tips of the twigs, thus appearing pseudo-whorled; trichomes of the leaf undersurface predominantly 2-branched (some simple) (use at least 10× magnification); flowers 4-merous; fruit a blue drupe; small tree

                                                                     33 Leaves with secondary veins more obscure and complexly branching into tertiary veins; inflorescence axillary (often on the previous year’s wood), solitary to variously fascicled, clustered, or in racemes; leaves arrayed distichously along horizontal or arching twigs, not prominently clustered or pseudo-whorled (except often in Cyrilla in CYRILLACEAE, Symplocos in SYMPLOCACEAE, and Nyssa in NYSSACEAE); trichomes of the leaf undersurface either simple or stellate (or absent); flowers 4-5-merous; fruit a green, blue, or black drupe, an orange berry, or a green to brownish indehiscent capsule; small to large tree.

                                                                       34 Pubescence of foliage and other parts simple; petals either 0, or 4-5 and pink, white, or greenish-yellow, or 10 and greenish-yellow; fruit either a somewhat to very fleshy drupe or berry or a dry, brownish, spherical drupe, 2-2.5 mm in diameter.

                                                                         35 Leaves < 2.5 cm wide, dark green above, somewhat thickened, and tardily deciduous or semi-evergreen; fruit a dry, brownish, spherical drupe, 2-2.5 mm in diameter; inflorescence a narrowly cylindrical raceme with > 40 flowers

                                                                         35 Leaves > 2.5 cm wide, usually medium-green above, herbaceous in texture, promptly seasonally deciduous; fruit a somewhat to very fleshy drupe or berry, > 5 mm in diameter; inflorescence a solitary flower or cluster, head, or irregular raceme of < 15 flowers.

                                                                           36 Fruit a drupe (green when ripe), cylindrical to barrel-shaped, 8-12 mm long; leaves rather thick and leathery in texture, persistent into the winter, dropping tardily or at latest the following spring; flowers bisexual; stamens 30-50, in 5 fascicles

                                                                           36 Fruit a berry (orange when ripe) or a drupe (blue-black, yellow, orange, or red when ripe), 8-50 mm long, spherical or ovoid to ellipsoid; leaves thin in texture, promptly deciduous in the autumn; flowers functionally unisexual; stamens 5-16, separate.

                                                                              37 Fruit a spherical berry, 15-50 mm long, orange when ripe, subtended by the enlarged and persistent woody or leathery calyx; vascular bundles 1 per leaf scar; leaves never toothed; leaves whitish-green beneath; leaf midrib and upper petiole with tiny glands on their upper surfaces (reddish initially, then darkening) (use at least 10× magnification); leaves glabrate to tomentose with curly hairs beneath; female and male flowers on separate trees (dioecious); stamens 16; widest point of the leaf usually at the middle or below, the apex acute to acuminate

                                                                              37 Fruit an ovoid or ellipsoid drupe, 8-30 -40 mm long, blue-black, yellow, orange, or red when ripe; vascular bundles 3 per leaf scar; leaves sometimes bearing a few irregular teeth; leaves pale to medium green beneath; leaf midrib and upper petiole lacking reddish to dark glands on their upper surfaces; leaves glabrous or glabrate beneath; female and male flowers on the same tree (monoecious); stamens 5-12; widest point of the leaf usually beyond or at the middle, the apex obtuse to strikingly and abruptly acuminate

1 Leaves evergreen.

  2 Petiole flanged or winged, constricted at the base of the blade; fruit a hesperidium

  2 Petiole linear (not flanged or winged with leafy tissue); fruit various. {add to 2b: [Sapium] EUPHORBIACEAE, [Photinia] ROSACEAE, [Prunus (caroliniana)] ROSACEAE, [Ilex (cassine, myrtifolia)] AQUIFOLIACEAE}

    3 Leaves 7-20 cm long, usually at least some on a branch > 12 cm long, thick in texture but readily flexible when fresh.

      4 Inflorescence of a solitary flower, axillary, 5-7 cm across; fruit a capsule, ca. 1 cm in diameter

      4 Incflorescence a corymb of many, smaller flowers; fruit a pome, 0.4-0.8 (-1.2) cm in diameter

    3 Leaves 3-12 cm long, thick in texture and also noticeably stiff.

        5 Leaf with a spinose margin, the marginal spines well-developed, generally arrayed along most of the leaf margin and borne at nearly a right angle to the midvein

        5 Leaf margins serrate with one or a few stiff teeth (sometimes sharpish, but not spines), these usually towards the apex of the leaf and oriented towards the leaf apex

1 Leaves deciduous.

          6 Secondary veins neatly pinnate, the veins on each side of the midrib evenly spaced, parallel to one another, and extending nearly or actually to the leaf margin; fruit either a 1-seeded nut (dry, with or without samaroid wings, bracts, a subtending cupule, or an enclosing and valvate involucre) or a fleshy drupe with 2-4 stones.

             7 Leaves doubly-serrate, the number of teeth greater than the number of the pinnate secondary veins (sometimes obscurely so in Planera in ULMACEAE); fruit a nut or samaroid nut, lacking a cupule or valvate involucre, though sometimes associated with green, leaf-like bracts.

               8 Flowers unisexual, in catkins, the tree monoecious; leaf base symmetrical

               8 Flowers bisexual, in axillary fascicles, the tree androgynous; leaf base strongly asymmetrical (oblique) or nearly or quite symmetrical.

             7 Leaves singly serrate or crenate, the teeth the same number as the secondary veins; fruit either a fleshy drupe with 2-4 stones, or a nut with a cupule (acorn) or enclosed by a valvate involucre that splits at maturity.

                 9 Fruit a fleshy drupe with 2-4 stones

                 9 Fruit dry, single-seeded (or with 1-4 nuts in Castanea).

                   10 Fruit > 9 mm long or wide, either a nut with a cupule (acorn) or 1-4 nuts enclosed by a valvate involucre that splits at maturity

                   10 Fruit < 9 mm long and wide, leathery, indehiscent, winged or not

          6 Secondary veins not as above, usually arching and/or branching or reticulating well before reaching the leaf margin; fruit various.

                     11 Leaves strongly 3-5-veined from the base; leaf blade cordate or truncate, often oblique.

                       12 Inflorescence terminal, a compound cyme; peduncles and pedicels becoming swollen, fleshy, and juicy at maturity; [plant rarely naturalized]

                       12 Inflorescence axillary, a solitary flower, a fascicle or cluster, or a cyme; peduncles and pedicels remaining stalk-like; [collectively widespread and common].

                          13 Flowers unisexual, plants monoecious; pith of mature twigs chambered with hollow sections between soft partitions

                          13 Flowers bisexual; plants hermaphroditic; pith of mature twigs continuous without hollow sections between partitions.

                            14 Flowers bisexual; inflorescence an axillary cyme; fresh leaves and stems lacking white latex; fruit simple, a 1-seeded nut; main leaf veins splitting several times towards the leaf margin and leading into the teeth without rejoining and forming a marginal vein; basal veins 5, palmate, all joining together at the summit of the petiole; main lateral leaf veins (above the basal veins) often opposite; winter buds with 3 entire bud scales (1 much smaller than the other 2)

                            14 Flowers unisexual, the pistillate inflorescence a head, the staminate inflorescence a catkin, borne on the same tree (monoecious) or on separate trees (dioecious); fresh leaves and stems with white latex; fruit a multiple of fleshy achenes; main leaf veins splitting towards the margin but then rejoining to form a prominent, looping (scalloped) marginal vein; basal veins 3, palmate, sometimes an additional prominent vein on each side joining the lateral vein above its divergence from the petiole end; main lateral leaf veins (above the basal veins) mainly alternate; winter buds with 5 ciliate-margined bud scales

                     11 Leaves pinnately veined; leaf blade base cordate, subcordate, truncate, rounded, or cuneate base, not oblique.

                              15 Inflorescence a terminal raceme of racemes, with more than 50 flowers; petals connate, urceolate; fruit a 5-valved capsule, < 6 mm in diameter; fresh leaves with a sour taste

                              15 Inflorescence various, either with < 30 flowers or if with > 50 flowers a catkin (with a single axis); corolla with separate petals (or petals absent); fruit various, fleshy or dry, if a 5-valved capsule (Franklinia in THEACEAE), then 15-20 mm in diameter; fresh leaves without a sour taste.

                                16 Pubescence simple (or absent).

                                  17 Flowers very large and showy, 7-9 cm across; fruit a subglobose capsule 1.5-2 cm in diameter

                                  17 Flowers less than 2 cm across; fruit either fleshy and indehiscent, a drupe, samara, or pome, or dry and dehiscent, an ovoid or lanceolate capsule < 0.7 cm in diameter.

                                    18 Flowers unisexual, borne either in axillary catkins; trees dioecious; fruit either dehiscent, a lanceoloid or ovoid capsule (SALICACEAE) or indehiscent, a samara (Eucommia ulmoides).

                                       19 Plants bearing latex; fruit a samara, 25-32 mm long, the apex emarginate

                                       19 Plants not bearing latex; fruit a lanceoloid or ovoid capsule

                                    18 flowers bisexual (unisexual in Ilex in AQUIFOLIACEAE), borne variously in terminal or axillary clusters, cymes, racemes, or umbels, but not at all catkin-like; trees hermaphroditic (dioecious in AQUIFOLIACEAE); fruit indehiscent, a fleshy drupe or pome with 1-many seeds.

                                         20 Pith of twigs with transverse diaphragms and also continuous between the diaphragms (make a longitudinal section of twig and use at least 10× magnification; look for translucent diaphragms spaced at < 1 mm apart, with whiter pith tissue between them); fruit distinctly longer than broad, a 1-seeded drupe

                                         20 Pith of twigs lacking diaphragms, continuous and homogeneous; fruit either suborbicular to spherical or pear-shaped, either a several- to many-seeded pome, or a berry-like drupe with 4-8 seeds, or a 1-seeded drupe.

                                           21 Vascular bundle scars 1 in each leaf scar; fruit a berrylike drupe with 4-8 bony pyrenes; ovary superior, the calyx persistent at the base of the fruit

                                           21 Vascular bundle scars (2-) 3 in each leaf scar; fruit a pome or 1-seeded drupe; ovary either inferior and the calyx persistent at the summit of the fruit (Amelanchier, Crataegus, Malus, Pyrus) or superior and the calyx not at all persistent at the base of the fruit (Prunus)