1 Subshrubs or dwarf shrubs, aboveground stems creeping or erect, < 15 cm tall; leaves evergreen.

  2 Leaves 1.5-3 cm wide, coarsely toothed; flowers lacking sepals and petals; [exotic species, sparingly naturalized or spreading in suburban situations]

  2 Leaves < 1.5 cm wide, finely toothed or entire; flowers with sepals and petals; [native species, collectively widespread and common].

    3 Leaves fleshy, terete in ×-section; petals 5, bright pink

    3 Leaves flat, not fleshy; petals white or pale pink.

      4 Leaves < 2.5 mm wide; corolla with petals distinct; plant creeping

      4 Leaves > 5 mm wide; corolla with petals fused (distinct in Chimaphila); plant creeping or erect

1 Shrubs, aboveground stems erect, > 30 cm tall; leaves evergreen or deciduous.

        5 Inflorescence an involucrate (composite) 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

        5 Inflorescence, flower, and fruit structure various, but not with the combination of features as above.

          6 Leaves evergreen.

             7 Leaves glandular-punctate on one or both surfaces with golden-yellow glands; flowers unisexual, lacking a perianth (arranged in axillary catkins); fruit a pale gray, waxy drupe with a single seed

             7 Leaves not glandular punctate; flowers bisexual or unisexual, with a white, pink, or yellow perianth; fruit various: a red, blue, or black drupe, a berry with several seeds, or a capsule.

               8 Petals connate, flowers urceolate (ERICACEAE) or rotate, white to pale pink; flowers bisexual; fruit a drupe (Ehretia in EHRETIACEAE), OR a capsule or berry (ERICACEAE)

                 9 Flowers rotate, fragrant, the petals white, arranged primarily in terminal cymes; fruit an orange or yellow drupe, each bearing 2 hemispheric nutlets (these each also composed of 2 seeds, thus the fruit bearing 4 seeds)

                 9 Flowers urceolate, fragrant or not, the petals white to pale pink, variously arranged in terminal or axillary inflorescences (occasionally solitary in axils); fruit either a capsule or a red, blue, or black berry

               8 Petals distinct, yellow or white; flowers unisexual or bisexual; fruit either a black or red drupe with several pyrenes, a red berry with several seeds, or red or black pomes.

                   10 Plants with nodal, simple or tripartite thorns; flowers bisexual, with a yellow perianth; fruit a red berry with several seeds

                   10 Plants lacking thorns; flowers unisexual or bisexual, with a white perianth (yellow or red in Ochna); fruit either a black or red drupe with several pyrenes or a red or black pome.

                     11 Petals yellow, clawed; sepals red and forming a persistent red receptacle (torus) bearing numerous blackened drupes.

                     11 Petals white, not clawed; sepals not bright red nor persistent, the fruit a drupe or pome.

                       12 Flowers unisexual; fruit a black or red drupe with several pyrenes

                       12 Flowers bisexual; fruit a red or black pome

          6 Leaves deciduous.

                          13 Plants with nodal, simple or tripartite thorns; leaf teeth spinulose

                          13 Plants lacking thorns; leaf teeth acute, blunt, rounded, or callus-tipped, but not spinulose.

                            14 Leaf blade bases conspicuously oblique-cordate or angled-truncate.

                              15 Leaves crenate-wavy, with 1-2 teeth per cm of leaf margin; pubescence of leaves and stems stellate

                              15 Leaves crenate or serrate, but usually not wavy, pubescence of leaves and stems simple

                            14 Leaves crenulate, serrate or serrulate, with >2 teeth per cm of leaf margin; leaves cuneate, rounded, or subcordate at base, not oblique; pubescence of leaves and stems absent or simple.

                                16 Leaves prominently 3-veined from the base.

                                  17 Ovary 5-locular; stamens many or 5, fused or separate; fruit a 5-valved capsule or of 5 mericarps; flowers yellow or pink, or white with a pink blaze

                                  17 Ovary 3-locular; stamens 5, separate; fruit a 3-valved capsule or drupe; flowers white or pale green

                                16 Leaves pinnately veined.

                                    18 Flowers in catkins; perianth absent or very small; fruit a 1-seeded nut, samara, or waxy drupe (capsule in Salix in SALICACEAE).

                                       19 Leaves < 3 cm wide, either punctate-glandular on one or both surfaces or lacking punctate glands; fruit a 1-seeded waxy drupe or a capsule.

                                         20 Leaves punctate-glandular on one or both surfaces; fruit a 1-seeded waxy drupe.

                                         20 Leaves lacking punctate glands; fruit a capsule.

                                    18 Flowers arrayed variously, but not in catkins; perianth present, conspicuous; fruit a 1-many-seeded capsule, pome, berry, or follicle.

                                           21 Ovary inferior; fruit fleshy and indehiscent, a berry or pome.

                                             22 Fruit a berry; leaves lacking stipules

                                             22 Fruit a pome; leaves usually prominently stipular

                                           21 Ovary superior; fruit either dry and dehiscent, a capsule or an aggregate of follicles or achenes, or fleshy and indehiscent, a drupe with 4-8 pyrenes.

                                               23 Flower apocarpous; fruit an aggregate of follicles or achenes

                                               23 Flower syncarpous; fruit either a capsule or a fleshy drupe.

                                                 24 Ovary 1-carpellate; fruit a 1-seeded drupe

                                                 24 Ovary 2-8-carpellate; fruit either a capsule or a drupe with 4-8 pyrenes

                                                    25 Ovary 2-8-locular; fruit fleshy and indehiscent, a drupe with 2-8 pyrenes; flowers mostly functionally unisexual (or sometimes bisexual in RHAMNACEAE).

                                                      26 Petals connate at the base; stamens alternate to the petals and opposite to the sepals; fruit 4-8-locular, with 4-8 pyrenes

                                                      26 Petals separate (or absent in Rhamnus alnifolia); stamens opposite to the petals (when present) and alternate to the sepals; fruit 2-4-locular, with 2-4 pyrenes

                                                    25 Ovary 2-3- or 5-locular; fruit dry and dehiscent, a capsule; flowers bisexual (except Stillingia in EUPHORBIACEAE).

                                                        27 Ovary and capsule 5-locular; stamens 10-many.

                                                          28 Stamens 10; corolla urceolate, sympetalous

                                                          28 Stamens many; corolla spreading, apopetalous

                                                        27 Ovary and capsule 2-3-locular; stamens 2, 5, or 10.

                                                            29 Leaves > 5× as long as wide; stamens 2; ovary and capsule 3-locular; [plants of the Coastal Plain of SC, GA, AL, and FL]

                                                            29 Leaves < 3× as long as wide; stamens 5 or 10; ovary and capsule 2-3-locular; [plants collectively widespread].

                                                              30 Stamens 5; ovary and capsule 2-locular; leaves elliptic (widest near the middle), the teeth fine (usually > 5 points per cm of margin), and along much of the margin; inflorescence a terminal raceme; hairs of the lower leaf surface simple, erect

                                                              30 Stamens 10; ovary and capsule 3-locular; leaves obovate (widest towards the apex), the teeth obscure to coarse (usually < 4 points per cm of margin), and primarily in the upper half of the leaf; inflorescence a terminal or axillary raceme or cyme; hairs of the lower leaf surface either simple and appressed, or stellate.

                                                                 31 Leaf margins regularly and evenly serrate in the upper half of the leaf (usually nearly entire towards the base); inflorescence an elongate, many flowered (>30) raceme borne at the end of branchlets of the season; corolla of separate petals, the stamens separate; hairs of the lower leaf surface simple and appressed

                                                                 31 Leaf margins wavy or irregularly dentate, mainly in the upper half of the leaf; inflorescence a few flowered (<20) axillary raceme, cyme, or cluster; corolla fused basally into a tube, the stamens adnate to the tube; hairs of the lower leaf surface stellate

1 Leaves evergreen.

  2 Petiole flanged or winged (except C. reticulata, which sometimes lacks wings entirely), constricted at the base of the blade; fruit a hesperidium

  2 Petiole linear (not flanged or winged with leafy tissue); fruit various.

    3 Inflorescence a thin (superficially spike-like) thyrse; leaves linear-lanceolate, the petiole apex bearing 2 glands; seeds with a red aril; [waif, Escambia County, FL]

    3 Inflorescence various, not a thyrse (if thin, then flowers arranged in catkins in FAGACEAE); leaves variously lanceolate, elliptic to ovate or rounded, the petiole apex not bearing 2 glands; seeds not bearing red arils; [widespread natives and non-natives]

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

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

        5 Incflorescence a corymb or cyme of many, smaller flowers; fruit a pome, 0.4-0.8 (-1.2) cm in diameter (Photinia) or a drupe of similar size (Ehretia).

          6 Fruit an orange to yellow drupe, ultimately containing 4 seeds (from 2 paired nutlets); inflorescence a cyme

          6 Fruit a pome; inflorescence a corymb

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

             7 Leaves somewhat 2-ranked (subdistichous), the bases of the blades usually oblique; flowers yellowish-green, occasionally present on the trunks (plants cauliflorous), the trunks smooth and white, sometimes fluted (with irregular vertical ridges, at least on larger plants); [c. and s. FL only in our flora area]

             7 Leaves subdistichous or not, the bases of the blades not oblique; flowers variously colored (usually white in Ilex and Ehretia, brownish-white and apetalous in Fagaceae); plants never cauliflorous, the trunks smooth or with thickened ridges, rarely fluted.

               8 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; flowers not catkins, bearing petals; fruit berrylike, usually at least somewhat fleshy

               8 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 somewhat ascendant; flowers catkins and apetalous (FAGACEAE) or bearing petals (Ehretia in EHRETIACEAE); fruit an acorn (not fleshy) or a drupe (somewhat fleshy).

                 9 Flowers bearing petals, arranged in cymes; fruit a drupe, usually at least somewhat fleshy

                 9 Flowers catkins, apetalous; fruit an acorn, not fleshy

1 Leaves deciduous.

                   10 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.

                     11 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.

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

                     11 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.

                          13 Fruit a fleshy drupe with 2-4 stones

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

                            14 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

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

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

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

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

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

                                  17 Flowers unisexual, plants monoecious; bark on mature trees usually warty or with corky fissures; pith of mature twigs chambered with hollow sections between soft partitions (Celtis) or solid (Trema).

                                    18 Leaf blades entire or irregularly serrate (the margins usually with at least some portions entire, even if minimal), the lower surfaces glabrous or nearly so; cymes few-flowered (at least pistillate); [collectively widespread]

                                    18 Leaf blade margins uniformly serrate or crenate throughout (the teeth uniform and without some portions entire), the lower surfaces pubescent; flowers many (12-20), arranged in dense axillary cymes; [FL and s. TX only in our area]

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

                                       19 Flowers white, showy, and often singular (the petals 12-20 mm long); fruit a red berry 10-15 mm in diameter; [uncommon non-native, s. FL]

                                       19 Flowers either smaller yellowish-white cymes (Tilia) or unisexual pistillate heads or staminate catkins (Moraceae); fruit either nutlike and bearing a curved bract (Tilia) or a fleshy syncarp (Moraceae); [widespread native and non-natives]

                                         20 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)

                                         20 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

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

                                           21 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

                                           21 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.

                                             22 Pubescence stellate (look especially in vein axils on the undersurface of the leaf)

                                             22 Pubescence simple (or absent).

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

                                               23 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.

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

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

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

                                                 24 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.

                                                      26 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

                                                      26 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.

                                                        27 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

                                                        27 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)