1 Petals absent (only sepals present, these connate and tubular); carpels 5, whorled, each expanding into a stalked and papery structure which bears 1-4 pea-sized seeds along its margins; tree; leaves 10-40 cm wide, 3-5 lobed, the lobes acute, the margins entire; [subfamily Sterculioideae]

1 Petals present; carpels 1, 5, or many, united or separate, but not as above; tree, shrub, or herb; leaves< 15 cm wide, lobed or unlobed, but if lobed then also serrate.

  2 Epicalyx of bracts absent (no whorl of bract-like structures subtending the calyx in each flower; Malachra inflorescences subtended by boat-shaped bracts, but individual flowers lacking an epicalyx).

    3 Stamens 3 or 5; [subfamily Byttnerioideae].

      4 Flowers solitary or in 2-3-flowered fascicles in leaf axils; petals hooded, caducous; capsules with prickles 0.3-0.5 mm long

      4 Flowers in capitate or umbellate clusters of > 4 flowers; petals flat, persistent; capsules smooth or hairy.

        5 Ovary with 5 carpels and 5 styles; capsule with 5-10 seeds; corolla pink, purple, or white

        5 Ovary with 1 carpel and 1 style; capsule with 1 seed; corolla orange to yellow

    3 Stamens >10.

          6 Stamens free.

             7 Herb or shrub (sometimes a small tree in Grewia); fruit a capsule OR a fleshy drupe lacking a conspicuous leafy bract; [subfamily Grewioideae].

               8 Plants shrubs or small trees; fruit a drupe (purple and somewhat fleshy when ripe); [subfamily Grewioideae, tribe Grewieae].

               8 Plants herbs or shrubs; fruit a capsule [subfamily Grewioideae, tribe Apeibeae].

                 9 Leaves rounded or subcordate at base, acute at apex; fruit much longer than broad, unarmed

                 9 Leaves cuneate at base, acuminate at apex; fruit subglobose, with hooked spines

          6 Stamens united into a staminal column adnate to the corolla at its base; [subfamily Malvoideae; tribe Malveae].

                   10 Inflorescence subtended by (mostly) sessile boat-shaped bracts, these prominently veined and often at least somewhat deltoid or cordate in shape; stems puberulent or hispid (not viscid, but densely stellate in M. capitata)

                   10 Inflorescence not subtended by sessile, boat-shaped bracts; stems glabrous to pubescent (viscid or not).

                     11 Seeds 2 or more per carpel.

                       12 Fruit inflated, papery, mericarps lacking a beak; [s. FL and s. TX in our area]

                       12 Fruit not inflated, mericarps with a beak; [collectively widespread]

                     11 Seed 1 per carpel.

                          13 Leaves palmately and deeply cleft (> 9/10s of the way to the midrib) into linear segments

                          13 Leaves unlobed or lobed (if lobed , < 4/5’s of the way to the midrib and the lobes broad).

                            14 Flowers many in a terminal panicle; corolla white; style branches filiform, the stigmatic surface elongate along the inner side of the branches; leaves >10 cm wide, deeply 5-9-lobed; plants 1-2 m tall

                            14 Flowers solitary or a few in leaf axils (or many in a terminal panicle in Sida hermaphrodita); corolla blue-purple, yellow, or white; style branches truncate, the stigmatic surface terminal and capitate; leaves < 2 cm wide, unlobed (or leaves > 10 cm wide and deeply 3-7-lobed in Sida hermaphrodita); plants < 1 m tall (or 1-4 m tall in Sida hermaphrodita).

                              15 Corolla blue to purple; lateral walls of the carpels disintegrating at maturity of the fruit

                              15 Corolla yellow or white; lateral walls of the carpels persistent

                                16 Leaves deeply palmately lobed; plants 1-2 (-4) m tall; petals white

                                16 Leaves unlobed; plants 0.2-1 m tall; petals yellow

  2 Epicalyx of bracts (immediately subtending the calyx) present.

                                  17 Fruit a loculicidal capsule, or fleshy and berry-like, or leathery and indehiscent.

                                    18 Fruit fleshy and berry-like or leathery and indehiscent; [subfamily Malvoideae].

                                       19 Corolla open at anthesis; involucel bracts 3-5; fruit leathery, indehiscent (appearing almost woody); [tribe Gossypieae]

                                       19 Corolla closed (or nearly so) at anthesis; involucel bracts 7-12; fruit fleshy and berry-like, eventually dehiscing; [tribe Hibisceae]

                                    18 Fruit a loculicidal capsule.

                                         20 Calyx spathe-like, soon falling after anthesis; capsules elongate and long-tipped; [subfamily Malvoideae; tribe Hibisceae]

                                         20 Calyx persistent, radially symmetrical; capsules typically rounded or globose, not long-tipped.

                                           21 Style branches short, erect, and clavate (club-shaped); epicalyx bracts 3, large, foliaceous, and incised (Gossypium) or 6-9 (Cienfuegosia); seeds hairy (inconspicuously so in Cienfuegosia drummondii) or densely wooly with long white fibers (Gossypium); [subfamily Malvoideae; tribe Gossypiae]

                                             22 Plants smaller herbs (sometimes smaller subshrubs, stems rarely exceeding 0.5 m in height), decumbent to erect; seeds 2-4 mm long, inconspicuously (C. drummondii) or conspicuously (C. yucatanensis) hairy; epicalyx bracts 6-9 (if longer, as in C. drummondii, then not concealing the calyx)

                                             22 Plants larger shrubs, 1-2 m tall, stems primarily erect; seeds 8-10 mm long, densely wooly; epicalyx bracts 3 (these large, incised, and often concealing the calyx)

                                           21 Style branches elongate, spreading; epicalyx bracts 5-15, linear to lanceolate and untoothed; seeds sometimes pubescent but not with long white fibers; [subfamily Malvoideae; tribe Hibisceae].

                                               23 Stipules conspicuous, enclosing the twig, early deciduous but the scars forming conspicuous annular rings encircling the stem (usually enclosing the terminal bud); fruit not spiny (but densely pubescent); [non-natives, c. and s. FL]

                                               23 Stipule scars inconspicuous, not forming an annular ring encircling the stem; [natives and non-natives, widespread].

                                                 24 Locules of the fruit several-seeded; capsule longer than broad, the apex pointed or rounded; petals yellow, white, red, or pink (if pink, then > 4 cm long, or the plant a shrub)

                                                 24 Locules of the fruit 1-seeded; capsule depressed-globose, indented at the apex; petals pink, 2-4 cm long

                                  17 Fruit a schizocarp, consiting of radially disposed, 1- to several-seeded, dry carpels that split apart at maturity.

                                                    25 Bracts of the epicalyx 5 or more.

                                                      26 Shrubs or woody herbs, with leaves not basally disposed; flowers in axils of well-developed leaves; fruit spiny (except Pavonia hastata, which usually has puberulent fruit); [of SC southward]; [subfamily Malvoideae; tribe Hibisceae].

                                                        27 Bracts of the epicalyx 5-15, distinct; fruit with 0-3 spines per carpel; leaves lacking foliar nectaries

                                                        27 Bracts of epicalyx 5, fused basally; fruit covered with numerous glochidiate spines; leaves with 1-3 foliar nectaries (glands) on the undersurface (at the base of the central veins)

                                                      26 Herbs, with leaves basally disposed; flowers in terminal bracteates spikes or racemes; fruit lacking spines; [collectively widespread]; [subfamily Malvoideae; tribe Malveae].

                                                          28 Plant 1.5-3 m tall, usually unbranched; flowers 6-10 cm across

                                                          28 Plant 0.5-1.2 m tall, branched; flowers 2-3 cm across

                                                    25 Bracts of the epicalyx 2-3; [subfamily Malvoideae; tribe Malveae].

                                                            29 Ovules and seeds 2 or more per carpel.

                                                              30 Herb 0.5-2.5 m tall, upright; petals 2-3 cm long, pink-purple; carpels not beaked at the tip

                                                              30 Herb to 0.5 m tall, prostrate to ascending; petals 0.3-0.5 cm long, orange-red; carpels beaked at the tip

                                                            29 Ovules and seeds 1 per carpel.

                                                                 31 Leaf blades 1.5-8× as long as wide.

                                                                   32 Style branches filiform, the stigmatic surface elongate along the inner side of the branches

                                                                   32 Style branches truncate, the stigmatic surface terminal and capitate

                                                                 31 Leaf blades orbicular, about as wide as long.

                                                                     33 Leaves deeply palmately cleft

                                                                     33 Leaves unlobed or shallowly lobed

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

                       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 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)