1 Petals absent; 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 (immediately subtending the calyx) absent.

....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; fruit a capsule; [subfamily Grewioideae, tribe Apeibeae].

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

............ ..8 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].

............ ....9 Seeds 2 or more per carpel

............ ....9 Seed 1 per carpel.

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

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

............ ........11 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

............ ........11 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).

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

............ ..........12 Corolla yellow or white; lateral walls of the carpels persistent

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

............ ............ 13 Leaves unlobed; plants 0.2-1 m tall; petals yellow

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

............ ............ ..14 Fruit a loculicidal capsule or fleshy and berry-like.

............ ............ ....15 Fruit fleshy and berry-like; [subfamily Malvoideae; tribe Hibisceae]

............ ............ ....15 Fruit a loculicidal capsule.

............ ............ ......16 Calyx spathe-like, soon falling after anthesis; [subfamily Malvoideae; tribe Hibisceae]

............ ............ ......16 Calyx radially symmetrical, 5-lobed.

............ ............ ........17 Style branches short, erect, the stigmas nearly sessile; epicalyx bracts 3, large, foliaceous, and incised; seeds bearing long white fibers; [subfamily Malvoideae; tribe Gossypiae]

............ ............ ........17 Style branches elongate, spreading; epicalyx bracts 6-15, linear to lanceolate and untoothed; seeds sometimes pubescent but not with long white fibers; [subfamily Malvoideae; tribe Hibisceae].

............ ............ ..........18 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)

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

............ ............ ..14 Fruit of radially disposed, 1- to several-seeded, dry carpels that split apart at maturity.

............ ............ ............ 19 Bracts of the epicalyx 5 or more.

............ ............ ............ ..20 Shrubs or woody herbs, with leaves not basally disposed; flowers in axils of well-developed leaves; fruit spiny (or lacking spines in Pavonia hastata); [of SC southward]; [subfamily Malvoideae; tribe Hibisceae].

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

............ ............ ............ ....21 Bracts of epicalyx 5, fused basally; fruit covered with numerous glochidiate spines; leaves with 1-3 foliar nectaries (glands) on undersurface near base

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

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

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

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

............ ............ ............ ........23 Ovules and seeds 2 or more per carpel.

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

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

............ ............ ............ ........23 Ovules and seeds 1 per carpel.

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

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

............ ............ ............ ............ ..26 Style branches truncate, the stigmatic surface terminal and capitate

............ ............ ............ ............ 25 Leaf blades orbicular, about as wide as long.

............ ............ ............ ............ ....27 Leaves deeply palmately cleft

............ ............ ............ ............ ....27 Leaves unlobed or shallowly lobed

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

............ ............ ......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)