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Key to Malvaceae

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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.
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  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 Tree; fruit a woody drupe, the peduncle adnate for half of its length to a thin, curved, leafy bract; [subfamily Tilioideae]
             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
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  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
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                                                        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