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Key to Malvaceae

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.
  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
             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
          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)
                       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]
                          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
  2 Epicalyx of bracts (immediately subtending the calyx) present.
                                       19 Corolla closed (or nearly so) at anthesis; involucel bracts 7-12; fruit fleshy and berry-like, eventually dehiscing; [tribe Hibisceae]
                                         20 Calyx spathe-like, soon falling after anthesis; capsules elongate and long-tipped; [subfamily Malvoideae; tribe Hibisceae]
                                           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)
                                  17 Fruit a schizocarp, consiting of radially disposed, 1- to several-seeded, dry carpels that split apart at maturity.
                                                      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 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].