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Key to Rutaceae

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1 Herbs, becoming somewhat woody at the base, < 1 (exceptionally to 1.4) m tall; [subfamily Rutoideae].
  2 Leaves 2-pinnatifid, with many segments; [exotic, grown horticulturally, scattered as persistent or weakly naturalized]
  2 Leaves simple; [native in calcareous grasslands and woodlands in ne. and c. TX westwards and southwards]
1 Shrubs and trees, definitely woody, > 1 m tall when mature (flowering and fruiting).
    3 Leaves either simple, or unifoliolate and appearing simple.
      4 Stems unarmed, inflorescence axes and young stems with short, red-brown, scurfy hairs; inflorescences of short, compact to somewhat elongate racemes; [subfamily Aurantioideae; Bergera alliance]
      4 Stems armed or unarmed, inflorescences and young stems glabrous, or pubescent with short, grey to white, erect to curved hairs; inflorescences of small fascicles, or solitary or paired flowers; [subfamily Aurantioideae; Citrus alliance].
        5 Hesperidia bluish black when ripe, 0.8-1.2 cm in diameter; stamens 10; petiole not winged; stems armed; abaxial leaf surface with raised lateral veins; petals < 0.5 cm long
        5 Hesperidia green, yellow, or orange when ripe, > 1.5 cm in diameter; stamens 20+; petiole usually winged; stems armed or unarmed; abaxial leaf surface without raised lateral veins; petals > 1 cm long
    3 Leaves pinnately or palmately compound (1-foliolate leaves sometimes also present).
          6 Leaves 1-pinnate, either odd-pinnate and (3-) 5-19-foliolate or even-pinnate and (4-) 6-8 (-14)-foliolate.
             7 Leaves opposite; stems and leaves unarmed.
               8 Axillary buds concealed beneath the base of the petioles on mature, leafy stems; leaflets (7-) 9-13; bark on older stems corky; [subfamily Zanthoxyloideae]
               8 Axillary buds exposed above the base of the leaf petioles on mature, leafy stems; leaflets 3-9 (-11); bark on older stems smooth to somewhat rough but never corky.
                 9 Fruit a drupe; diameter of mid-point of internodes of leafy branches usually 1-3 mm; internode lenticels usually < 0.3 mm long, mostly round (or absent); [native in FL and TX, and also planted and escaped in FL]; [subfamily Amyridoideae]
                 9 Fruit of 1-5 follicles; diameter of mid-point of internodes of leafy branches usually 3-6 mm; internode lenticels usually > 0.4 mm long and round to elongate; [planted and escaped in more northern parts of our area]; [subfamily Zanthoxyloideae]
             7 Leaves alternate; stems and leaves either unarmed, or armed with prickles.
                   10 Leaflets alternate on the rachis; fruit a berry, orange to red when ripe; stems and leaves unarmed; [subfamily Aurantioideae]
                   10 Leaflets opposite on the rachis; stems either not armed (Glycosmis) or stems (and also often leaves) armed with prickles (Zanthoxylum, except Z. flavum).
                     11 Fruit of 1-5 follicles; [subfamily Zanthoxyloideae]
          6 Leaves palmately 3-foliolate.
                       12 Branches armed with axillary spines; fruit a hesperidium; [subfamily Aurantioideae].
                          13 Petiole winged; stamens 20+; hesperidia 4-5 cm in diameter, dark yellow to orange when ripe, densely pubescent, usually with > 20 seeds (looking like a small, hairy orange)
                          13 Petiole not winged; stamens 6-10; hesperidia 1-1.5 cm in diameter, glabrous, red when ripe, with 1-4 seeds; spines usually paired at nodes; petals often 3
                            14 Fruit a drupe or few-seeded berry; [subfamily Amyridoideae]

Key F1: Key to Plantae

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1 Leaves 1- or 2-foliolate, if 1-foliolate then deeply notched and appearing bilobed (Bauhinia, which is also keyed in Key G).
  2 Leaves 1-foliolate (bilobed)
  2 Leaves 2-foliolate
    3 Leaflets elliptic to lanceolate, acute at the apex; petals white, not clawed; fruit a pinkish-red berry, mucilagenous or dry at maturity; plants shrubs
    3 Leaves cordate and deeply cleft (appearing 2-foliolate) or if subtly 2-foliolate, the lobes rounded at the ends; petals pink, clawed; fruit an elongated legume; plants shrubs or sometimes vines
1 Leaves 3-, 5-, to many-foliolate.
      4 Plant a liana, climbing by twining, by tendrils, or by adventitious roots.
        5 Leaves untoothed and unlobed; fruit a legume
        5 Leaves coarsely toothed or lobed; fruit a berry (except legume in Pueraria)
          6 Leaflets obovate or broadly elliptic (broadest at or above the middle), the teeth or lobes soley or primarily in the apical half of the leaf; plant climbing by tendrils; fruit a blue to black berry.
             7 Plants with leaves trifoliolate only, the blades fleshy, > 1 mm thick when fresh, the leaftlets ovate to oblong; inflorescence axillary (accompanying leaves, not opposing them); [tribe Cayratieae]
             7 Plants often with a mix of well-developed trifoliate leaves and (less-developed) tri-lobed, simple leaves (the lobes or leaflets broadly ovate to ovate-reniform), these herbaceous, the blades thin; inflorescence leaf-opposed; [tribe Cisseae]
          6 Leaflets orbicular or ovate (broadest at the middle or below the middle), the teeth or lobes primarily or solely in the basal half of the leaf; plant climbing by stem twining or by dense, reddish adventitious roots; fruit a legume (Pueraria) or whitish berry (Toxicodendron).
               8 Plant climbing by the stem twining; [plant not actually woody, but so robust as to often be assumed to be so]
               8 Plant climbing by dense, reddish adventitious roots attaching the stem to tree trunks or rock outcrops
      4 Plant a shrub or small tree (sometimes scrambling or occasionally high-climbing with the support of other vegetation, but lacking the specialized climbing structures listed above, e.g., Akebia).
                 9 Stems armed with small prickles or stout thorns.
                   10 Stems with stout thorns at the nodes; fruit a hesperidium (orange-like, but densely hairy)
                   10 Stems with many small prickles along the internodes (directly below the nodes; sometimes inconspicuous on the vegetative stems of Erythrina); fruit various: either a legume, berry, an aggregate of drupelets, or a hip.
                     11 Leaflets with 2 rounded lateral lobes near the base, otherwise entire; fruit a legume; corolla red
                     11 Leaflet bases cuneate to rounded, unlobed (sometimes cleft), but lacking 2 rounded, lateral lobes at their bases; fruit either a drupe (Eleutherococcus), berry (Triphasia), OR a hip or aggregate of drupelets (ROSACEAE); corolla variously colored.
                       12 Flowers 3-merous (sometimes with 4 or rarely with 5 petals); fruit a glabrous berry, reddish when ripened; [uncommon non-native, s. FL]
                       12 Flowers 4- or 5-merous (with 4 or 5 petals); fruit a drupe, an aggregate of drupes, or a hip; [collectively widespread natives and non-natives, including s. FL].
                          13 Inflorescence a compound umbel, notably rounded in shape; leaves 3-5-foliolate (often trifoliolate, sometimes palmately compound); fruit a drupe; [uncommon non-native, n. FL]
                          13 Inflorescence a panicle, not notably rounded in shape; leaves 3 or more foliolate; fruit an aggregate of drupelets or a hip; [natives and non-natives; widespread]
                            14 Leaflets serrulate, crenulate, serrate, with a few coarse and jagged teeth (spine-tipped or not), or shallowly lobed (Erythrina).
                                16 Leaflets 3-11 (usually 5+ per leaf, also keyed in F5); fruit a fleshy berry, red to dark orange at maturity; [uncommon non-native, s. FL]
                                16 Leaflets usually 3 (leaves typically trifoliolate); fruit a conspicuously winged samara (dry at maturity), greenish-brown at maturity; [natives, c. FL northward and westward]
                              15 Leaflets serrate, with a few coarse and jagged teeth (spine-tipped or not), or shallowly lobed (Erythrina).
                                  17 Leaflets with 2 prominent, rounded lobes near the base; fruit a legume; flowers > 3 cm long, corollas bilaterally symmetrical, red, in a terminal raceme
                                  17 Leaflets serrate and sometimes also cleft, or with a few coarse and jagged teeth (spine-tipped or not); fruit either a tan or red drupe or a red berry; flowers < 1 cm across, corollas radially symmetrical, green, yellow, or white, in axillary or terminal panicles or racemes
                                    18 Leaflets not spine-tipped; fruit a red or tan drupe; [collectively widespread]
                                         20 Leaflets 2-5 cm long (Hypelate) or 5-15 cm long (Ptelea); stems and branches tan to brown
                                           21 Leaflets obovate to oblanceolate, the apices usually rounded; leaves 2-5 cm long, often congested at branch tips; fruit a fleshy drupe, maroon or black-colored when ripened; flowers arranged in panicles; [s. FL only in our area]
                                           21 Leaflets usually ovate, the apices acute or acuminate; leaves 5-15 cm long, usually spaced throughout the stems, rarely congested at leaf tips; fruit a samara, brown when ripened; flowers arranged in cymes; [c. FL northward, widespread]
                                             22 Fruit a berry, a berry-like drupe, or a legume (not valvate but often dehiscent); leaves lacking a strong scent of horseradish.
                                               23 Petals white, small (ca. 4 mm long); fruit a pinkish-red berry, mucilagenous or dry at maturity
                                               23 Petals small to large, variously colored (including white); fruit a legume or if berry like, then white at maturity, often somewhat laterally flattened, and plants vining, rhizomatous shrubs (Toxicodendron).
                                                 24 Leaves pinnately trifoliolate, a rachis present as an extension of the petiole past the point of attachment of the 2 lateral leaflets, the terminal leaflet borne on a petiolule at the terminus of the rachis, with an obvious joint present between the rachis and petiolule; fruit a legume
                                                 24 Leaves palmately trifoliolate, the terminal leaflet typically with a longer petiolule than the lateral leaflets, but lacking a rachis (the petiolule of the terminal leaflet attached at the same point as the 2 lateral leaflets and unjointed); fruit a white, berry-like drupe (globose or often laterally somewhat flattened).