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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 F: woody angiosperms with alternate, compound leaves

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1 Leaves 2-foliolate or 1-foliolate (and then deeply notched).
  2 Leaves 1-foliolate (2-lobed)
  2 Leaves 2-foliolate
1 Leaves 3-, 5-, to many-foliolate.
    3 Leaves 3-foliolate.
      4 Plant a liana, climbing by twining, by tendrils, or by adventitious roots.
        5 Leaves coarsely toothed or lobed. {add Eleutherococcus trifoliatus ARALIACEAE}
          6 Leaflets obovate or broadly elliptic (broadest at or above the middle), the teeth or lobes primarily or solely in the apical half of the leaf; plant climbing by leaf-opposed tendrils
          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.
             7 Plant climbing by the stem twining; [plant not actually woody, but so robust as to often be assumed to be so]
             7 Plant climbing by dense, reddish adventitious roots attaching the stem to tree trunks or rock outcrops
      4 Plant a shrub (sometimes scrambling or occasionally high-climbing with the support of other vegetation, but lacking the specialized climbing structures listed above).
               8 Stems armed with small prickles or stout thorns.
                 9 Stems with stout thorns at the nodes; fruit a hesperidium (orange-like, but densely hairy)
                 9 Stems with many small prickles along the internodes; fruit either a legume, or an aggregate of drupelets, or a hip.
                   10 Leaflets with 2 rounded lateral lobes near the base, otherwise entire; fruit a legume
                   10 Leaflets serrate and sometimes also cleft; fruit either an aggregate of drupelets or a hip
                     11 Leaflets serrulate, crenulate, serrate, with a few coarse and jagged teeth (spine-tipped or not), or shallowly lobed.
                       12 Leaflets serrate, with a few coarse and jagged teeth (spine-tipped or not), or shallowly lobed.
                          13 Leaflets with 2 prominent, rounded lobes near the base; fruit a legume; flowers > 3 cm long, corollas bilaterally symmetrical, red, in a terminal raceme
                          13 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
                            14 Leaflets with a few spine-tipped teeth; fruit a red berry; [TX westwards]
                            14 Leaflets not spine-tipped; fruit a red or tan drupe; [collectively widespread]
                                16 Leaflets < 2 cm long; stems and branches dark green
                                16 Leaflets 5-15 cm long; stems and branches tan to brown
                                  17 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
                                  17 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)
    3 Leaves with 5-many leaflets (poorly developed leaves in some species with only 3 leaflets).
                                       19 Leaves palmately-pedately 5-foliolate (the lateral 2 leaflets on each side borne on a common Y-shaped stalk).
                                                            29 Plant armed with prickles on the stem, and sometimes also on the axes and main veins of the leaves
                                                                 31 Foliage blue-green; leaflets obovate, rounded or notched at the tip; flowers 4-5-merous, the sepals green, the petals yellow; fruit a capsule
                                                                                    40 Leaves with conspicuous leafy stipules, often adnate to the petiole; plant a liana or small to medium shrub; leaves serrate, often sharply and prominently so; leaves not strongly aromatic when fresh, lacking pellucid punctate glands on the surface
                                                                                    40 Leaves lacking leafy stipules; plant a tree or tall shrub; leaves entire or obscurely crenate or serrate; plant a tree or tall shrub; leaves either strongly aromatic when fresh, with conspicuous pellucid punctate glands or not aromatic and not pellucid-punctate.
                                                                                                          50 Leaflets with obscure crenations, not as below nor bearing glands; leaf rachis narrowly to conspicuously winged, especially towards the tip; fruit a drupe; plant a shrub or small tree
                                                                                                          50 Leaflets (especially the basal and on the basalscopic side) with 1-5 large rounded teeth, each bearing a prominent dark green gland; leaf rachis not winged; fruit a schizocarp, with 2-5 samaroid mericarps; plant a medium to large tree
                                                                                                                53 Plant a tree, freely branched; rhizome inner bark not brightly colored; flowers unisexual, the male flowers in catkins, the female flowers solitary or few in a spike, the perianth greenish or tan and inconspicuous; fruit a nut covered by a dehiscent or indehiscent involucre
                                                                                                                53 Plant a short shrub, < 1 m tall, little branched; rhizome inner bark of fresh plants bright yellow; flowers bisexual, petals absent, the 5 petaloid sepals maroon; inflorescence a drooping panicle from the base of the new year’s growth; fruit an aggregate of follicles
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