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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 a berry; [subfamily Aurantioideae]
                     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
                       12 Branches unarmed; fruit a drupe, few-seeded berry, or samara.
                            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 untoothed and unlobed
        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
               8 Stems unarmed.
                     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]
                     11 Leaflets entire and unlobed.
                              15 Terminal leaflet sessile.
                                16 Leaflets < 2 cm long; stems and branches dark green
                                16 Leaflets 5-15 cm long; stems and branches tan to brown
                              15 Terminal leaflet with a petiolule.
                                  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).
                                    18 Leaves palmately or palmately-pedately compound.
                                       19 Leaves palmately-pedately 5-foliolate (the lateral 2 leaflets on each side borne on a common Y-shaped stalk).
                                         20 Leaflets entire; sap milky
                                         20 Leaflets toothed; sap clear
                                       19 Leaves palmately compound (all the leaflets attached at a single point).
                                           21 Leaves > 6 dm wide
                                           21 Leaves < 3 dm wide.
                                             22 Leaflets with entire margins
                                             22 Leaflets with serrate margins.
                                               23 Stems armed with prickles scattered in the internodes
                                               23 Stems unarmed or with paired nodal spines.
                                                 24 Inflorescence an umbel; leaves evergreen, glossy; stems often with paired nodal spines
                                                 24 Inflorescence a panicle; leaves deciduous, dull; stems unarmed
                                    18 Leaves pinnately, bipinnately, or complexly compound.
                                                    25 Leaves at least in part pinnate-pinnatifid, 2-pinnate, or otherwise more complexly compound than 1-pinnate.
                                                      26 Leaves evenly 2-pinnately compound
                                                      26 Leaves oddly pinnate-pinnatifid, 2-pinnately compound, or more complexly compound than 2-pinnate.
                                                        27 Leaves pinnate-pinnatifid, with 7-19 leaflets, each leaflet pinnatifid into narrowly lanceolate lobes; {upper leaflet surface dark green, lower surface silvery with gray sericeous pubescence}
                                                        27 Leaves 2-pinnately compound, or even more complexly compound.
                                                          28 Plant a liana, climbing by tendrils
                                                          28 Plant a shrub or tree, not climbing.
                                                            29 Plant armed with prickles on the stem, and sometimes also on the axes and main veins of the leaves
                                                            29 Plant unarmed.
                                                              30 Plant a shrub, < 2.5 m tall.
                                                                 31 Foliage green; leaflets ovate, acute at the tip; flowers 3-merous, the tepals white or cream; fruit a red berry
                                                                 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
                                                              30 Plant a tree, > 3 m tall when flowering and fruiting.
                                                                   32 Leaflets entire
                                                                   32 Leaflets serrate.
                                                                     33 Fruit a globose drupe, tan at maturity, 10-15 mm in diameter; inflorescence an axillary panicle; corolla lavender
                                                                     33 Fruit an inflated capsule, 30-50 mm long; inflorescence a terminal thyrse; corolla yellow
                                                    25 Leaves 1-pinnately compound.
                                                                       34 Leaves even-pinnately compound (generally with 2 leaflets at the apex of the rachis, these obviously and symmetrically paired).
                                                                         35 Leaflets rounded to obtuse at the apex (or acute to acuminate in Gymnocladus); fruit a legume; inflorescence various, but not as below
                                                                         35 Leaflets acuminate at the apex; fruit a drupe or capsule; inflorescence a panicle with many, small, radially symmetrical flowers.
                                                                           36 Fruit a capsule.
                                                                           36 Fruit a drupe.
                                                                              37 Tree dioecious; drupe ca. 5 mm long; stamens (of male flowers) 3-5 (-7)
                                                                              37 Tree bisexual; drupe ca. 13 mm long; stamens 8-10
                                                                       34 Leaves odd-pinnately compound (generally with a single leaflet at the terminus of the rachis).
                                                                                38 Leaves very large, > 10 dm long
                                                                                38 Leaves small to large, < 10 dm long.
                                                                                  39 Stems armed with prickles or stipular or nodal spines; leaves often also with prickles.
                                                                                    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.
                                                                                      41 Leaves not aromatic when fresh, lacking pellucid punctate glands; leaves never with prickles on the rachis; leaflet apices rounded
                                                                                      41 Leaves strongly aromatic when fresh, with conspicuous pellucid punctate glands; leaves often with prickles on the rachis; leaflet apices usually acuminate
                                                                                  39 Stems unarmed (leaflets with spinose margins in some species, or the stem with dense hispid hairs).
                                                                                        42 Leaflets entire.
                                                                                           43 Plant a liana, climbing by twining
                                                                                           43 Plant an upright shrub or tree, not climbing.
                                                                                             44 Plant a medium or tall tree.
                                                                                               45 Leaves with stipules; flowers bilaterally symmetrical, papilionaceous, white, cream, or pink; stamens 10; fruit a legume; [collectively widespread in our area]
                                                                                               45 Leaves without stipules; flowers radially symmetrical, whitish; stamens 5 or 10; fruit a single-seeded drupe; [FL peninsula]
                                                                                             44 Plant a shrub or small tree to 7 (-10) m tall.
                                                                                                 46 Leaf 2-5 cm long, with 5-7 leaflets
                                                                                                 46 Leaf > 8 cm long, with 5-many leaflets.
                                                                                                   47 Flowers bilaterally symmetrical, papilionaceous (reduced in Amorpha to a single petal); stamens 10; fruit a legume; leaves with stipules.
                                                                                                   47 Flowers radially symmetrical, stamens 4-5; fruit either a drupe (Anacardiaceae), or a 1-3-seeded berry or a samara (Picramniaceae); leaves without stipules.
                                                                                                     48 Inflorescence a panicle; fruit a drupe; [collectively widespread]
                                                                                                     48 Inflorescence a raceme or compound thyrse; fruit a samara or 1-3-seeded berry; [s. FL]
                                                                                        42 Leaflets serrate or crenate.
                                                                                                        49 Leaflets crenate, the teeth rounded and often inconspicuous.
                                                                                                          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
                                                                                                        49 Leaflets serrate.
                                                                                                            51 Leaf serrations spinose
                                                                                                            51 Leaf serrations not spinose.
                                                                                                              52 Inflorescences axillary.
                                                                                                                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
                                                                                                              52 Inflorescences terminal.
                                                                                                                  54 Inflorescence corymbose (flat-topped or rounded, as wide as long or wider); fruit a red pome
                                                                                                                  54 Inflorescence paniculate (longer than wide); fruit various (see below), but not as above.
                                                                                                                     55 Leaves stipulate; flowers bright white; fruit an aggregate of 5 follicles
                                                                                                                     55 Leaves lacking stipules; flowers cream or yellow; fruit either a drupe or an inflated membranaceous capsule.
                                                                                                                       56 Fruit a drupe
                                                                                                                       56 Fruit an inflated membranaceous capsule
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