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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 F5: Key to Plantae

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1 Leaves very large, > 10 dm long
1 Leaves small to large, < 10 dm long.
  2 Stems armed with prickles or stipular or nodal spines; leaves often also with prickles.
    3 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
    3 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.
      4 Leaves not aromatic when fresh, lacking pellucid punctate glands; leaves never with prickles on the rachis; leaflet apices rounded
image of plant
Show caption*© Mary Keim, some rights reserved (CC BY-NC-SA)
image of plant
Show caption*© Gary P. Fleming
      4 Leaves strongly aromatic when fresh, with conspicuous pellucid punctate glands; leaves often with prickles on the rachis; leaflet apices usually acuminate
  2 Stems unarmed (leaflets with spinose margins in some species, or the stem with dense hispid hairs, but these not particularly sharp to the touch).
          6 Plant an upright shrub or tree, not climbing.
             7 Plant a medium or tall tree.
               8 Leaves with stipules; flowers bilaterally symmetrical, papilionaceous, white, cream, or pink; stamens 10; fruit a legume; [collectively widespread in our area]
               8 Leaves without stipules; flowers radially symmetrical, whitish; stamens 5 or 10; fruit a single-seeded drupe; [FL peninsula]
             7 Plant a shrub or small tree to 7 (-10) m tall.
                 9 Leaf 2-5 cm long, with 5-7 leaflets
                 9 Leaf > 8 cm long, with 5-many leaflets.
                   10 Flowers bilaterally symmetrical, papilionaceous (reduced in Amorpha to a single petal); stamens 10; fruit a legume; leaves with stipules (stipulate).
                   10 Flowers radially symmetrical, stamens 4-5 (to 10+ in Simarouba); fruit either a drupe (Anacardiaceae, Simaroubaceae), or a 1-3-seeded berry or a samara (Picramniaceae); leaves without stipules (exstipulate).
                       12 Plants with pellucid (translucent) gland dots (usually variously present across vegetative and flowering parts)
                          13 Carpels remaining united, forming a compound fruit (the fruits various)
                          13 Carpels becoming distinct, each forming a simple drupe
        5 Leaflets serrate or crenate (sometimes minutely so, look closely).
                            14 Leaflets crenate or crenulate, the teeth rounded and coarse (Cupania) or often inconspicuous or minute.
                              15 Fruit a fleshy berry, red to dark orange at maturity; leaf surfaces often (but not always) with punctate glands; flowers white, solitary or in small fascicles; [uncommon non-native, s. FL]
                              15 Fruit a capsule, drupe, or shizocarp of mericarps, variously colored at maturity; leaf surfaces not glandular-punctate; flowers variously colored, the inflorescence paniculate or thyrsiform; [collectively widespread natives and non-natives, including s. FL].
                                16 Fruit a dehiscent capsule; mid to lower leaflets usually conspicuously alternate along the rachis, the leaflet crenations often coarse; [s. FL only in our area]
                                16 Fruit a drupe or schizocarp of 2-5 samaroid mericarps (these evidently winged); mid to lower leaflets usually opposite or subopposite along the rachis, the crenations often inconspicuous; [collectively widespread].
                                  17 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
                                  17 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
                                         20 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
                                         20 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
                                             22 Leaves lacking stipules; flowers cream or yellow; fruit either a drupe or an inflated membranaceous capsule.