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Key to Rubiaceae

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1 Trees, shrubs, or woody vines.
  2 Prostrate or climbing woody vines (lianas), or sprawling shrubs.
    3 Leaf bases cordate, rounded, or truncate; leaves usually cordate, ovate, or deltoid shaped (occasionally hastate or broadly elliptic); corolla pale lilac colored; [non-native, se. US including FL; tribe Paederieae]
    3 Leaf bases cuneate to rounded but not cordate; leaves oblanceolate, lanceolate or linear; corolla white or yellow; [native, FL].
      4 Flowers and fruit sessile or subsessile; fruit yellow
      4 Flowers and fruit borne on pedicels or peduncles; fruit white
  2 Shrub or tree, plants upright.
        5 Inflorescence spherical or globular, in a tight round head; [collectively widespread].
          6 Inside of corolla pubescent; [natives and non-native; widespread, including s. FL]
             7 Fruits dry, dehiscent, composed of nutlets; lobes of the corolla smaller; [subfamily Cinchonoideae; tribe Naucleeae]
             7 Fruits fleshy, indehiscent, composed of drupe-like syncarps; lobes of the corolla larger (inflorescence with 1 petaloid calycophyll in M. citrifolia); [subfamily Rubioideae; tribe Morindeae]
        5 Inflorescence cymose, thyrsoid, or corymbose (the inflorescence more open, not globular); [Coastal Plain, from s. SC southward].
               8 Plants with paired spines.
                 9 Corolla lobes 4; leaves to ca. 1 cm long; fruit ca. 5 mm long
                 9 Corolla lobes 5; leaves ca. 2-5 cm long ; fruit ca. 10 mm long
               8 Plants unarmed, not bearing spines or thorns.
                   10 Flowers orange-red; leaves usually whorled; [subfamily Cinchonoideae; tribe Hamelieae]
                   10 Flowers white, green, or maroon; leaves predominantly opposite.
image of plant
Show caption*© Scott Ward
                     11 Leaves linear, revolute, and strongly congested at branch tips; [FL keys southward]
                     11 Leaves broad, not linear, nor strongly congested (except sometimes in Guettarda); [widespread, including s. FL].
                       12 Flowers solitary, terminal, appearing Rose or Magnolia-like; [horticultural waif; subfamily Ixoroideae; tribe Gardenieae]
image of plant
Show caption*© Alan M. Cressler
image of plant
Show caption*© Alan M. Cressler
                       12 Flowers in cymose or thyrsoid inflorescences, not appearing Magnolia or Rose-like (sometimes singular in Exostema, but the corolla is conspicuously salverform); [natives, s. SC southward through FL]
                          13 Corolla salverform, the tube long and slender, ca. (1.5-) 2-9 cm long, the petals noticeably shorter than the tube (or if of similar length then the lobes linear, as in Exostema); [c. and s. FL only in our area].
                            14 Leaves ovate, elliptic, or lanceolate, not conspicuously rounded in shape (or at least this not predominant); corolla tube 2-5 cm long, the corolla lobes often recurved apically, linear and of similar length to corolla tube; stamens conspicuously exerted; [s. FL]
                            14 Leaves sub-orbicular to oval, conspicuously rounded in shape (the surfaces scabrous in G. scabra); corolla tube (1.5-) 2-9 cm long, the corolla lobes shorter than the corolla tube; [c. and s. FL]
                          13 Corolla not salverform (or if the tube somewhat lengthened not 2-5 cm long), the corolla lobes broadened and not typically recurved apically; stamens exerted or not; [s. SC southward through FL].
image of plant
Show caption*© Scott Ward
image of plant
Show caption*© Alan M. Cressler
                              15 Inflorescence cymose; some calyx lobes expanded into pink or reddish “flags”, the corolla lobes often pink-dotted; leaves deciduous; domatia not present; [of s. SC southward]; [subfamily Ixoroideae; tribe Condamineeae]
image of plant
Show caption*© Alan M. Cressler
                              15 Inflorescences thyrsoid; calyx lobes inconspicuous; leaves evergreen; domatia present or absent in secondary abaxial vein axils; [of ne. FL southward].
                                16 Fruit large, fig-like (5-7 cm long berries), obovoid, green-colored when ripened and somewhat dull; [subfamily Ixoroideae; tribe Gardenieae]
                                16 Fruit smaller (pea-sized or smaller, ca. 4-6 mm in diameter), rounded and berry or drupe-like, white, red, or black colored when ripened, usually at least somewhat lustrous.
                                  17 Leaves with 8-14 pairs of prominently depressed secondary veins on the upper (adaxial) surface, the veins nearly arising perpindicular from the midvein and often curving (arcuate) toward the leaf margins (thus causing the leaf tissue to almost "rise" from between the veins), the blades herbaceous or membranous; fruit red; [subfamily Rubioideae; tribe Psychotrieae]
                                  17 Leaves usually with < 8 secondary veins, these not conspicuously depressed within the leaf blade (sometimes the midvein moderately depressed); the blades leathery; fruit black or white; [subfamily Cinchonoideae; tribe Chiococceae]
image of plant
Show caption*© Sequoia Janirella Wrens, some rights reserved (CC BY-NC), uploaded by Sequoia Janirella Wrens
image of plant
Show caption*© Keith Bradley
                                    18 Inflorescence elongate-thyrsoid, pedicels bent to one side, petals yellowish; ripened fruit white; plants often vine-like or sprawling shrubs
image of plant
Show caption*© Alan M. Cressler
                                    18 Inflorescence cymose or corymbose, usually terminal, petals whitish; ripened fruit black; plants upright shrubs
1 Herbs (or creeping subshrubs in Mitchella); [ADD Borreria]
                                         20 Fruit variously colored but not bright blue to purple, the calyx not partially persistent or inconspicuously so; [widespread natives and non-natives].
                                           21 Flowers paired, the ovaries connate and developing into a single fleshy red fruit; leaves roundish; creeping subshrub; [subfamily Rubioideae; tribe Mitchelleae]
                                           21 Flowers single or in inflorescences with multiple flowers, the fruits either dry or fleshy and yellowish or black; leaves various; herb; [subfamily Rubioideae; tribe Spermacoceae].
                                                 24 Flowers variously colored, often pinkish-purple or whitish-pink; leaf blades often > 5 cm long; plants perennial, erect, not succulent; [waif, c. and s. FL]
                                                 24 Flowers white; leaf blades < 5 cm long; plants annual, creeping or only partially erect, partially succulent; [uncommon exotic, SC s. to FL, w. to TX and AR]