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Keyed in multiple places:

Click the number at the start of a key lead to highlight both that lead and its corresponding lead. Click again to show only the two highlighted leads. Click a third time to return to the full key with the selected leads still highlighted.

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 Fruits dry, dehiscent; [subfamily Cinchonoideae; tribe Naucleeae]
          6 Fruits fleshy, indehiscent; [subfamily Rubioideae; tribe Morindeae]
        5 Inflorescence cymose, thyrsoid, or corymbose (the inflorescence more open, not round and compact); [Coastal Plain, from s. SC southward].
             7 Plants with paired spines.
               8 Corolla lobes 4; leaves to ca. 1 cm long; fruit ca. 5 mm long
               8 Corolla lobes 5; leaves ca. 2-5 cm long ; fruit ca. 10 mm long
             7 Plants unarmed, not bearing spines or thorns.
                 9 Flowers orange-red; leaves usually whorled; [subfamily Cinchonoideae; tribe Hamelieae]
                 9 Flowers white, green, or maroon; leaves opposite.
image of plant
Show caption*© Scott Ward
                   10 Leaves linear, revolute, and strongly congested; [FL keys southward]
                   10 Leaves broad, not linear, nor strongly congested; [collectively more widespread]
                     11 Flowers solitary, terminal; [subfamily Ixoroideae; tribe Gardenieae]
image of plant
Show caption*© Alan M. Cressler
image of plant
Show caption*© Alan M. Cressler
                     11 Flowers in cymose or thyrsoid inflorescences.
image of plant
Show caption*© Scott Ward
image of plant
Show caption*© Alan M. Cressler
                       12 Inflorescence cymose; some calyx lobes expanded into pink or reddish “flags”; leaves deciduous; domatia not present; [of s. SC southward]; [subfamily Ixoroideae; tribe Condamineeae]
image of plant
Show caption*© Alan M. Cressler
                       12 Inflorescences thyrsoid; calyx lobes inconspicuous; leaves evergreen; domatia present in secondary vein axils; [of ne. FL southward]
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
                          13 Lateral veins 3-6 on either side of the midvein; fruit white; petals yellowish, > 6 mm long; [subfamily Cinchonoideae; tribe Chiococceae]
image of plant
Show caption*© Alan M. Cressler
                          13 Lateral veins 8-14 on either side of the midvein; fruit red; petals white, <5 mm long; [subfamily Rubioideae; tribe Psychotrieae]
1 Herbs (or creeping subshrubs in Mitchella).
                            14 Leaves whorled; [subfamily Rubioideae; tribe Rubieae]
                            14 Leaves opposite
                              15 Flowers paired, the ovaries connate and developing into a single fleshy red fruit; leaves roundish; creeping subshrub; [subfamily Rubioideae; tribe Mitchelleae]
                              15 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].
                                16 Carpels with few to many seeds.
                                  17 Corolla 5-lobed
                                  17 Corolla 4-lobed.
                                    18 Capsule longer than the calyx tube; flowers blue, pink, or white
                                    18 Capsule not longer than the calyx tube; flowers white
                                16 Carpels 1-seeded.
                                       19 Flowers in dense, terminal, involucrate heads; flowers 4- or-6-lobed; styles 3
                                       19 Flowers in axillary or terminal clusters, or single in axils, not involucrate; flowers 4-lobed; styles 2.
                                         20 Flowers usually solitary in leaf axils; fruit separating into 2 parts.
                                           21 Sepals 4 and similar in size; style entire; [of dry habitats]
                                           21 Sepals 2 (or 4, and then markedly dimorphic); style cleft; [of moist to wet habitats]
                                         20 Flowers in terminal and axillary clusters; fruits not separating into 2 parts.
                                             22 Carpels opening transversely
                                             22 Carpels opening longitudinally

Key J5: trees with opposite simple leaves with entire margins

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1 Leaves deciduous (medium to pale green, thin in texture); leaves strictly opposite.
  2 Leaves 10-70 cm wide, cordate or subcordate at the base; flowers 5-merous, bilaterally symmetrical, large (20-70 mm long), the petals connate into a tube; fruit a capsule.
    3 Flowers white to yellow; capsules linear, >10× as long as wide; leaf undersurface with curly simple hairs; nectar glands present in the main vein axils on the undersurface of the leaf (visible from the underside or the upperside in fresh leaves and herbarium specimens as a triangle 1-4 mm on a side)
    3 Flowers lavender; capsules ellipsoid, < 2× as long as wide; leaf undersurface with branched (dendritic or stellate) hairs; nectar glands absent
  2 Leaves 1-12 cm wide, cuneate to rounded at the base; flowers 4-6-merous, radially symmetrical, small to medium (< 25 mm long), the petals either connate into a tube or separate and clawed; fruit a drupe or capsule.
      4 Leaves with prominently parallel-arcing secondary veins; corolla 4-merous, < 8 mm long, white to cream; inflorescence a many-flowered corymb or head; flowers white to cream; fruit a drupe
      4 Leaves with complexly branching secondary and tertiary veins; corolla 5-6-merous, 12-25 mm long, either greenish-yellow and mottled with purple, or white, pink, or purple; inflorescence a few-flowered cyme or many-flowered cymose panicle; fruit a capsule.
        5 Leaves 4-20 cm long, 2.5-12 cm wide; petals connate into a 15-25 mm long tube, either greenish-yellow and mottled with purple; some calyx lobes expanding to 7 cm long and 5 cm wide, petaloid (pink to yellowish); capsule 2-valved; [native, in saturated, boggy seepages and streamheads, se. SC to FL]
        5 Leaves 2.5-7 cm long, 1.5-4 cm wide; petals separate, clawed, 12-20 mm long (including the 6-9 mm long claw), white, pink, or purple; calyx remaining small and sepaloid (3.5-5 mm long); capsule 4-6-valved; [introduced, persistent from planting in upland to moist situations]
1 Leaves evergreen (dark green or gray-green, thick in texture); leaves opposite or subopposite (offset by < 2mm from the opposing leaf).
          6 Mangroves, with one of various adaptations to growing in tidal or near-tidal, saline situations: prominent salt-excreting glands on the petiole (Laguncularia in COMBRETACEAE), or prop roots (Rhizophora in RHIZOPHORACEAE), or abundant pneumatophores (Avicennia in ACANTHACEAE); [FL and less commonly subtropical shores of other, especially Gulf Coast, southeastern states].
             7 Leaves broadly elliptic, light green on both surfaces, rounded to broadly cuneate at the base, rounded and often retuse at the tip; petiole with 2 prominent salt-excreting glands; plants with neither prop-roots from the trunk and branches, nor pneumatophores from the roots
             7 Leaves narrowly elliptic, dark green above, cuneate at the base, acute to obtuse at the tip; petiole without salt glands; plants with either prop-roots from the trunk and branches, or pneumatophores from the roots.
               8 Plants with numerous pneumatophores ascending from the roots and terminating in a blunt tip; leaves gray on the undersurface
               8 Plants with prominent prop-roots descending to the ground from the trunk and branches; leaves light green on the undersurface
          6 Non-mangroves; [collectively widespread].
                 9 Secondary leaf veins relatively few, further branching and reticulating into the tertiary vein structure; [collectively widespread].
                   10 Leaves strictly opposite, blue- or gray-green on both surfaces, suborbicular (about as wide as long), strongly aromatic when fresh
                   10 Leaves opposite or subopposite (offset by < 2mm from the opposing leaf); dark green above, pale green below; oblancolate, elliptic, or ovate (distinctly longer than wide), not aromatic when fresh
                     11 Twigs with spines; leaf venation with 3 primary veins from near the blade base; fruit a spherical berry, 5-12 cm long
                     11 Twigs lacking spines; leaf venation pinnate; fruit an elliptical drupe, < 2.5 cm long
                 9 Secondary leaf veins very many, closely parallel to one another and extending unbranched to the leaf margin.
                       12 Leaves elliptic, widest near the midpoint of the blade, ca. 2× as long as wide; flowers in axillary thyrses; fruit a 1-seeded drupe, 2-4 cm long
                       12 Leaves spatulate, widest towards the broadly rounded tip, ca. 1.2-1.6× as long as wide; flowers terminal on the branches, 1-3; fruit a leathery capsule, (4-) 6-9 (-12)-valved, 5-8 cm long