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Key to Lamiaceae

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1 Fruit a fleshy drupe; plant a small tree, shrub, or sprawling vine; mature stems terete or obscurely 4-sided (by secondary growth).
  2 Flowers zygomorphic; palmately (3-) 5-7 (-9) foliolate or simple (V. rotundifolia); [subfamily Viticoideae]
  2 Flowers essentially actinomorphic; leaves simple.
    3 Stems pubescent with dendritic hairs; inflorescence axillary; calyx 0.5-2 mm, lobes diminutive to nearly obsolete
    3 Stems glabrous or pubescent with simple (unbranched) hairs; inflorescence terminal (rarely only axillary); calyx lobes conspicuous or diminuitive.
      4 Corolla 5-40 mm long; calyx 5-18 mm, the lobes conspicuous, the calyx length often surpassing the fruit when mature; [subfamily Ajugoideae]
      4 Corolla 2-5 mm long; the calyx lobes inconspicuous and not surpassing the mature fruit; [subfamily Premnoideae]
1 Fruit a schizocarp of 4 dry mericarps; plant either an herb or a shrub to 5 (-20) dm tall; mature stems usually distinctly 4-sided (sometimes terete or obscurely 4-sided).
        5 Calyx with either a distinctly enlarged protuberance on the upper surface, or the upper lobe expanded and “cap-like”.
          6 Calyx with 5 lobes, clearly separate apically, with the upper lobe expanded and “cap-like”
          6 Calyx with 2 entire lobes joined at the margins, rounded apically, with a distinct protuberance on the upper surface
        5 Calyx without an enlarged protuberance or “cap-like” upper lobe.
             7 Upper lip of corolla greatly reduced or lobes laterally disposed, thus the corolla appearing to consist of one large lower lip; [subfamily Ajugoideae].
               8 Lower lip with 2-4 lobes; flowers yellow or deep blue-purple; plants stoloniferous
               8 Lower lip appearing 5-lobed (proximal 2 lateral, erect lobes represent the cryptic upper lip); flowers white to pink; plants cespitose
             7 Upper lip of corolla conspicuous, flaring or galeate.
                 9 Plants distinctly repent and rooting at the nodes, or producing elongate stolons.
                   10 Plants repent.
                     11 Herbs; leaves cordate-reniform, coarsely crenate, the blade > 1 cm long; inflorescence of axillary cymules; corollas 10-20 mm
                     11 Subshrubs; leaves ovate to elliptic, entire, the blade < 1 cm long; inflorescence a terminal thyrse; corollas 4-5 mm
                   10 Plants stoloniferous.
                       12 Inflorescence in dense axillary verticils; calyx and corolla actinomorphic, calyx 4-5-lobed, flowers 3-4 mm long
                       12 Inflorescence terminal; calyx and corolla zygomorphic, calyx 5-lobed, flowers 20-30 mm long
                 9 Plants not distinctly repent or stoloniferous.
                          13 Calyx with 6-10 lobes or teeth.
                            14 Calyx zygomorphic, canescent with simple trichomes, spinose lobe tips straight
                            14 Calyx actinomorphic or essentially so, densely pubescent with stellate hairs, spinose lobe tips uncinate
                          13 Calyx with 5 or fewer lobes or teeth.
                              15 Calyx with 3-4 prominent lobes (rarely 5, if one includes small teeth).
                                16 Calyx and corolla essentially actinomorphic
                                16 Calyx and corolla zygomorphic.
                                  17 Calyx with 4 unequal primary lobes; flowers large, 2.5-3.5 cm long, in bracteate terminal racemes
                                  17 Calyx with 3 primary lobes (upper lobe occasionally with 3 apiculate teeth, e.g. Salvia lyrata); flowers 3 cm or less, in terminal thyrses.
                                    18 Stamens 4; calyx enveloped and partially concealed by subtending bracts
                                    18 Stamens 2; calyx not enveloped by subtending bracts.
                                       19 Shrubs; calyx with simple and dendritic hairs; leaves revolute, coriaceous
                                       19 Herbs; calyx with simple trichomes; leaves non-revolute, margins various, membranaceous
                              15 Calyx usually with 5 prominent lobes (except for Clinopodium with rarely fused upper lobes).
                                         20 Fertile stamens 0-2.
                                           21 Calyx actinomorphic or essentially so; corollas actinomorphic or zygomorphic.
                                             22 Corolla actinomorphic, lobes spreading and nearly equal (one lobe slightly emarginate and/or enlarged).
                                               23 Inflorescences axillary; foliage not or faintly aromatic
                                               23 Inflorescences terminal; foliage strongly aromatic
                                             22 Corolla zygomorphic (bilabiate).
                                                 24 Inflorescence in loose terminal and axillary cymules; corollas not galeate or arching
                                                 24 Inflorescence densely capitate (often also axillary); corollas strongly galeate, arching
                                           21 Calyx and corollas clearly zygomorphic.
                                                    25 Corolla 7-20 mm; inflorescence a densely clustered terminal or axillary cyme, or a well developed panicle.
                                                      26 Inflorescence a dense cluster of one or more terminal cymules (occasionally just axillary); lower lip of corolla not fringed
                                                      26 Inflorescence a panicle; lower lip of corolla conspicuously fringed
                                                    25 Corolla ca. 3-10 mm long; inflorescence a loose axillary cyme or slender terminal spike or spike-like panicle.
                                                        27 Corolla 3.5-4 mm, borne 2 per node in a slender terminal spike; middle lobe of upper calyx reduced
                                                        27 Corolla 4-10 mm, borne in axillary cymes or spike-like panicle; upper calyx lobes similar.
                                                          28 Flowers in loose axillary cymes; calyx gibbous, throat closed by hairs; corollas ca. 4-5 mm long
                                                          28 Flowers in a spike-like panicle; calyx not gibbous or closed by hairs; corollas ca. 10 mm long
                                         20 Fertile stamens 4.
                                                            29 Stamens ascending under the upper corolla lip, either included within the tube (or at least not clearly exserted beyond it).
                                                              30 Calyx actinomorphic.
                                                                 31 Flowers borne in terminal verticils or thyrses, with reduced bracteal leaves.
                                                                   32 Calyx 15-nerved; verticils tightly aggregated
                                                                   32 Calyx 5-10-nerved; verticils well spaced
                                                                 31 Flowers borne in axils of well-developed leaves, or a terminal raceme with 1 flower per node.
                                                                     33 Calyx lobes with thickened spinescent apices.
                                                                       34 Stems often with swollen nodes (areas just below appear dark and sunken upon drying, except G. ladanum); hairs of the stem either exclusively hispid or short recurved and mixed with longer glandular trichomes; corolla 15-28 mm long
                                                                       34 Stems without swollen nodes; hairs of the stem finely and softly retrorse, generally lacking glandular hairs (though sessile glands may be present); corolla 5-14 mm long.
                                                                         35 Corolla 5-7 mm long, not much longer than the calyx, weakly bilabiate and lacking an annulus
                                                                     33 Calyx lobes without spinescent apices (although lobes may be pointed or acute).
                                                                           36 Flowers in terminal racemes, corolla tube broadly inflated
                                                                           36 Flowers borne in axils of well developed leaves, corolla tube not broadly inflated.
                                                                              37 Verticils 2-6-flowered, loose; corollas 5-7 mm
                                                                              37 Verticils 6-12-flowered, compact; corollas 10-30 mm.
                                                                                38 Corolla 10-15 mm long; calyx with 10+ nerves
                                                                                38 Corolla 10-30 mm long; calyx 5-nerved
                                                              30 Calyx zygomorphic.
                                                                                  39 Shrubs, diffusely branched; [restricted to se. Coastal Plain and Cumberland Plateau]
                                                                                  39 Herbs, branched or unbranched; [collectively widespread].
                                                                                    40 Calyx teeth distinctly white or pink, noticeably different from the tube
                                                                                    40 Calyx teeth coloration not noticeably different from the tube.
                                                                                      41 Flowers 1 per bracteal axil.
                                                                                        42 Corolla nearly regular, 4-6 mm long.
                                                                                        42 Corolla bilabiate, >10 mm long
                                                                                      41 Flowers 2-many per bract or leaf axil.
                                                                                           43 Plants lemon-scented, flowers in the axils of well-developed leaves
                                                                                           43 Plants mint-scented or non-aromatic, flowers terminal and/or axillary.
                                                                                             44 Upper median calyx lobe longer and wider than the other 4; flowers terminal
                                                                                             44 Upper lobes differing in sinus depth and/or size from the lower lobes; flowers borne variously.
                                                                                               45 Bracts broadly rounded, apiculate or absent.
                                                                                                 46 Bracts broadly rounded, apiculate; inflorescence terminal
                                                                                                 46 Bracts wanting; inflorescence axillary
                                                                                               45 Bracts setaceous or elliptic, but not broadly rounded or apiculate, present.
                                                                                                   47 Calyx clearly bilabiate; corollas 7-15 mm long
                                                                                                   47 Calyx scarcely bilabiate; corollas 5-7 mm long
                                                            29 Stamens (at least some) well exserted beyond the upper corolla lobe.
                                                                                                     48 Lower lip of corolla distinctly fringed
                                                                                                     48 Lower lip of corolla not fringed.
                                                                                                        49 Calyx zygomorphic.
                                                                                                          50 Flowers in dense terminal capitate clusters, subtended by large bracteal leaves (these often whitened on the upper surface and especially towards the base)
                                                                                                          50 Flowers borne otherwise.
                                                                                                            51 Flowers borne in few-flowered cymose axillary clusters, overall appearing paniculate; [subfamily Ajugoideae]
                                                                                                            51 Flowers borne in a spike-like terminal thyrse.
                                                                                                              52 Corolla pink to lavender or white, 11-17 mm long
                                                                                                              52 Corolla blue (rarely white), 7-12 mm long
                                                                                                        49 Calyx actinomorphic.
                                                                                                                53 Flowers borne in a dense terminal spike, 2-3-verticilled globose head, or spiciform thryse.
                                                                                                                  54 Inflorescence secund
                                                                                                                  54 Inflorescence terete.
                                                                                                                     55 Small plants to ca. 30 cm; leaves short, sessile, linear- lanceolate with revolute, entire margins; [endemic to FL and se. GA]
                                                                                                                     55 Large plants, well over 30 cm tall; leaves often petiolate, broadly ovate or lanceolate, margins not revolute or entire; [collectively widespread].
                                                                                                                       56 Bracts broadly rounded; corolla distinctly bilabiate; plants 1-3 m tall
                                                                                                                       56 Bracts linear-lanceolate; corolla nearly regular; plants < 1 m tall
                                                                                                                53 Flowers borne in axillary verticils or terminal (capitate to loosely flowered) clusters.
                                                                                                                         57 Flowers in axillary clusters, corolla nearly regular.
                                                                                                                           58 Axillary clusters loose, 1-3-flowered; [subfamily Ajugoideae]
                                                                                                                           58 Axillary clusters dense, many-flowered; corolla white-pink
                                                                                                                             59 Stems scabrous; corolla mostly blue-violet
                                                                                                                             59 Stems glabrous to pubescent; corolla mostly white-pink
                                                                                                                         57 Flowers in densely capitate or loosely flowered terminal clusters, corolla distinctly bilabiate.
                                                                                                                               60 Flowers in loosely branched terminal and axillary cymes
                                                                                                                               60 Flowers densely capitate cluster or terminal spike of well spaced verticils.
                                                                                                                                  61 Inflorescence either capitate or a spike, not subtended by large bracteal leaves
                                                                                                                                  61 Inflorescence capitate, subtended by large bracteal leaves (these often whitened on the upper surface and especially towards the base)