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Key to Lithospermum

Boraginaceae

Lithospermum

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1 Corolla lobes acute to acuminate, erect (continuing the plane of the corolla tube); style exserted.
  2 Corolla lobes yellow to orange; nutlet 2.0-2.8 mm long; corolla lobes either 2.5-4× as long as wide and acuminate (L. virginianum) or 1.5-2× as long as wide, acute (O. decipiens).
    3 Stem hairs 2.5-5.0 mm long; corolla lobes 1.5-2× as long as wide, acute; tips of the anthers reaching the base of the corolla sinuses; [endemic to Ketona dolomite glades, Bibb County, c. AL]
    3 Stem hairs < 2.0 mm long; corolla lobes 2.5-4× as long as wide and acuminate; tips of the anthers below the corolla sinuses; [widespread in our area]
  2 Corolla lobes dull greenish-white; nutlet 2.5-3.0 mm long; corolla lobes 1.5-2× as long as wide, acute.
      4 Leaf vestiture solely of dense appressed hairs on both surfaces (the plant appearing ashy-white)
      4 Leaf vestiture at least in part of spreading or ascending hairs.
        5 Stems glabrescent (with widely scattered appressed hairs) below the inflorescence branches
        5 Stems persistently and obviously pubescent below the inflorescence branches.
          6 Upper leaf surface with hairs of similar length, these appressed to ascending; corolla 11-20 mm long; nutlets tapered to the base, lacking a collar; longest stem hairs near midstem < 2.2 mm long
          6 Upper leaf surface with hairs of two lengths, these spreading; corolla either 6-10 mm or 11-20 mm long; nutlets either flared at the base (forming a collar) or rounded to the base (lacking a collar); longest stem hairs near midstem either 2-4 mm long or < 2.2 mm long.
             7 Corolla 11-20 mm long; nutlets rounded and not at all constricted at the base; stem pubescence 2-4 mm long
             7 Corolla 6-10 mm; nutlets flared at the base, forming a collar; longest stem hairs near midstem < 2.2 mm long
1 Corolla lobes rounded, spreading; style included.
               8 Corolla white or yellowish-white, the tube 4-8 mm long.
                 9 Plant with basal rosette; lower cauline leaves about equal in size to the upper cauline leaves; leaves acute to obtuse
                 9 Plant lacking basal rosette; lower cauline leaves smaller than the upper cauline leaves; leaves acuminate or acute.
                   10 Upper stem internodes mostly 3-6 cm long; leaves mostly > 2 cm wide, acuminate
                   10 Upper stem internodes mostly 1-2 cm long; leaves mostly < 2 cm wide, acute
               8 Corolla yellow-orange, the tube 7-30 mm long.
                     11 Corolla tube 13-30 mm long; corolla lobes denticulate to lacerate; nutlets pitted
                     11 Corolla tube 7-14 mm long; corolla lobes entire; nutlets smooth.
                       12 Plant with dense, soft, appressed pubescence, the hairs usually without pustular bases; calyx lobes 6-8 mm long at maturity; nutlets 2-3 mm long; [mostly of rocky or clayey circumneutral soils of inland physiographic provinces]
                       12 Plant with scattered, stiff, spreading pubescence, the hairs with or without pustular bases; calyx lobes 10-15 mm long at maturity; nutlets 3.5-4.5 mm long; [variously of sandy acidic soils of the Coastal Plain or inland].
                          13 Pubescence with slender bases; mature calyx lobes flat; plants with 15-25 well-developed leaves below the inflorescence; [of sandy Coastal Plain habitats from se. VA southward]
                          13 Pubescence with pustular bases; mature calyx lobes strongly keeled; plants with (30-) 35-45 well-developed leaves below the inflorescence; [inland, known from inland provinces, PA, OH, IN, KY, IN, IL, MO, AR, and OK]