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Key to Trichogalium

Rubiaceae

Trichogalium

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1 Largest leaves < 8 mm long; flowers white, yellow, or creamy; plant an annual, 0.5-3 dm tall.
  2 Inflorescences terminal and axillary, with pedicels > 5 mm long; [of w. AR, OK, and TX]
  2 Inflorescences axillary, the flowers on pedicels < 2 mm long; [collectively widespread].
    3 Flowers (1-) 2-3 in small clusters in leaf axils, the pedicels 1-2 mm long; fruits and ovaries glabrous
    3 Flowers solitary, sessile or subsessile in the leaf axils, the pedicels 0.3-0.8 mm long; fruits and ovaries pubescent with hooked hairs.
      4 Flowers about as long as the subtending leaves; stems hispidulous
      4 Flowers shorter than the subtending leaves; stems glabrous
1 Largest leaves > 8 mm long; flowers white, creamy, greenish-purple, maroon, or purple; plant a perennial, 1-8 dm tall.
        5 Larger leaves 1-6 mm WIDE, mostly 4-20× as long as wide (or 2-3.5× as long as wide in G. bermudense); fruits smooth or pubescent (if pubescent, the hairs not hooked at the end, though they may curve through their length, except uncinate in G. texense), either fleshy or dry; flowers white or creamy; leaves normally of differing lengths and also often forming asymmetrical, 'sloppy' whorls (the angles between the leaves not being 90°).
          6 Fruits dry, and green, tan, or purplish; leaves herbaceous, deciduous, not glandular-punctate beneath.
          6 Fruits fleshy and blue-black; leaves firm, more-or-less evergreen, glandular-punctate beneath; [clade undetermined].
             7 Leaves elliptic, 7-18 mm long, 3-6 mm wide, 2-3.5× as long as wide
             7 Leaves linear, 15-25 mm long, 2-4 mm wide, 5-10× as long as wide
        5 Larger leaves 2.5-25 mm WIDE, mostly 1.5-5 (-8)× as long as wide; fruits uncinate-hispid (except smooth in G. latifolium and G. arkansanum); flowers greenish, purplish, purple-and-cream, or yellow (in G. cruciata); leaves normally of very similar length and forming a symmetrical, neat whorl; [clade VII].
               8 Corollas greenish, purplish, or purple-and-cream; flowers in terminal inflorescences; corolla tube longer.
                 9 Leaves widest below the middle, tapering to a long-acuminate apex, averaging about 3-5 (-8)× as long as wide; largest leaves 30-80 mm long, 2.5-20 mm wide.
                   10 Fruits smooth; flowers purple.
                     11 Leaves with 3-5 (-7) veins from the base, the lateral veins obvious; leaves 13-20 mm wide; [Appalachians]
                     11 Leaves with 1-3 veins from base, the lateral 2 veins obscure or absent; leaves 2.5-9 mm wide; [Interior Highlands]
                       12 Corollas densely silky-pubescent on the exterior surface; leaves 2.5-3.5 mm wide and 1-veined
                 9 Leaves widest at about the middle, tapering to an obtuse (or broadly acute) apex, averaging about 2-3× as long as wide; larger leaves 10-50 mm long, 5-25 mm wide.
                          13 Flowers (some of them) sessile or subsessile along the inflorescence branches; leaves 1.5-5 cm long, the larger usually > 2.5 cm long.
                            14 Veins on lower leaf surface glabrous or short-hispid with hairs < 0.3 mm long; lower leaf surface (between the veins) usually glabrous; larger leaves 1.5-2.5 (-4.0) cm long and 0.7-1.4 (-1.8) cm wide
                            14 Veins on lower leaf surface long-hirsute with longest hairs 0.3-0.7 mm long; lower leaf surface usually appressed pilose; larger leaves 2-5 cm long, 1-2.5 cm wide
                          13 Flowers all distinctly pedicelled; leaves 1-2.5 cm long
                              15 Stem pubescent with either straight or upwardly incurved hairs; plants erect; leaves 1.5-2.5× as long as wide
                                16 Stems pubescent on the angles with ± straight and spreading hairs (the upper part of the stem sometimes glabrous or nearly so); leaf blades usually pubescent with ± straight and spreading hairs, infrequently the hairs somewhat curved in the apical portion (i.e., the angle of curvature usually < 90 degrees)
                                16 Stems pubescent on the angles with incurved hairs (i.e., the angle of curvature mostly 120-180 degrees), straight and spreading hairs may be present in the proximal half of the stem (and then these transitioning to incurved hairs on the distal half of the stem); leaf blades usually pubescent with incurved hairs