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Key to Trillium, Key C: trilliums with unmottled leaves and pedicellate flowers, of subgenus Delostylis and subgenus Callipetalon

Trilliaceae

Trillium

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1
Petals white with triangular red blaze (rarely entirely white or pinkish); anther sacs lavender to white, dehiscence extrorse; fruit a red berry; leaves long-acuminate; [of acidic sites in the Mountains, generally strongly associated with either Pinus, Tsuga, Picea, Rhododendron, or other heaths]; [genus Trillidium]
 ⇒ Trillidium undulatum
1
Petals white to deep pink, lacking a red blaze; anther sacs yellow, dehiscence introrse; fruit a white to greenish-white, fleshy, irregularly dehiscent capsule; leaves obtuse to acute (or somewhat acuminate in T. grandiflorum); [of less distinctly acidic sites, collectively widespread in our area].
  2
Pedicel declined below the leaves (rarely erect); sepals arcuate-recurved; anthers irregularly twisted outward; pollen egg-yolk yellow; [subgenus Delostylis]
 ⇒ Trillium catesbyi
  2
Pedicel inclined above leaves to strictly erect; sepals not arcuate-recurved; anthers erect, regular; pollen light yellow (richer yellow in T. grandiflorum).
    3
Sepals narrower than the petals, acute; anthers white to greenish-white between the anther sacs; leaves obtuse, acute, or acuminate; pedicel somewhat angled from the vertical.
      4
Ovary obscurely 3-lobed; leaves < 5 cm long, blue-green, obtuse; [subgenus Callipetalon]
 ⇒ Trillium nivale
      4
Ovary sharply 6-angled (-winged); leaves > 5 cm long, green, acute to acuminate.
        5
Petals obovate, tightly rolled at base, abruptly flared near the apex; leaves broadly elliptic, acuminate; style minute, < 1.0 mm long; [subgenus Callipetalon]
 ⇒ Trillium grandiflorum
        5
Petals elliptic, loose, gradually separating; leaves ovate, acute; style conspicuous, > 1.5 mm long; [subgenus Delostylis]
 ⇒ Trillium persistens
    3
Sepals about as broad as the petals or broader, obtuse; leaves obtuse; anthers purplish-green between anther sacs; pedicel erect through fruiting; [Trillium pusillum complex of subgenus Delostylis].
      6
Leaves with stomates on the upper surface, appearing farinose; [of n. GA]
        7
Leaves linear, > 4× as long as wide; [of n. GA]
 ⇒ Trillium georgianum
        7
Leaves ovate or elliptic, not linear, < 4× as long as wide; [of sw. AR, nw. LA and e. TX]
 ⇒ Trillium texanum
      6
Leaves without stomates on the upper surface, appearing glabrous.
        8
Pedicels < 10 (-12) mm long.
          9
Pedicels (0-) 0.5-1.0 mm long; leaves (1.5-) 2.0-2.4 (-2.9)× as long as broad; leaves (14-) 15-20 (-22.5) mm wide; filaments (4.5-) 4.6-5.8 (-8) mm long; [of upland forests of Mountains of w. VA and e. WV]
 ⇒ Trillium pusillum var. monticulum
          9
Pedicels (0.5-) 1.0-6.6 (-11) mm long; leaves (2.1-) 2.5-3.8 (-6)× as long as broad; leaves (6-) 10-17 (-25) mm wide; filaments (2.5-) 3-5 (-6.5) mm long; [of wetland forests].
             10
Anthers (3.2-) 4.5-6 (-7) mm long; stamens (5.7-) 8.4-10.9 (-12.5) mm long; stigmas (1-) 2.1-3 (-5) mm long; leaves elliptic; [of the outer Coastal Plain of e. MD, e. VA, and ne. NC]
 ⇒ Trillium pusillum var. 5
             10
Anthers (2.5-) 2.7-4.8 (-6.8) mm long; stamens (5.7-) 6-9.2 (-13.2) mm long; stigmas (1-) 1.2-2.5 (-4.7) mm long; leaves ovate; [of the upper Coastal Plain and Piedmont of ne. NC, se. VA, and Mountains of sw. VA].
               11
Pedicels (0.5-) 1-2.1 (-7) mm long; stamens (6-) 7.5-9.2 (-11) mm long; stigmas (1-) 2-2.5 (-4.7) mm long; [of upper Coastal Plain of e.VA]
 ⇒ Trillium pusillum var. virginianum
               11
Pedicels (1.2-) 1.8-6.6 (-11) mm long; stamens (5.7-) 6-7.6 (-13.2) mm long; stigmas (1-) 1.2-2 (-2.5) mm long; [of Piedmont to edge of upper Coastal Plain of ne. NC]
 ⇒ Trillium pusillum var. 4
          12
Leaves ascending; sepals ca. 1.4× as long as the petals; [of sphagnum bogs in the s. SC sandhills]
 ⇒ Trillium pusillum var. 3
          12
Leaves horizontal to declining; sepals 0.9-1.1× as long as the petals.
             13
Leaves narrower, (1.9-) 3-4.1 (-5.6)× as long as wide; pedicels (23-) 25-33 (-56) mm long; [of calcareous savannas and swamps]
 ⇒ Trillium pusillum var. pusillum
             13
Leaves broader, (2-) 2.7-3.4 (-5.5)× as long as wide; pedicels (7-) 13-30 (-45) mm long.
               14
Leaves ovate, acute; sepals (14-) 22-30 (-41) long, (4-) 6-11 (-17) mm wide, (2-) 3-4.3 (-5.6)× as long as wide; [generally of upland rocky slopes]
 ⇒ Trillium pusillum var. ozarkanum
               14
Leaves elliptic, rounded; sepals (13-) 18-25 (-30) long, (4-) 6-8 (-12) mm wide, (1.8-) 2.7-3.1 (-4)× as long as wide; [generally of swamps and floodplains]
 ⇒ Trillium pusillum var. 1