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Key to Liatris

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1 Pappus plumose, the barbels along each pappus bristle mostly 0.5-1.0 mm long or longer.
  2 Inner phyllaries with apices prolonged, slightly dilated, and petaloid (white to yellow, pink, or purplish); heads 3-5 mm in diameter, with 4-6 flowers per head.
    3 Heads pedunculate; [east of the Mississippi River in e. LA, s. MS, AL, FL, GA, and SC].
      4 Phyllary apices white to cream or light yellow
    3 Heads sessile (plants that are top-injured or knocked over and prostrate may develop pedunculate heads); [west of the Mississippi River in AR, OK, LA, and TX].
        5 Phyllary apices loosely erect, few if any diverging > 30 degrees from the axis of the head; colored portions of the phyllaries lavender to pink or magenta (rarely mainly green with whitish margins); [widespread in w. and s. AR, e. and se. OK, w. LA, and e. TX]
        5 Phyllary apices spreading to recurving, many or most spreading at more than 30 degrees from the axis of the head; colored portions of the phyllaries either white to cream or light yellow or lavender to pink or magenta; [e., se., and s. TX].
          6 Corms depressed-globose, flat or rounded at the base; phyllary apices white to cream or light yellow (rarely lavender to pink or magenta); [e. TX, from c. Bastrop County and Travis County northeastwards]
          6 Corms elongate and tapering downwards (napiform or turnip-like); phyllary apices lavender to pink or magenta; [s. and se. TX, from s. Bastrop County, Fayette County, and Calhoun County southwestwards].
  2 Inner phyllaries not prominently petaloid; heads 10-20 mm in diameter, with 2-60 flowers per head.
             7 Heads in corymbiform or broadly racemiform arrays, at least some of the heads on peduncles 20-70 mm long.
               8 Involucres 8-11 mm in diameter; inflorescences corymbiform; leaves 2-5 mm wide; [e. TX]
               8 involucres 15-20 mm in diameter; inflorescences broadly racemiform (at least when well-developed, with > 5 heads); leaves 1-2 (-2.5) mm wide; [c. peninsular FL scrub]
             7 Heads in narrowly racemiform or spiciform arrays (or borne singly), the heads sessile or on short peduncles 1-10 (rarely to 25) mm long.
                 9 Leaves with 3-5 nerves; florets 10-60 per head; corolla lobes densely hairy.
                   10 Outer phyllaries as long as or (more usually longer than) the inner phyllaries, spreading or reflexed, the spreading portion typically > 2 mm long.
                     11 Heads usually single, each subtended by foliaceous bracts longer than the head; ; stems glabrous; [Ouachita Mountains of AR and e. OK]
                     11 Heads in racemiform arrays; stems glabrous or hairy; [collectively widespread].
                   10 Outer phyllaries shorter than the inner phyllaries, erect-appressed to spreading or reflexed, the spreading portion 0-2 mm long.
                          13 Stems and leaves usually glabrous; inner phyllaries usually apically rounded to truncate, apiculate, all essentially erect and appressed, usually with a narrow hyaline border
                          13 Stems and leaves hirsute to hirsute-pilose; inner phyllaries apically acute-acuminate, all usually spreading to reflexed on the distal 1/3 (outer) to 1/5 (inner), usually without a hyaline border
                 9 Leaves with 1 nerve (or sometimes with 3-5 nerves in L. acidota); florets either (2-) 3-6 (-8) or 8-14 (-16) per head.
                            14 Heads borne in loose spiciform arrays, the heads spaced widely and the stem therefore not obscured; florets 8-14 (-16) per head; [se. TX]
                            14 Heads borne in dense spiciform arrays, the heads overlapping and the stem therefore generally obscured; florets (2-) 3-6 (-8) per head.
                                16 Leaves with 3 (-5) nerves; basal leaves fibrous-persistent; cauline leaves abruptly reduced in size; [prairies, Coastal Plain of w. LA and e. TX].
                                16 Leaves with 1 nerve; basal leaves withering completely; cauline leaves nut reduced or only gradually so; [collectively more widespread from MO and KS south to w. LA and e. and c. TX].
                                    18 Phyllaries 6-11, in 2-3 series, oblong-lanceolate to lanceolate-triangular, subequal (the inner 11-12 mm long), the apices acute to acute-attenuate (sometimes with narrow tips), lateral veins usually evident beyond middle, continuing nearly to tips); flowering mid Jul-Aug (-Sep)
                                    18 Phyllaries 11-18 in (4-) 5-6 series, mostly oblong-obovate, unequal (the inner 7-9 mm long), apices obtuse to truncate-rounded (each tipped by thick, often indurate apicula or mucros), lateral veins usually not evident beyond middle or 2/3s point; flowering mostly mid-late Aug (-Oct)
1 Pappus barbellate, the barbels along each pappus bristle 0.1-0.3 (-0.4) mm long.
                                       19 Heads mostly 1-30 in subcorymbiform or corymbiform arrays; [of either c. peninsular FL or Bibb Co., AL]
                                       19 Heads usually > 10 in a spiciform or racemiform arrangement; [collectively widespread].
                                                 24 Basal and lower cauline leaves (2-) 4-8 mm wide, cauline usually abruptly reduced in size at ca. midstem, continuing distally as linear, bract-like leaves; heads in a densely (- to loosely) spiciform arrangement; involucres 7-9 mm, purplish to greenish; florets 5-6 (-8) per head; [mainly of the Coastal Plain]
                                                 24 Basal and lower cauline leaves 4-10 (-20) mm wide, cauline usually gradually reduced in size distally; heads in a densely to loosely spiciform arrangement; involucres (7-) 8-11 mm, usually greenish; florets (4-) 6-8 (-12) per head; [of the Mountains and Piedmont]
                                                                     33 Heads rigidly ascending, appressed to the rachis and to each other, densely overlapping; phyllary margins usually not ciliolate; phyllary tips erect; [FL peninsula, Panhandle, and sw. GA and s. AL]
                                                                     33 Heads spreading to ascending, not strongly overlapping; phyllary margins ciliolate; phyllary tips slightly spreading; [FL Panhandle (Franklin and Wakulla counties]
                                                                           36 Stems and basal leaves glabrous; basal leaves mostly arising from congested nodes at very base of plant, (1-) 2-6 (-9) mm wide, abruptly reduced in size distally, surfaces minutely white-dotted by stomates, not glandular-punctate
                                                                              37 Leaves in a diffuse, few-leaved basal rosette, 2-3 mm wide and 20-30 cm long, mostly somewhat ascending; culms (60-)75-100(-150) cm tall, 2-3 mm wide, the inflorescence averaging 25% of the culm height; flowering mostly from October to November, during the dry season in peninsular Florida
                                                                              37 Leaves in a well-defined, densely leafy basal rosette, (4-)5-7(-10) mm wide and 15-20 cm long, mostly lax and spreading, not ascending; culms (40-)50-80(-120) cm tall, 4-6 mm wide, the inflorescence averaging half the culm height; flowering mostly from July to September, during the wet season in peninsular Florida
                                                                           36 Stems and basal leaves glabrous to very sparsely pilose, leaves usually with a few spreading cilia near insertion; basal and lower cauline leaves arising from numerous, separated nodes on proximal part of stem, 1-2 (-2.5) mm wide and relatively even-sized, surfaces glandular-punctate
                                                                                  39 Heads densely arranged, on internodes 1-2 (-5) mm long, often secund; phyllary apex sharply acuminate-acute, distinctly involute, lamina relatively thin, glands consistently present and superficial at least on proximal portion; florets 4-7 (-9); basal and lower cauline leaves 2-5 mm wide, gradually reduced in length distally
                                                                                  39 Heads loosely arranged, on internodes 6-15 (-20) mm long, not secund; phyllary apex sharply acute to obtuse-angled with a thickened apiculum, not markedly involute, lamina relatively thick, usually with evidently sunken punctate glands, without superficial glands; florets 7-10 (-12); basal and lower cauline leaves 4-9 (-12) mm wide, quickly reduced in width and length distally
                                                                                      41 Involucres 6-10 mm; florets (6-) 7-13 (-17); corolla tubes internally pilose; pappus bristles as long as the corolla tubes (shorter in some populations of L. helleri).
                                                                                           43 Pappus either 0.5 as long as the corolla tube or longer; plants usually < 4 dm tall; [restricted to high elevation areas near Grandfather Mountain NC (and Roan Mountain?)]
                                                                                           43 Pappus about as long as the corolla tube; plants usually > 4 dm tall; [in high elevation areas in w. NC, as well as in mid to lower elevation sites from nw. NC northwards through w. VA and e. WV]
                                                                                             44 Stems glabrous to sparsely or moderately pilose; heads densely arranged, on internodes (1-) 2-5 (-7) mm; peduncles 0-10 (-17, -80 in proximal part of capitulescence) mm; involucres (7-) 8-10 mm, phyllaries in (3-) 4-5 (-6) series
                                                                                                   47 Lower stem leaves with slender petioles and blades elliptic to lance-elliptic, the blades (8-) 11-22 (-27) mm wide (bracts subtending proximal heads 2+ mm wide, grading gradually from distal cauline leaves); phyllary apices usually acuminate to acute, rarely obtuse
                                                                                                          50 Leaves or leafy bracts 8-20 (-25) below the heads, cauline usually abruptly reduced above the basal; florets 19-33 per head; [of the Central and Southern Appalachians]
                                                                                                          50 Leaves or leafy bracts 20-85 below the heads, usually continuing relatively even-sized upward above the basal; florets ca. 30-80 per head; [of WV and PA northward]
                                                                                                     48 Heads usually sessile, less commonly subsessile on peduncles 1-8 mm (rarely more); at least outer phyllaries usually reflexing; florets 11-26 (-30) per head; corolla tubes pilose within.
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