Liatris

Perennials, 20–180 cm (corms globose to depressed-ovoid or napiform, sometimes elongated, becoming rhizomes, roots all or mostly adventitious). Stems erect, simple or basally branched. Leaves basal and cauline; alternate; ± petiolate (basal) or sessile (usually appressed to ascending); blades usually 1-nerved, sometimes 3- or 5-nerved, mostly linear to ovate-lanceolate, margins entire, faces often gland-dotted (stipitate-glandular in L. glandulosa). Heads discoid, in corymbiform, cymiform, racemiform, or spiciform arrays. Involucres mostly campanulate to hemispheric or turbinate-cylindric, (2.5–)3–22(–25) mm diam. Phyllaries persistent or tardily falling, 18–40 in (2–)3–7 series, not notably nerved, ovate to elliptic or lanceolate, usually unequal (herbaceous to petaloid, margins often hyaline, often ciliate or irregularly toothed, apices often pink-white). Receptacles flat, epaleate. Florets 3–85; corollas usually lavender to dark magenta or pinkish purple, sometimes white, throats funnelform (lengths 4–6 times diams., externally glanduliferous, glabrous inside or pilose inside near filament insertions, hairs whitish, crisped); styles: bases not enlarged, glabrous, branches linear-clavate (papillate). Cypselae prismatic, 8–11-ribbed, usually hirsutulous to hirtellous-pilose (glabrous in L. oligocephala), usually gland-dotted; pappi persistent, of 12–40 coarsely barbellate to plumose bristles in 1–2 series. x = 10.

Distribution

North America, Mexico, West Indies (Bahamas).

Discussion

Species 37 (37 in the flora).

The globose perennating structures of Liatris have been described as corms and cormoid rootstocks, the elongate ones as rhizomes and penetrating rootstocks. They are here regarded as corms and rhizomes, rather than roots with adventitious buds. New stems may be produced from various lateral points (nodes) of the corms. Some taxa show various stages of transition between globose structures and elongate structures that function like horizontal rhizomes. All other Liatrinae (except perhaps the shrubby Garberia) apparently produce rhizomes with fibrous roots, rather than a taproot.

Selected References

Gaiser, L. O. 1946. The genus Liatris. Rhodora 48: 165–183, 216–263, 273–326, 331–382, 393–412.

Gaiser, L. O. 1950. Chromosome studies in Liatris. I. Spicatae and Pycnostachyae. Amer. J. Bot. 37: 122–135.

Gaiser, L. O. 1950b. Chromosome studies in Liatris. II. Graminifoliae and Pauciflorae. Amer. J. Bot. 37: 414–423.

Gaiser, L. O. 1950c. Chromosome studies in Liatris. III. Punctatae. Amer. J. Bot. 37: 763–777.

Gaiser, L. O. 1950d. Evidence for intersectional field hybrids in Liatris. Evolution 5: 52–67.

Menhusen, B. R. 1963. Variation in the Punctatae Series of the Genus Liatris (Compositae). Ph.D. dissertation. University of Kansas.

Nesom, G. L. and J. M. Stucky. 2004. Taxonomy of the Liatris pilosa (graminifolia) group (Asteraceae: Eupatorieae) Sida 21: 815–826.

Nesom, G. L. 2005. Infrageneric classification of Liatris (Asteraceae: Eupatorieae). Sida 21: 1305–1321.

Lower Taxa

Liatris acidota, Liatris aestivalis, Liatris aspera, Liatris bracteata, Liatris chapmanii, Liatris cokeri, Liatris compacta, Liatris cylindracea, Liatris cymosa, Liatris elegans, Liatris elegantula, Liatris garberi, Liatris gholsonii, Liatris glandulosa, Liatris gracilis, Liatris helleri, Liatris hirsuta, Liatris laevigata, Liatris lancifolia, Liatris ligulistylis, Liatris microcephala, Liatris ohlingerae, Liatris oligocephala, Liatris patens, Liatris pauciflora, Liatris pilosa, Liatris provincialis, Liatris punctata, Liatris pycnostachya, Liatris savannensis, Liatris scariosa, Liatris spicata, Liatris squarrosa, Liatris squarrulosa, Liatris tenuifolia, Liatris tenuis, Liatris virgata

Key

1	Pappi usually of plumose or subplumose bristles (barbellate to subplumose, barbels mostly 0.5–1 mm, in L. acidota and L. ohlingerae)	> 2
1	Pappi usually of barbellate bristles (barbels mostly 0.1–0.4 mm)	> 15
2	Phyllary apices (at least inner) prolonged, ± spreading, ± dilated, petaloid (pink, purplish, white, or yellow)	Liatris elegans
2	Phyllary apices (at least of inner) acuminate, acute, cuspidate, mucronate, obtuse, rounded, rounded-acuminate, or truncate (seldom notably spreading, not dilated or petaloid)	> 3
3	Heads in cymiform or corymbiform to subcorymbiform arrays; peduncles (arcuate or ascending-spreading) 20–70 mm	> 4
3	Heads usually in racemiform to spiciform arrays, rarely borne singly; peduncles 0 or 1–10(–25) mm	> 5
4	Involucres cylindro-campanulate, 14–17 × 8–11 mm; phyllary apices usuallyrounded, often mucronate; Texas	Liatris cymosa
4	Involucres hemispheric to campanulate or broadly turbinate, 17–23 × 15–20 mm; phyllary apices usually rounded to obtuse (pappus bristles barbellate tosubplumose); Florida	Liatris ohlingerae
5	Leaves 3–5-nerved; florets 10–60; corollas (lobes adaxially hispid)	> 6
5	Leaves mostly 1-nerved, sometimes 3–5-nerved (L. acidota); florets (2–)3–6(–8) or 8–14(–16); corollas (lobes glabrous)	> 9
6	Phyllaries ± equal (outer usually as long as or longer than inner)	> 7
6	Phyllaries ± unequal (outer shorter)	> 8
7	Heads usually borne singly (each immediately subtended by relatively broad, foliaceous bracts longer than involucres); stems glabrous	Liatris compacta
7	Heads in racemiform to spiciform arrays; stems glabrous or puberulent-villous	Liatris squarrosa
8	Stems hirsute to piloso-hirsute; phyllary apices (at least inner) acute-acuminate (all usually spreading to reflexed on distal 1/5–1/3, usually without hyaline borders)	Liatris hirsuta
8	Stems usually glabrous; phyllary apices (at least inner) usually rounded, rounded-acuminate, or truncate, often stiffly mucronate (all essentially erect and appressed, usually with narrow hyaline borders)	Liatris cylindracea
9	Heads in loose, spiciform arrays (widely spaced, stems evident); florets 4–6(–8) or 8–14(–16)	> 10
9	Heads in dense, spiciform arrays (closely spaced, stems usually obscured); florets (2–)3–6(–8)	> 11
10	Florets 4–6(–8)	Liatris punctata
10	Florets 8–14(–16)	Liatris bracteata
11	Corms elongate or becoming rhizomes	Liatris punctata
11	Corms globose, subglobose, depressed-globose, or ovoid	> 12
12	Leaves 3(–5)-nerved (bases of basal often fibrous-persistent), cauline abruptly reduced distally (pappus bristles subplumose); coastal plain, Louisiana, Texas	Liatris acidota
12	Leaves 1-nerved (bases not fibrous-persistent), cauline usually gradually or little reduced, sometimes abruptly reduced, distally; inland habitats	> 13
13	Stems stipitate-glandular	Liatris glandulosa
13	Stems glabrous (not glandular)	> 14
14	Phyllaries (11–18) in (4–)5–6 series, mostly oblong-obovate, unequal (inner 7–9 mm), apices obtuse to truncate-rounded (each tipped by thick, often indurate apicula or mucros, lateral veins usually not evident beyond middle or at least on distal 1/3); flowering mostlymid–late Aug(–Oct)	Liatris punctata
14	Phyllaries (6–11) in 2–3 series, oblong-lanceolate to lanceolate-triangular, subequal (inner 11–12 mm), apices acute to acute-attenuate (sometimes with narrow tips, lateral veins usually evident beyond middle, continuingnearly to tips); flowering mid Jul–Aug(–Sep)	Liatris aestivalis
15	Heads borne singly or (2–30) in corymbiform to subcorymbiform arrays	> 16
15	Heads in racemiform to spiciform arrays	> 17
16	Involucres campanulate-turbinate, 10–19(–23) × (8–)10–17(–22) mm; phyllaries in ± 3–4 series, apices mostly long-acuminate (innermost short-acuminate); Alabama	Liatris oligocephala
16	Involucres hemispheric to campanulate or broadly turbinate, 17–23 × 15–20 mm; phyllaries in 6–7 series, apices rounded to obtuse; Florida	Liatris ohlingerae
17	Leaves 3- or 5-nerved	> 18
17	Leaves usually 1-nerved, sometimes 1- (or 3-) nerved	> 22
18	Stems glabrous (often sparsely sessile-glandular, leaf bases not fibrous-persistent); corolla tubes pilose inside	Liatris savannensis
18	Stems glabrous or piloso-puberulent (not glandular, leaf bases fibrous-persistent); corolla tubes glabrous inside	> 19
19	Phyllary apices obtuse to rounded	> 20
19	Phyllary apices acuminate, acute, or acute-acuminate	> 21
20	Basal leaves 6–12(–15) mm wide; Great Plains	Liatris lancifolia
20	Basal leaves (2–)4–10(–20) mm wide; e of Mississippi River	Liatris spicata
21	Phyllary apices acute to acute-acuminate (reflexed to curving-spreading,tips often ± dilated, nearly petaloid); florets (4–)5–8	Liatris pycnostachya
21	Phyllary apices acuminate to acute (erect and ± appressed); florets (2–)3–4(–5)	Liatris acidota
22	Phyllary apices (at least mid and inner) usually acuminate to acute or rounded to rounded-retuse and minutely involute-cuspidate to acuminate or apiculate	> 23
22	Phyllary apices (at least mid and inner) usually obtuse, rounded, or truncate, rarely acute (not rounded-retuse or cuspidate to apiculate)	> 34
23	Phyllaries narrowly triangular, margins without hyaline borders, apices (divergent), usually acuminate to acute; florets 10–12; w Louisiana, e Texas	Liatris tenuis
23	Phyllaries elliptic-oblong, lanceolate, oblong, oblong-lanceolate, oblong-obovate, obovate, ovate, ovate-triangular, or spatulate, margins usually with narrow hyaline borders, apices (erect) acuminate, acute, obtuse-angled, rounded, or rounded-retuse, sometimes minutely involute-cuspidate to apiculate; florets 3–6(–9) or 7–10(–12); mostly e of Mississippi River	> 24
24	Stems glabrous or sparsely pilose	> 25
24	Stems hirtellous (hairs spreading to slightly deflexed) or hirsute, piloso-puberulent, puberulent, strigoso-hirtellous, or strigoso-puberulent	> 29
25	Phyllary apices usually rounded-retuse and minutely involute-cuspidate to apiculate; corolla tubes glabrous inside	> 26
25	Phyllary apices acute, obtuse-angled, or rounded; corolla tubes pilose inside	> 27
26	Stems glabrous or sparsely pilose; basal (and proximal cauline) leaves linear (arising from separated nodes), 1–2(–2.5) mm wide, abruptly or gradually reduced distally, margins usually ciliate proximally, facesgland-dotted	Liatris tenuifolia
26	Stems glabrous; basal leaves (mostly arising from congested nodes) lance-linear to linear, (1–)2–6(–9) mm wide, abruptly reduced distally, margins not ciliate, faces (minutely white-dotted by stomates) weakly, if at all, gland-dotted	Liatris laevigata
27	Heads in racemiform to spiciform (often strongly secund) arrays; involucres (7–)11–15 mm; phyllaries oblong to oblong-oblanceolate;florets 3–6	Liatris pauciflora
27	Heads in racemiform to spiciform (sometimes secund) arrays; involucres (6–)7–9 mm; phyllaries ovate-triangular to oblong or oblong-lanceolate; florets 4–10(–12)	> 28
28	Heads in loose arrays (not secund, internodes 6–20 mm); phyllary apices sharply acute to obtuse-angled, apiculate (apicula thickened, not markedly involute, laminae relatively thick, usually with glands in pits, without superficial glands); florets 7–10(–12); basal and proximal cauline leaves (2–)4–9(–12) mm wide (usuallyabruptly, sometimes gradually, reduced distally)	Liatris virgata
28	Heads in dense arrays (often secund, internodes 1–5 mm); phyllary apices rounded, acuminate to involute-cuspidate (laminae relatively thin, glands superficial at least proximally); florets 4–7(–9); basal and proximal cauline leaves 2–5 mm wide (abruptly or gradually reduced distally)	Liatris cokeri
29	Stems hirsute, puberulent, piloso-puberulent, or strigoso-puberulent	> 30
29	Stems hirtellous (hairs spreading to slightly deflexed)	> 32
30	Corms elongated into rhizomes (irregularly shaped, sometimes with thickened, fibrous roots); involucres 8–10 mm	Liatris garberi
30	Corms globose to elongate; involucres 4–6(–7) mm	> 31
31	Cauline leaves (proximal) usually lanceolate, linear, linear-oblanceolate, or oblanceolate, sometimes narrowly spatulate, 2–8(–10) mm wide (bracts subtending proximal heads to 2 mm wide, abruptly differentiated from distal cauline leaves); phyllary apices usually rounded or obtuse-truncate, rarely acute	Liatris gracilis
31	Cauline leaves (proximal) spatulate (petioles slender, blades elliptic to lance-elliptic), (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	Liatris gholsonii
32	Heads in relatively loose, racemiform to spiciform (often secund)arrays	Liatris pauciflora
32	Heads in dense, spiciform (cylindric) arrays	> 33
33	Heads (rigidly ascending, appressed to rachises and each other, overlapping); phyllary margins usually not ciliolate, apices (erect) acuminate to acute	Liatris chapmanii
33	Heads (spreading to ascending, not strongly overlapping); phyllary margins ciliolate, apices (slightly spreading) acuminate to acute	Liatris provincialis
34	Stems glabrous (sometimes sparsely sessile-glandular, rarely sparsely to moderately pilose in L. pilosa)	> 35
34	Stems hispidulo-puberulent, piloso-puberulent, puberulent, puberulent-villous, strigoso-hirtellous, or strigoso-puberulent	> 39
35	Involucres 5–7(–9) mm; florets 4–5(–6); corolla tubes glabrous inside (pappi: lengthsusually ± 1/2 corollas)	Liatris microcephala
35	Involucres 6–10 mm; florets (6–)7–13(–17); corolla tubes pilose or glabrous (L. ligulistylis) inside (pappi: lengths usually equaling corollas, shorter in some populations of L. helleri)	> 36
36	Stems glabrous (often sparsely sessile-glandular); involucres (8–)9–11(–12) mm diam.; phyllaries: hyaline borders erose to lacerate, (0.2–)0.4–1 mm wide;florets 9–17	Liatris savannensis
36	Stems glabrous or sparsely to moderately pilose (not glandular); involucres 5–8(–10) mm diam.; phyllaries: hyaline borders smooth or erose to lacerate, 0.2–0.4 mm wide; florets (6–)7–13(–17)	> 37
37	Plants 15–55 cm; leaves weakly, if at all, gland-dotted; pappi: lengths 1/3–2/3 or equaling corollas; montane	Liatris helleri
37	Plants 40–120 cm; leaves ± gland-dotted; pappi: lengths ± equaling corollas; coastal plain and piedmont	> 38
38	Stems glabrous or sparsely or moderately pilose; heads in loose to dense arrays (internodes 1–7 mm); peduncles 0 or 1–10(–80) mm; involucres(7–)8–10 mm; phyllaries in (3–)4–5(–6) series	Liatris pilosa
38	Stems glabrous; heads in loose arrays (internodes 2–14 mm); peduncles 0 or 2(–7) mm; involucres 6–8 mm; phyllaries in 3–4(–5) series	Liatris elegantula
39	Involucres 2.5–7 mm diam.; florets 3–12	> 40
39	Involucres (6–)8–15 mm diam. (L. squarrulosa) or 13–22(–25) mm diam.; florets 11–80.	> 42
40	Stems moderately to densely strigoso-hirtellous; peduncles (divergent, arcuate-ascending) 10–25(–30) mm; involucres 5–7 mm diam.; phyllary apices rounded to subtruncate; florets 7–12	Liatris patens
40	Stems piloso-puberulent, puberulent, or strigoso-puberulent; peduncles 0 or (usually ascending) 2–10(–12) mm; involucres 2.5–4(–5) mm diam.; phyllary apices rounded or obtuse to acuminate or acute; florets 3–6(–9)	> 41
41	Proximal cauline leaves usually linear to linear-oblanceolate or oblanceolate, sometimes narrowly spatulate, 2–8(–10) mm wide (proximal floral bracts to 2 mm wide, abruptly differentiated from distal cauline leaves); phyllaryapices usually rounded or obtuse-truncate, rarely acute	Liatris gracilis
41	Proximal cauline leaves spatulate (blades elliptic to lance-elliptic), (8–)11–22(–27) mm wide (proximal floral bracts 2+ mm wide, gradually differentiated from distal cauline leaves); phyllary apices usually acuminate to acute,rarely obtuse	Liatris gholsonii
42	Peduncles usually (5–)8–50 mm, rarely 0; phyllaries (usually erect, rarely spreading-reflexing); florets 30–80 (19–33 in L. scariosa var. scariosa); corolla tubes glabrous or pilose inside	> 43
42	Peduncles usually 0, sometimes 1–8+ (rarely to 30 in L. squarrulosa) mm; phyllaries (at least outer) usually reflexing, sometimes erect; florets 11–30; corolla tubes pilose inside	> 44
43	Phyllary margins: hyaline borders erose to lacerate or irregular; corolla tubes glabrousinside; Great Plains, e slope of Rocky Mountains in United States	Liatris ligulistylis
43	Phyllary margins: hyaline borders none or relatively smooth; corolla tubes pilose orglabrous inside; ne and nc United States, adjacent Canada	Liatris scariosa
44	Phyllaries glabrous (bullate, hyaline borders relatively broad, often erose to lacerate or irregular)	Liatris aspera
44	Phyllaries glabrous or puberulent to puberulent-hirtellous (not bullate, hyaline borders none or relatively narrow, smooth)	Liatris squarrulosa