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Published In: Journal de Physique, de Chimie, d'Histoire Naturelle et des Arts 88: 202. 1819. (Mar 1819) (J. Phys. Chim. Hist. Nat. Arts) Name publication detailView in Biodiversity Heritage Library
 

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5. Tribe Eupatorieae Cass.

(King and Robinson, 1987)

Plants annual (in Ageratum) or perennial herbs (shrubs elsewhere), sometimes from a woody rootstock or corm, occasionally twining climbers, the sap not milky. Stems not spiny or prickly. Leaves alternate, opposite, or whorled, sometimes also in a basal rosette, sessile to long-petiolate, not spiny or prickly. Leaf blades entire to pinnately dissected, the venation mostly pinnate, with 1 or 3(–7) main veins. Inflorescences terminal or less commonly axillary panicles, spikes, or racemes, rarely appearing as solitary or clustered axillary heads. Heads discoid. Involucre of 2 to several series of bracts (1 series in Mikania), these overlapping, of more or less equal to strongly unequal lengths, not spiny or tuberculate. Receptacle flat to slightly convex, less commonly conical, naked (chaffy elsewhere). Disc florets all perfect, the corolla white, pink, or purple to nearly blue, the 5 short or less commonly long lobes spreading to ascending. Pappus most commonly of usually numerous capillary bristles, less commonly of relatively few scales or awns, more or less persistent at fruiting. Stamens with the filaments not fused together or fused into a short tube toward the base, the anthers fused into a tube, each tip with a flattened appendage, each base truncate or broadly rounded. Style branches usually not flattened, each with a short stigmatic line along each inner margin, the sterile tip elongate, usually with dense, minute papillae. Fruits monomorphic, mostly several-angled or several-ribbed in cross-section, oblong to slightly wedge-shaped in profile, not beaked. About 170 genera, about 2,400 species, nearly worldwide, but most diverse in the New World.

The modern classification of genera of Eupatorieae largely has been the work of Robert Merrill King and Harold Robinson (both then at the Smithsonian Institution). Starting with a lengthy series of morphological taxonomic studies published over more than two decades and culminating in a comprehensive book-length monograph of the tribe (King and Robinson, 1987), the generic classification of the tribe is among the most thoroughly researched projects in the family. Subsequent molecular studies (Schilling et al., 1999; Schmidt and Schilling, 2000; Ito et al., 2000a, b) have largely supported King and Robinson’s insightful taxonomic observations of morphological and anatomical details. As has been the trend in other tribes of Asteraceae, these studies have resulted in the dissection of the large, polymorphic traditional genus Eupatorium into a series of smaller, more homogeneous genera, four of which occur in Missouri.

 

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1 1. Stems twining; heads with 4 involucral bracts, these more or less equal in size ... 57. MIKANIA

Mikania
2 1. Stems not twining (but sometimes reclining on other plants in Fleischmannia); heads with more than 4 involucral bracts, these of unequal lengths

3 2. Leaves mostly in well-separated whorls of 3–7, the uppermost leaves sometimes opposite or alternate ... 54. EUPATORIUM

Eupatorium
4 2. Leaves opposite or alternate, the internodes well spaced or sometimes short and the crowded leaves then appearing more or less indefinitely whorled

5 3. Stem leaves alternate but sometimes so numerous and dense as to appear indefinitely whorled; fruits finely 10-nerved or 10-ribbed

6 4. Basal leaves absent at flowering or when rarely present the basal leaves about as large as or smaller than the lower and median stem leaves; inflorescence a flat-topped or rounded panicle (in poorly developed plants sometimes reduced to few stalked clusters of heads), or appearing as a leafy panicle with racemose branches ... 52. BRICKELLIA

Brickellia
7 4. Basal leaves often present at flowering, these and the adjacent lowermost stem leaves the largest on the plant; inflorescence an unbranched terminal spike or spikelike raceme, sometimes leafy and the lowermost heads then appearing axillary ... 56. LIATRIS

Liatris
8 3. Stem leaves opposite, mostly well spaced; inflorescence a broad panicle (in poorly developed plants sometimes reduced to a few umbellate clusters of heads) or (in Eupatorium capillifolium) appearing as a leafy panicle with numerous ascending, spicate branches; fruits 3–5-angled or 3–5-ribbed (but 10-ribbed in Brickellia)

9 5. Corollas pink to purple or lavender-blue (note that rarely isolated individuals with white flowers may be found scattered within populations of plants otherwise with pigmented corollas)

10 6. Pappus of 5(6) scales; plants annual ... 51. AGERATUM

Ageratum
11 6. Pappus of numerous capillary bristles; plants perennial

12 7. Receptacle conical; florets 35–70 per head; plants with rhizomes ... 53. CONOCLINIUM

Conoclinium
13 7. Receptacle flat or slightly convex; florets 13–25 per head; plants without rhizomes ... 55. FLEISCHMANNIA

Fleischmannia
14 5. Corollas white or cream-colored, sometimes appearing pale gray; leaf blades variously linear to triangular-ovate

15 8. Leaves sessile or short-petiolate ... 54. EUPATORIUM

Eupatorium
16 8. Leaves long-petiolate (petioles at least 1/3 as along as the blades)

17 9. Leaf blades linear to lanceolate, narrowly triangular, or narrowly elliptic or, if broader in outline, then pinnately dissected into narrowly linear lobes ... 54. EUPATORIUM

Eupatorium
18 9. Leaf blades triangular-ovate, unlobed

19 10. Leaf blades mostly broadly angled or broadly rounded at the base; fruits 5-angled or 5-ribbed ... 50. AGERATINA

Ageratina
20 10. Leaf blades mostly truncate to cordate at the base; fruits finely 10-nerved or 10-ribbed ... 52. BRICKELLIA Brickellia
 
 
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