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(Last Modified On 6/18/2013)
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(Last Modified On 6/18/2013)
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Genus
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Dyssodia Cav.
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PlaceOfPublication
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Descr. P1. Dem. 202. 1802.
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Note
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TYPE: Tagetes papposa Vent. Dyssodia papposa (Vent.) Hitchc.
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Synonym
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Willdenowa Cav., Icon. Descr. P1. 1: 61, tab. 89. 1791, not Willdenowa Thunb. 1790. TYPE: Willdenowa glandulosa Cav. Boebera Willd., Sp. P1. 3: 2125. 1804. TYPE: B. chrysanthemoides Willd. nom. illeg. Schlectendalia Willd., Sp. P1. 3: 2125. 1804, nom rejic., Schlectendalia Less. 1830, (Com- positae), nom. cons. TYPE: Willdenowa glandulosa Cav. Adenophyllum Pers., Syn. PI. 2: 458. 1807. TYPE: Willdenowa glandulosa Cav. Thymophylla Lag., Gen. Sp. PI. Nov. 25. 1816. TYPE: T. setifolia Lag. Clomenocoma Cass., Diet. Sci. Nat. 9: 416. 1817. TYPE: Aster aurantius L. Hymenatherum Cass., Bull. Soc. Philom. 1818: 183. 1818. TYPE: H. tenuifolium Cass. Lebetina Cass., Dict. Sci. Nat. 25: 395. 1822. TYPE: L. cancellata Cass. Rosilla Less., Syn. Gen. Comp. 245. 1832. TYPE: R. lutea Less. Syncephalantha BartI., Ind. Sem. Hort. Goett. 6. 1836. TYPE: S. decipiens Bartl. Gnaphalopsis DC., Prodr. 7: 258. 1838. TYPE: G. micropoides DC. Aciphyllaea (DC.) A. Gray, Mem. Amer. Acad. Arts, n.s. 4: 91. 1849. TYPE: Dyssodia acerosa DC. Lowellia A. Gray, Mem. Amer. Acad. Arts, n.s. 4: 89. 1849. TYPE: L. aurea A. Gray. Comaclinum Scheidw. & Planch. ex Planch., Fl. Serres 8: 19. 1852. TYPE: C. aurantiacum Scheidw. & Planch. Boerbastrum (A. Gray) Rydb., N. Amer. Flora 34: 161. 1915. TYPE: Dyssodia anthemidifolia Benth. Dysodiopsis (A. Gray) Rydb., N. Amer. Flora 34: 171. 1915. TYPE: Dyssodia tagetoides Torr. & A. Gray
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Description
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Glabrous or pubescent annual or perennial herbs or shrubs, often strong- scented; stems few- to many-branched, depressed to erect. Leaves opposite or alternate, simple and entire to deeply pinnatisect or pinnately compound, variously punctate with oil glands. Inflorescence of few to many, solitary or cymosely clustered, sessile or peduncled heads, sometimes condensed into secondary heads; peduncles short to elongate, usually bracteolate. Heads radiate, or less commonly, discoid; involucres cylindric to campanulate, the bracts biseriate, distinct or variously fused, often subtended by an outer series of smaller bracts, variously punctate; receptacle flat to convex, fimbrillate; ray florets fertile, the corollas yellow, orange, red, or white, the ligules small to conspicuous; disc florets perfect and fertile, few to many, the corollas yellow to orange, regular or unequally lobed, the anthers subsagittate basally, the appendages deltoid-acute, the style branches elongate, variously appendaged. Achenes cylindric to obpyramidal, usually angled or ribbed, variously pubescent; carpopodium small, knoblike; pappus of awns, scales, coroniform, or absent. Chromosome base numbers x = 7, 8, 13
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Habit
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herbs or shrubs
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Distribution
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Dyssodia is a mostly North American genus of about 33 species. Except for two taxa with amphitropical distributions, the genus does not reach South America.
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Note
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The primary center of diversity of the genus is Mexico. In Panama, the genus is represented by a single, somewhat anomalous species, Dyssodia montana. According to Strother (1969), Dyssodia is linked through D. montana to the small South American genus, Schizotrichia Benth. Dyssodia montana is also suspected of bridging the gap between Dyssodia and the Mexican genus, Gymno- laena Rydb. (Strother, 1967, 1969). A recent revision by Strother (1969) has provided a much-needed updating of the nomenclature of Dyssodia. The only previous treatments of the genus of any comprehensive nature were those of Hoffman (1894) and Rydberg (1915), the latter complicated by a proliferation of ill-defined genera.
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Reference
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Johnston, M. C. & B. L. Turner. 1962. Chromosome numbers of Dyssodia (Compositae-Tagetinae) and phyletic interpretations. Rhodora 64: 2-15. Strother, J. L. 1967. Taxonomy of Gymnolaena (Compositae: Tageteae). Sida 3: 110-114.
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