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(Last Modified On 6/17/2013)
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(Last Modified On 6/17/2013)
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Genus
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Sigesbeckia L.
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PlaceOfPublication
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Sp. P1. 900. 1753
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Note
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TYPE: S. orientalis L.
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Synonym
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Siegesbeckia sensu auct., not L.
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Description
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Mostly erect, branching, annual herbs, a few species procumbent or scapose; stems mostly with erect, multicellular hairs, these often gland-tipped; roots mostly fibrous. Leaves opposite, simple, mostly ovate or elliptic, entire or serrate, viscid-pubescent with weak, spreading multicellular, often gland-tipped hairs, the surface sometimes glandular; petioles mostly winged, sometimes basally auriculate or nearly connate-perfoliate, the leaves near the inflorescence smaller, sessile. Inflorescence an open, several-many-flowered panicle; peduncles with prominent multicellular, often glandular hairs; bracts foliaceous; unpaired, scale- like bractlets often present on the pedicels. Heads mostly radiate, small; involucral bracts of 2 dissimilar series, the 5 outermost lanceolate to linear-spathulate, apically rounded, mostly copiously stipitate-glandular, the stipes stout and the glands conspicuous, opaque, the innermost as many as the ray flowers, ovate, apically deltoid to acuminate, stipitate-glandular, enveloping the ovaries of the ray florets; paleas ovate, scarious, apically stipitate-glandular, enveloping the disc florets; receptacle conical, small; ray florets 5-15, rarely lacking, the corolla yellow, the tube forming half the length, sometimes cobwebby-pubescent, the limb broad, apically sinuate-dentate or bifid, the style branches short, the ovary fertile, asymmetrically fusiform-lenticular, the carpopodium somewhat ventral, pappus wanting; disc florets few to numerous, the corolla with the tube making up half the length, sometimes pubescent, the limb campanulate, angled with 5 deltoid lobes, the anthers yellow or green, with ovate, discrete-appearing apical appendages, basally auriculate, the filaments inserted high in the corolla tube, mostly not flexing in development or anthesis, the style branches somewhat flattened, cuneiform, dorsally pilose at the broadest point, the style base not expanded but articulated with the umbonate ovary apex, the ovary fertile, slightly compressed laterally with a prominent carpopodium, the apex conical with a cylindrical umbo; pappus wanting. Achenes black, minutely striate, curved, plump, sometimes strongly angled, square or ovoid in cross section; carpopodium indistinct; pappus wanting.
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Habit
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herbs
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Distribution
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Sigesbeckia includes about 9 species of warm parts of both the New and Old Worlds.
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Note
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The glandular-stipitate, narrow outer series of involucral bracts are a good feature for recognition. The paleas become indurated in fruit, enveloping the achene but ultimately releasing it.
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Reference
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Humbles, J. E. 1972. Observations on the genus Sigesbeckia. L. Ci. & Nat. 13: 3-19. McVaugh, R. & C. Anderson. 1972. North American counterparts of Sigesbeckia orientalis (Compositae). Contr. Univ. Michigan Herb. 9: 487-493.
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