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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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Galinsoga Ruiz & Pavon
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PlaceOfPublication
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Fl. Peru Prodr. 110. tab. 24. 1794.
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Note
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LECTOTYPE: G. parviflora Cav.
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Synonym
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XWiborgia Roth, Catal. Bot. 2: 112. 1800, nom. rejic. not Viborgia Moench 1794, nom. rejic., nor Wiborgia Thunberg 1800, (Leguminosae), nom. cons. TYPE: W. acmella Roth. Galinsogea Attributed to Ruiz & Pavon in Willd., Sp. P1. 3: 2228. 1803. Orthographic variant of Galinsoga Ruiz & Pavon. Vigolina Poiret in Lam., Encycl. Meth. 8: 613. 1808. TYPE: V. acmella (Roth) Poir, substitute name for Wiborgia Roth, nom. rejic. Galinsogaea Attributed to Ruiz and Pavon in Zucc., Flora 4: 612. 1821. Orthographic variant of Galinsoga Ruiz & Pavon. Vargasia DC., Prodr. 5: 676. 1836, not Bertero ex Spreng. 1825. TYPE: V. caracasana DC. Stemmatella Wedd. ex Benth. in Benth. & Hook., Gen. P1. 2: 193. 359. 1873. TYPE: S. congesta Wedd. ex 0. Hoffm.
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Description
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Annual herbs, erect, decumbent or procumbent; stems 0.1-6 dm tall, often rooting at the lower nodes, branching, striate, green, reddish-green or red, sparsely to densely pubescent with multicellular trichomes. Leaves opposite, petiolate or sessile, entire to dentate-serrate, often ciliate, narrowly oblong to broadly ovate, glabrate to densely pubescent, with 3 principal veins, the bases connate around the stem. Inflorescences loose to congested cymose clusters of heads; peduncles slender, strigose and hispid-pilose, often with glandular capitate trichomes inter- mixed, axillary or terminal. Heads radiate or discoid, 3-8 mm tall, 3-20 mm wide, campanulate; involucral bracts biseriate, imbricate, 1-3 smaller, ovate outer bracts, deciduous or persistent, glabrous or sparsely pilose, the inner bracts more broadly ovate, each deciduous with 2-3 attached adjacent paleas enclosing a ray floret or not, 3-5-nerved, green or with light to dark red-purple tips, glabrous or pilose, slightly to strongly convex, the margins minutely laciniate, ciliate, or entire; receptacle convex to conical, 0.4-3.8 mm tall, 0.7-2.2 mm wide; paleas scarious, linear or narrowly to broadly lanceolate-oblanceolate, entire to deeply trifid, the margins minutely laciniate, sometimes purple-tipped, deciduous or the innermost paleas persistent; ray florets fertile, 3-5 or 8-10, the corolla white, pink, reddish- purple, the ligule wanting or quadrate to oblong, shallowly to deeply trifid, 0.5-7 mm long, 0.3-7 mm wide, the lobes subacute to obtuse, occasionally bilabiate, the tube pubescent, the style bifid with recurved branches, obtuse to acute; disc florets numerous, fertile, perfect or a single outer row of disc florets pistillate, the corolla tubular to campanulate, yellow, yellow-green or red-purple above with yellow below, 1.2-2 mm long, deciduous, lobes 5, acute, erect or reflexed, the limb hirtellous or glabrous, the tube short and pubescent, the anthers with ovate appendages, sagittate at the base, the style branches recurved, acute. Ray achenes turbinate, often compressed, glabrous to hispidulous, black, pappus coroniform or like that of the disc achene but usually shorter and present only on the side of the achene toward the interior of the head, sometimes wanting; disc achenes narrowly turbinate, subterete to somewhat angular, glabrous to hispidulous black, pappus of 10-20 linear-lanceolate, ovate to obovate, apically obtuse to acuminate or aristate scales with fimbriate, ciliate, or laciniate margins, or pappus coroniform or wanting. Chromosome number x = 8
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Habit
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herbs
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Distribution
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Galinsoga is a New World genus of about 16 species.
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Note
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Galinsoga urticaefolia (H.B.K.) Benth. and G. parviflora Cav. have become established as weeds in temperate areas world-wide. The remaining species are restricted in distribution to Mexico, Central America and South America. The species of Galinsoga are all very similar but may be distinguished by habit, leaf type, and features of the heads, such as ligule shape and size, type of pappus when present and shape of the paleas. The genus Galinsoga may be distinguished from the other genera in the subtribe Galinsoginae by a combination of characters including, erect stems, generally small head size, white to purple ligules, the usual presence of 5 ray florets per head, and the usual enclosure of each ray floret in an ovate involucral bract and 2-3 adjacent scarious paleas. These structures: ray floret, involucral bract, and paleas, fall from the head as a single unit.
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Reference
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St. John, H. & D. White. 1920. The genus Galinsoga in North America. Rhodora 22: 97-101. Thellung, A. 1916. tVber die in Mittleuropa vorkommenden Galinsoga-Formen. Allg. Bot. Zeitschr. Syst. 21: 1-16.
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