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(Last Modified On 6/18/2013)
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(Last Modified On 6/18/2013)
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Species
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Pectis prostrata Cav.
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PlaceOfPublication
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Icon. Descr. P1. 4: 12. 1797.
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Note
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TYPE: Grown from seed at Royal Botanical Garden of Madrid, 1795 (holotype not located at MA; F probable isotype, cultivated at Madrid from seed collected by Nee in Queretaro).
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Synonym
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Pectis costata Ser. & Merc. ex DC., Prodr. 5: 100. 1836. TYPE: Cuba, Sagra s.n. (not seen). Pectis prostrata var. urceolata Fern., Proc. Amer. Acad. Arts 33: 68. 1897. TYPE: Mexico, Chihuahua, Hacienda San Jose, 1885, Palmer 53 (GH, holotype). Pectis urceolata (Fern.) Rydb., N. Amer. Flora 34: 197. 1916. Pectis multisetosa Rydb., N. Amer. Flora 34: 198. 1916. TYPE: Guatemala, Santa Rosa, Chupadero, 1892, Heyde & Lux 4232 (NY, holotype).
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Description
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Prostrate to ascending, much branched, often mat-forming, fibrous-rooted, annual herbs; stems several to many from the base, leafy, terete or round-angled, often purplish, diffusely much branched, pubescent in lines. Leaves linear to narrowly oblanceolate, 1-3 cm long, 1.5-5 mm wide, obtuse, mucronate, marginally ciliate sometimes to above the middle with 4-12 pairs of bristles, scaberulous on the margins, villous-ciliolate toward the base, otherwise glabrous, densely punctate on the pale undersurface with scattered, tiny round glands. Inflorescence of congested cymose clusters; peduncles 1-2 mm long, or heads sessile. Heads radiate; involucres cylindrical, ellipsoid or campanulate, 6-7 mm long, 3 mm wide, the bracts 5, oblong to obovate, obtuse to emarginate with spreading tips, imbricate, indurate-keeled to the tip, bowed out toward the middle, gibbous basally, glabrous, punctate in submarginal rows and sometimes also along the midrib with tiny elliptical glands; ray florets 5, the corollas bright yellow, 3.5-4 mm long, scarcely exceeding the involucres, spreading, but in dried specimens apparently ascending, glabrous, the slender tube ca. 1 mm long, the ligule narrowly ovate but often inrolled and appearing narrower; disc florets 6-15, the corollas yellow, 2.5 mm long, biliabiate, glabrous, the tube narrow, 0.7-1 mm long, the anthers 0.8 mm long with short, truncate appendages, the style branches scarcely exceeding the corolla lobes. Fruit consisting of involucre and enclosed achenes which fall together at maturity; achenes black, narrowly clavate, obscurely many-ribbed, 3-3.7 mm long, strigose to villous in lines; carpopodium small; pappus of 3-5 thin, whitish, lacerate-margined, long-acuminate scales 2-2.5 mm long. Chromosome number n = 12
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Habit
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herbs
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Distribution
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Pectis prostrata is apparently a recent introduction into Panama. Although the species occurs naturally from the southern United States to northern South America, it was not collected in Panama until 1969.
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Note
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It is known in Panama only from disturbed sites in the Canal Zone. Pectis prostrata is a common roadside weed through most of its range, and can be expected to spread along roads and other disturbed sites in Panama. Fortunately it does not become a nuisance in cultivated areas. Pectis multisetosa, described by Rydberg from Guatemalan material, is a name that has been applied to a large-headed form of P. prostrata common in Central America. Other than in number of flowers, these plants do not differ significantly from typical P. prostrata. Because of intergradation in other areas of Central America, recognition of P. multisetosa as a species distinct from P. prostrata is not warranted. Further study may necessitate the recognition of these plants at the varietal level. Both the large-headed and the smaller-headed forms of P. prostrata have been collected in Panama.
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Specimen
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CANAL ZONE: Curundui, D'Arcy 6102 (MO); Tyson & Lazor 5432 (FSU, MO). Albrook, Tyson & Lazor 6015 (FSU).
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