Juncus pallescens Lam.

  • Authority

    Balslev, Henrik. 1996. Juncaceae. Fl. Neotrop. Monogr. 68: 1-167. (Published by NYBG Press)

  • Family

    Juncaceae

  • Scientific Name

    Juncus pallescens Lam.

  • Type

    Type. Argentina. Buenos Aires, 1767, Commerson s.n. (holotype, P!; isotype, P!).

  • Synonyms

    Juncus dombeyanus J.Gay & Laharpe, Juncus dombeyanus var. typicus Buchenau, Juncus commixtus Steud., Juncus proximus Steud., Juncus fernandezianus Steud.

  • Description

    Species Description - Perennial, cespitose herbs, 20-45 cm tall. Rhizome densely branching, 1.5-2.5 mm diam., with few, small, scariose scales. Culms erect, 0.8-2 mm diam., terete, smooth. Cataphylls 0-2 to each culm, to 5 cm long, inconspicuous. Foliar leaves 2-3 basal and 0-1 cauline to each culm, 10-25 cm long; sheaths 2-7 cm long with scariose margins terminating in two 1.5-3.5 mm long, rounded auricles; blades 1.5-2 mm diam., round to elliptic in x.s., septate but sometimes inconspicuously so. Inflorescence decompound, anthelate, 1.5-10 x 1.5-4 cm, flower heads (l-)3-10(-20), globose at maturity, 0.5-1 cm diam., (4-)8-20-flowered, castaneous, ultimate head bearing branches more than 0.45 mm diam. Lower inflorescence bract 1-5 cm long, shorter than the inflorescence, resembling foliar leaves or scalelike; distal bracts shorter; floral bracts acuminate, ca. 3 mm long, scariose, whitish, usually contrasting the tepal color. Tepals subequal, 3-4.5 mm long, lanceolate, acuminate, robust, rigid, outer tepals concave and scariose towards the margin, inner tepals flat with distinct scariose margin. Stamens usually 6 or rarely 3, 1-2 mm long; anthers 0.5-0.9 mm long, usually about ½ as long as the filaments. Capsule ellipsoid to obovoid, truncate to bluntly acute, 3-lobed to trigonous, (2.2-)2.5-3 x 1.2-1.3(-1.6) mm, green at the base, brown at the apex, glossy, unilocular. Seeds broadly ellipsoid, conspicuously apiculate, 0.3-0.4 x ca. 0.2 mm, reticulate, yellowish brown with a hyaline outer seed coat.

  • Discussion

    In Ecuador and N Peru, J. pallescens has few flower heads, often less than seven, but to the S and in E South America this does not hold true.

    Juncus pallescens Lamarck has been known in the herbaria and in the literature as Juncus dombeyanus J. Gay ex Laharpe. In the protologue of J. pallescens (Lamarck, 1789), its North American occurrence is documented by two literature citations, and its South American occurrence by reference to a specimen {Commerson s.n., “Buenos-Ayres”). This latter collection is preserved with two sheets, one in the Lamarck herbarium at P, and one in the general herbarium at P, both of them with the annotation "Juncus pallescens” in Lamarck’s hand. Since these are the only specimens cited, they are type specimens. The holotype in the Lamarck herbarium is juvenile and difficult to identify, but the isotype in the general herbarium is mature. The exact locality of the collection is uncertain because the isotype also bears, in addition to “Buenos-Ayres,” the annotation “promotorium Montevideo” (= Cerro de Montevideo).

    E. Meyer (1822) placed the North American Juncus acuminatus Michaux in synonymy of J. pallescens. Laharpe (1825) argued that the specimen of J. pallescens in the Lamarck herbarium was too juvenile to serve as the basis for a name, and he placed the name in synonymy of J. acuminatus even if he knew that the South American specimens in the Lamarck herbarium belonged to what he called J. dombeyanus. By emphasising Lamarck’s (1789) references to literature dealing with North American plants, and by paying less attention to specimens, the name J. pallescens became attached to the the North American J. acuminatus, but as a synonym because of its vague definition. Later North American workers, starting with Engelmann (1866), discarded the name because it was based on a South American specimen. Buchenau (1879) realised that J. pallescens belonged to a South American taxon, but he placed it as a “Sammel-Typus” for J. microcephalus and J. dombeyanus, because he was not sure to which of the two taxa it belonged. Later, Buchenau (1890, 1906) cited the name as a synonym of both J. microcephalus and J. dombeyanus. Now that the well-developed isotype with Lamarck’s annotation is known, J. pallescens Lamarck must replace J. dombeyanus J. Gay ex Laharpe. “Juncus punctorius Lamarck” (1789) was cited as a synonym of J. dombeyanus by Laharpe (1825) and Buchenau (1890, 1906). This name was published not by Lamarck but by Linnaeus filius (1781), and it belongs to a South African plant. Lamarck (1789) did, however, cite a collection of Dombey’s from Lima, Peru, under J. punctorius. This specimen happens to be the type of J. dombeyanus J. Gay ex Laharpe, and this coincidence led to the misleading citations.

    The specimens of Juncus dombeyanus J. Gay ex Laharpe cited in the protologue are from “Montevideo” {Dombey s.n.) and “Buenos-Ayres” {Commerson s.n.). One specimen at P with the annotation “Juncus Dombeyanus N.” in J. Gay’s hand is the holotype since Laharpe assigns this name to J. Gay. The specimen, however, bears the locality “Perou” rather than “Monte-Video,” as cited in the protologue. Since Dombey never was in Montevideo, the citation in the protologue must be wrong. The other specimens (Buenos-Ayres, Commerson s.n.) are “cotypes” and happen to be isotypes of Juncus pallescens Lamarck at the same time.

  • Distribution

    Juncus pallescens occurs in the Andes from central Ecuador to S Chile and in E South America from Rio Grande do Sul in Brazil to Buenos Aires in Argentina. In Ecuador, Peru, and Bolivia it grows at elevations of 1900-3600 m, often in disturbed areas but also in natural Sphagnum bogs and edges of páramo lakes.

    Ecuador South America| Azuay Ecuador South America| Cañar Ecuador South America| Galápagos Islands Ecuador South America| Imbabura Ecuador South America| Loja Ecuador South America| Pichincha Ecuador South America| Peru South America| Ancash Peru South America| Cajamarca Peru South America| Huancavelica Peru South America| Huánuco Peru South America| Junín Peru South America| La Libertad Peru South America| San Martín Peru South America| Bolivia South America| Chuquisaca Bolivia South America| Cochabamba Bolivia South America| La Paz Bolivia South America| Paraguay South America| Central Paraguay South America|