Monographs Details: Rhynchospora robusta (Kunth) Boeckeler
Authority: Maguire, Bassett. 1972. The botany of the Guayana Highland--part IX. Mem. New York Bot. Gard. 23: 1-832.
Family:Cyperaceae
Description:Distribution and Ecology - Distribution. Widely distributed in tropical America from southern Mexico and the West Indies through the Guianas and Amazonian Basin southwards to Paraguay and adjacent Argentinian State of Misiones. Rather scarce in northern South America. Following are the specimens examined from South America. VENEZUELA. Merida: vicinity of Tabay, margin of Carretera, F.F.Y. 539 (MAR); Bolívar: Gran Sabana, Enemasie to San Raphael, 900 m alt, Maguire 33574 (NY). BRAZIL. Goyaz: [without details,] Gardner 4395 (K); Distrito Federal: Brasília, Pereira 4604 (NY, RB), vicinity of Sobredinho, Prance & Silva 59079 (NY); Minas Gerais: Fazenda S. Jose, Verjão, Mun. S. José de Geribá, Castellanos & Santos 24172 (HB, NY), Serra de S. Antonio, Martius (M), Serra do Espinhaço, 27 km SW of Diamantina, on Road to Gouveia, 1300 m alt, Irwin et al 21977 (NY, UB); São Paulo : Municipio de Moji-Guaçu, Fazenda Campininha, 4 km NNW of Padua Sales, 575— 625 m alt, Eiten & Eiten 1741 (NY), Villa Mariana, Usteri 8 (SP), Butantan near São Paulo, Höhne 491 (SP); Paraná: between Curitiba and Pinhaes, Dusen 8931 (P), Curitiba, Pinhaes, Hatschbach 14731 (K, NY, US); Santa Catarina: Campo Alegre, lower Fazenda of Ernesto Scheide, 900 m alt, L. B. Smith & Klein (NY, US); Rio Grande do Sul: Fazenda B. Velho, Bom Jesus, Rambo 34814 (NY, SI), Municipio de Rio Pardo, Jürgens 67 (B). ARGENTINA. Misiones: Posadas, by La Granja, Ekman 129B (S).

Discussion:

Dichromena robusta Kunth, Enum. Pl. 2: 283. 1837. Type. Sellow (B) from “Brasilia meridionalis.”

Psilocarya robusta (Kunth) Nees, Fl. Brasil. 2(1): 116. 1842. Based on Dichromena robusta Kunth.

Psilocarya robusta Nees var major Nees, FI. Brasil. 2(1): 116. 1842. Type. Sellow (B) from “Brasilia meridionalis.”

Psilocarya robusta Nees var minor Nees, FI. Brasil. 2(1): 116. 1842. Type. Martius (M) from Serra de S. Antonio, Minas Gerais, Brazil.

[.Schoenus pubigerus Schrader ex Nees, FI. Brazil. 2(1): 116. 1842. Invalid name published as a synonym.]

Rhynchospora robusta Böckeler var polyantha Kükenthal, Bot. Jahrb. 75: 171. 1950. Type. Damazio 2195 (B, R) from Cachoeira de Campo, Minas Gerais, Brazil.

Type. Sellow (B) from “Brasilia meridionalis.”

This species may or may not be pubescent. The hairy form of R. robusta can be confused with closely related R. velutina. A sharp difference between the two, however, is seen in the shape of achenes, i e, the achenes of R. robusta are 2 to 2.25 mm long, and their elongated-deltoid style-base is broader than the body of achene with its deeply lobed base embracing the upper half of the achene edges, whereas in R. velutina the smaller achenes are 1.25 to 1.75 mm long, and the depressed-conical style-base is narrower than the body of achene with its shallowly lobed base covering only the apical part of the achene-body. Generally, the plants of R. robusta are much larger than in R. velutina, and are densely hispid on awns of glumes and bracteoles in contrast to glabrous mucroes of glumes and bracteoles in the latter.

Distribution:Mexico North America| West Indies| Guyana South America| Paraguay South America| Argentina South America|