Three New Species of Flourensia (Asteraceae-Heliantheae) From South America

Abstract

Three new species of Flourensia (Asteraceae-Heliantheae) from South America are described: F. peruviana Dillon and F. polycephala Dillon from central and southern Peru respectively; and F. blakeana Dillon from northcentral Argentina. The genus Flourensia is represented by at least four species in Peru, two of these described for the first time within this paper. Flourensia macrophylla Blake is represented by scattered populations in valleys of various rivers draining into the Pacific along the western slope or Cordillera Occidental from northern to central Peru (2,500-3,500i m). Flourensia angustifolia (DC.) Blake is found in intermontane valleys associated with the tributaries of the Rio Perene and Rio Huallaga in the Cordillera Central (1,700-3,300 m). Flourensia peruviana Dillon and F. polycephala Dillon are distributed in dry sites in valleys with eastern drainage from southcentral and southern Peru. Flourensia heterolepis Blake is represented by scattered populations in the Cordillera Real of southeastern Bolivia (ca. 2,700 m), a distance of ca. 725 km from the southeastern Peruvian taxa. Each species is readily distinguished by a complement of morphological characters and a distinct geographical distribution. The distributional pattern of these taxa corresponds with regions postulated to have undergone a series of humidarid cycles during the Quaternary, which drastically and repeatedly altered vegetation patterns (Vuilleumier, 1971; Simpson, 1975). While it is difficult to accurately determine when and how these taxa attained their present distributions, a rather recent radiation is suggested. A similar pattern of species distribution is exhibited in other taxa occupying various habitats in the Peruvian Andes (Simpson, 1975). An additional example is found in Tecoma (Bignoniaceae) (Gentry, 1979) which has unique taxa in each of the major valleys similarly occupied by different Flourensia species. The following key compares the salient differences between all the Flourensia species of Peru and adjacent Bolivia. Figure 1 illustrates the distribution of these species. la. Leaves shallowly denticulate. 2a. Leaves oval to oblong-oval, the apex obtuse to subobtuse -F. macrophylla 2b. Leaves lanceolate to narrowly-elliptic, the apex acute -F. angustifolia lb. Leaves strictly entire. a. Outer phyllaries 2-3 mm long, the inner 3-5 mm long, all ca. 1.5 mm wide F. peruviana 1 I thank Dr. W. G. D'Arcy for providing the Latin descriptions, and Dr. A. Gentry for reviewing the manuscript. I wish to acknowledge the support of field work by an N.S.F. predoctoral dissertation improvement grant and the N.S.F. Flora of Peru grant. Illustrations were prepared by Elizabeth Liebman, Exhibition Department, Field Museum of Natural History. 2 Botany Department, Field Museum of Natural History, Roosevelt Road at Lakeshore Drive, Chicago, Illinois 60605, U.S.A. ANN. MISSOURI BOT. GARD. 68: 105-111. 1981. 0026-6493/81/0105-011 1/$0.85/0 This content downloaded from 157.55.39.235 on Fri, 07 Oct 2016 06:03:54 UTC All use subject to http://about.jstor.org/terms 106 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 68 A X . * Flourensia macrophylla