SYSTEMATICS OF BACCHARIS (COMPOSITAE-ASTEREAE) IN BOLIVIA, INCLUDING AN OVERVIEW OF THE GENUS

摘要

Baccharis (Compositae-Astereae) includes herbaceous perennials, shiubs, vines, and trees It occurs throughout the warmer regions of North America and in Central America, in the West Indies, and in South America from sea level to over 5000 m elevation.The genus is morphologically diverse, and investigation of microcharacters is suggested to be crucial for future taxonomic work. Striking parallel evolution of habit characters was observed in different lineages, e.g., of dwarf procumbent shrubs of thealpine and nival vegetation zone, large shrubs of the cloud forest and ceja vegetation with large, pinnately veined leaves and corymbose ca-pitulescences, and vines of cloud and rain forests at different elevations Baccharis occurs throughout Bolivia, but is most abundant and species-rich at middle and high elevations of the Andes, especially in the Yungas, the Tucuman forest region, and the dry valley regions Some species (e.g., Baccharis dracunculifolia, B tola) are dominant elements of open, high altitude vegetation. The tropical and subtropical regions of Bolivia, on the east slope of the Andes, differ greatly in the composition of their Baccharis flora. The Yungas legion includes many species found also in other tropical regions of the Andes and several species that are endemic to Bolivia and southern Peru. Species occurring in central and southern Bolivia are elsewhere often restricted to the Andes of northwestern Argentina; these regions include a striking number of species that also occur in southeastern Brazil and adjacent areas. Several Yungas-SE Brazil disjunctions suggest a partially natural origin of open vegetation at medium altitudes of the Yungas. The distribution of the different infrageneric groups suggests that the east side of theAndes between northern Bolivia and central Argentina is the original center of radiation for the genus Hybridization was noted for a few species. Except in two cases, hybrids are restricted to areas of sympatry of both parental species andd are often fertile. The Bolivian flora includes 59 species of Baccharis (nearly 1/5 of the genus), including 31 subspecies and varieties; of these 13 species and 10 infraspecific taxa are endemic to the country, Baccharis is here divided into four subgenera and threeadditional unranked groups of unclear affinities; unranked groups are circumscribed within most subgenera. All generic segregates placed in the Baccharid-inae (i.e., Baccharidiopsis, Heterothalamulopsis, Heterothalamus, Pseu4obaccharis, Stephananthus),except Archibaccharis, are included in Baccharis Nine new species are described (B. beckii, B. cana, B. glomerata, B. pumila, B. samensis, B. saxatilis, B. torricoi, B. woodii, B. zongoensis) and ten new subspecific taxa (B. coridifolia subsp, bicolor, B. juncea subsp clavata, B. papillosa subsp, australis, B. papillosa subsp, chaparensis, B. papillosa subsp integrifolia, B. papillosa subsp kessleri, B. papillosa subsp longipedicellata, B. papillosa subsp yungensis, B. subalata var. vargasii, B. tola subsp, fitnbriata) Twelve new combinations are proposed (B, lewisii, B decussata subsp. jelskii, B. genistelloides subsp, crispa, B. linearifolia subsp chilco, B. linearifolia subsp, polycephala, B. pentlandii subsp, sculpta, B. saliens var. solomonii, B.tola subsp. santelicis, B. tola var, chtysophylla, B. tola var, incarum, B. tola var viscosissima, B. trinervis var, debilis), as well eight new combinations (B. aliena, B. caespitosa subsp. procumbens, B. densiflora subsp. perulata, B. psiadioides, B. mfidula, B. salicifolia subsp, calliprinos, B. salicifolia subsp monoica, B. wagenitzii) for taxa not found in Bolivia (Appendix 1). A second appendix lists, with comments, names erroneously reported for Bolivia in the literature All taxa are illustratedand mapped, and keys in English and Spanish are provided.