A New Combination in Vernonia (Compositae: Vernonieae)

This report presents a new combination for a BrazilianVernonia.     

Revision of Vernonia Series Flexuosae (Compositae: Vernonieae)

SeriesFlexuosae consists of eight closely related species. The taxa are collectively unique in their morphology and share similar flavonoid compounds. They range from south-central Brazil southwest into Bolivia, Paraguay, Uruguay and Argentina. The eight species are keyed, described and mapped and synonymies are provided.     

A revision of Vernonia series Buddleiifoliae (Compositae: Vernonieae)

SeriesBuddleiifoliae of the genusVernonia of southeastern South America consists of 18 species which are keyed, described, discussed and mapped.Vernonia goiasensis is proposed as a new name, whileV. wasshausenii andV. monocephala subsp.irwinii are described as new taxa, and V.asteriflora subsp.kuntzei is presented as a new combination.     

A systematic study of the Vernonia leopoldi complex (Compositae — Vernonieae)

A systematic study of the Vernonia leopoldi complex was undertaken with the objective of determining the taxonomic status of the species involved within this group. TWo species, i.e. Vernonia leopoldi and V. bipontini have been recognized as distinct based on evidence from morphological studies accompanied by field observations and anatomical studies (particularly trichomes and petioles). Both species have 2n = 36 (first reports). Three new varieties have been recognized within V. bipontini , namely var. bipontini , var. gonderensis and var. caccaensis . A lectotype is selected for V. leopoldi .     

A New species of Vernonia (Compositae) from Ecuador

Vernonia giannasii, a new species from Ecuador, is described and illustrated.     

Two new species of Vernonia (Asteraceae: Vernonieae) from Panama

Two new species,Vernonia cocleana andV. chiriquiensis, are described from Panama. These endemic species are distinct from those in Central America and most closely resemble taxa in the West Indies and Argentina, respectively. These taxa are described and illustrated; a key is provided to the Panamanian species ofVernonia.     

Two new species of Vernonia (Asteraceae: Vernonieae) from Peru

Two new species,Vernonia sagasteguii andV. paucartambensis, from Peru are described, illustrated, and their relationships discussed.     

Chromosome Numbers and Karyotypes of Species of Vernonia sect. Lepidaploa (Asteraceae: Vernonieae)

Vernonia is the largest genus of the tribe Vernonieae (Asteraceae) and comprises more than 1,000 species. In the present study we explore chromosome number and karyotype variation of eight species treated within different subsections of the section Vernonia sect. Lepidaploa. We aimed to explore if these data support the recognition of a single large genus (sensu Baker) or favor its splitting into 22 small genera (sensu Robinson). The species were collected in ??cerrado??, rupicolous and disturbed areas in the states of S?o Paulo and Minas Gerais, Brazil. Chromosome numbers varied from 2n?=?32 to 60. Most chromosomes were small, and the karyotype analysis revealed a predominance of metacentric and some submetacentric chromosomes. The karyotype symmetry in Vernonia was moderate (TF% 32.2 to 45.9), with the most symmetrical karyotype observed in V. rubriramea. The results obtained here did not conclusively support any of the taxonomic proposals for Vernonia due to the absence of distinctive or characteristic karyotype patterns for any of the taxonomic groupings, i.e., sections and subsections (sensu Baker) or new genera (sensu Robinson). Nevertheless, a tenuous relationship was observed between the chromosome numbers reported in the literature, those recorded here, and the taxonomic alterations suggested by Robinson for the genera Lessingianthus, Chrysolaena, and Vernonanthura that were originally part of Vernonia sensu Baker.     

Lophate sculpturing of Vernonieae (Compositae) pollen

Vernonieae (Compositae) taxa Vernonia and Elephantopus were examined by scanning (SEM) and by transmission electron microscopy (TEM). All pollen grains of Vernonia have a subechinolophate sculpturing consisting of a wrinkled net-like ektexine delineating a system of thickened and randomly meandering ridges and corresponding valleys. Ektexine on the ridges radiates from near mid-regions of massive, individual columellae that terminate in sharp spines approximately 4.5 μm above the ektexine surface. Less massive secondary columellae without apical protrusions support the ektexine net in the spine areas. In the valleys, the ektexine is markedly depressed. Removal of the net by freeze-fracture exposes an exine surface that is clearly imprinted with distinctive lophate features. Elephantopus pollen is echinolophate and extends the morphological range for this little studied genus. Lophae are the thickened equivalents of ektexine tecta and represent the highly anastomosing and intertwined rod-like elements of forked distal parts of densely clumped, massive columellae. Lophae surfaces contain rare punctations that are randomly scattered among blunt spinules ranging from approximately 0.3 to 1.5 μm in height. It is clear that only one sculpture pattern, lophate, characterizes Vernonieae pollen and that it embraces two forms, subechinolophate and lophate. Of the two structural patterns in the Compositae, caveate and noncaveate, subechinolophate sculptured Vernonia pollen is noncaveate. Elephantopus pollen is also noncaveate but more generalized than Vernonia.     

Cytotaxonomic analysis of South American species of Vernonia (Vernonieae: Asteraceae)

Chromosome numbers in 48 populations belonging to 31 species of Vernonia from South America have been determined. First chromosome counts are reported for V. propinqua var. canescens (2 n = 20), V. sceptrum (2 n = 80), V. rufogrisea (2 n = 32), V. heringeri (2 n = 32), V. hovaefolia (2 n = 64), V. hystricosa (2 n = 128), V. obtusata (2 n = 64), V. pseudoincana (2 n = 32), V. rubricaulis var.◊ australis (2 n = 64) and V. rugulosa (2 n = 30). The basic chromosome numbers x = 10, 14, 15, 16 and 17 were confirmed for New World species of Vernonia . Together with previous records, these numbers suggest that the evolution of Vernonieae has occurred through a combination of polyploidy and aneuploidy. Taxonomic implications of certain counts are also discussed.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 401–408.     

Townsendia gypsophila (Compositae: Astereae): a new species from northern New Mexico

Townsendia gypsophila, a new species from Sandoval Co., New Mexico, is described and illustrated. It is a narrowly distributed obligate gypsophile closely related toT. fendleri andT. incana. It overlaps the ranges of the two taxa at the edge of their distributional limits in New Mexico.     

Philactis fayi (Compositae) : A new species from Mexico

The new species is the fourth member of the genus. Morphologically, it is most closely allied toP. liebmannii, but there are ample qualitative and quantitative differences between them. The chromosome numbers ofP. liebmannii andP. nelsonii are 2n = 56 whileP. zinnioides is 2n = 84.Philactis fayi is 2n = 28 and is considered to represent the diploid complement that was probably involved in the production of the other species through hybridization and chromosome doubling.