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The taxonomic significance of cypsela features of South American species of Lessingianthus (Vernonieae, Asteraceae) is analysed for the first time and discussed in relation to other genera of the tribe Vernonieae. The morphology of the cypselae of 112 species of the genus were analysed using stereo-, light and scanning electron microscopy (SEM) to evaluate the infrageneric relationships and their reliability as taxonomic markers at a generic level. Characters such as cypsela pubescence, carpopodium structure, crystals and idioblasts on the fruit wall were examined. We established three types of cypsela on the basis of the presence or absence, and type of trichomes. Carpopodium is present in all species of the genus. Crystals are very variable in shape and size, with prismatic (rectangular and hexagonal) and styloid shapes. Idioblasts are present in all of the species, except for two. Cypsela features of Lessingianthus are often widespread in other related genera of Vernonieae. Therefore, these characters are not good taxonomic markers at the genus level, but they are valuable within genera to differentiate related species from one another.

In the present study 16 populations belonging to 13 species of the genus Vernonia Schreb. were examined cytologically. In total, six different chromosome numbers, which represent three basic numbers: x ¼ 10, x ¼ 16 and x ¼ 17, were found. These results include the first chromosome number reports for the following four species:Besides, a new chromosome number was found in V. saltensis Hieron. (2n ¼ 2x ¼ 32), for which only tetraploid populations have been previously recorded. The data obtained in this work, along with the information available from the literature, show that the genus Vernonia in South America is heterogeneous with basic chromosome numbers that range between x ¼ 9 and x ¼ 19. These numbers suggest that a combination of polyploidy and aneuploidy has played an important role in the evolution of the genus.

Mitotic or meiotic chromosome numbers for 42 accessions belonging to 39 species of different genera of Asteraceae were determined. First chromosome counts are reported for one genus ( Gymnocoronis ), 14 species, and one variety. These are as follows: Solidago chilensis var. megapotamica (2 n = 2 x = 18), Chromolaena barbacensis (2 n = 3 x = 30), Chromolaena christieana (2 n = 3 x = 30), Chromolaena hirsuta (2 n = 4 x = 40), Chromolaena verbenacea ( n = 20 II, 2 n = 4 x = 40), Disynaphia multicrenulata (2 n = 2 x = 20), Gymnocoronis spilanthoides var. subcordata (2 n = 2 x = 20), Mikania thapsoides (2 n = 4 x = 68), Stevia commixta (2 n = 2 x = 22), Porophyllum brevifolium (2 n = 4 x = 44), Viguiera rojasii (2 n = 2 x = 34), Pterocaulon angustifolium (2 n = 2 x = 20), Gochnatia haumaniana (2 n = 4 x = 44), Senecio ostenii (2 n = 4 x = 40), Senecio pinnatus (2 n = 8 x = 80), and Lepidaploa amambaia (2 n = 2 x = 28). Chromosome numbers differing from those reported previously in the literature were found in Campuloclinium macrocephalum (2 n = 2 x = 20), Melanthera latifolia (2 n = 4 x = 60), Chrysolaena flexuosa (2 n = 2 x = 20), and Cyrtocymura cincta (2 n = 4 x = 40). The relevance of the results is discussed in relation to the available data for each of the analysed taxa.

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Nuevas combinaciones en los géneros sudamericanosque Lessingianthus presenta 120 especies con una gran concentración en el sudeste de Brasil. Se estima que gran cantidad de especies todavía incluidas en Vernonia no han sido estudiadas apropiadamente y en consecuencia su posición y estatus taxonómicos permanecen inciertos. En este trabajo se analizó la morfología de los granos de polen y de algunos microcaracteres florales para aportar datos que permitieron transferir seis taxones de Vernonia al género Lessingianthus y otras dos especies del mismo género a Lepidaploa. PALABRAS CLAVE:Vernonia, Lepidaploinae, Vernoniinae, sistemática. ABSTRACTThe genera Lepidaploa (Cass.) Cass. and Lessingianthus H. Rob. (Vernonieae, Asteraceae) were established to separate taxa initially placed in Vernonia Schreb. sect. Lepidaploa (Cass.) DC. subsect. Axilliflorae Benth. & Hook. and Vernonia sect. Lepidaploa subsect. Macrocephalae Benth. & Hook., respectively. As presently delimited, Lepidaploa is comprised of about 150 species widely distributed in South America, while Lessingianthus presents 120 species having a concentration in southeastern Brazil. It is estimated that a large amount of several species still included in Vernonia have not been examined and consequently their taxonomic position remains uncertain. We analyzed pollen morphology and floral microcharacters of several Vernonia species, which allowed the transfer of six taxa previously placed in this genus to Lessingianthus and other two species of the Vernonia to Lepidaploa.

SUMMARYThe genus Stenocephalum (Vernonieae, Asteraceae) includes six South American species that have cylindrical heads, 4-11 florets by capitula, cymose inflorescences and type 'C' pollen. Until now, Stenocephalum monticola has been considered as a synonym of S. apiculatum. However, the analysis of the type material and additional specimens indicate that it is a quite different species, which differs in leaf size, pubescence and capitula arrangement. Stenocephalum monticola has leaves of 9 -20 mm long, leaf blades villous at the base and capitula agglomerate at the stems tips, while S. apiculatum presents leaves of 30-60 mm long, leaf blades basally glabrous and heads mostly solitary, arranged in a pseudo-spiciform inflorescence. Consequently, in this paper S. monticola is resurrected from the synonymy of S. apiculatum, re-described and illustrated.