Chromosome numbers were determined in 29 accessions of wild and semidomesticated Capsicum species from the EMBRAPA Hortaliças (Brazil) germplasm collection. 2 n = 24 was found in C. baccatum var. praetermissum , C. chinense , C. flexuosum and C. parvifolium , while C. buforum , C. campylopodium , C. cornutum , C. schottianum , C. villosum var. villosum and five other native south-eastern Brazilian species not yet taxonomically named all had 2 n = 26 chromosomes. These are the first chromosome number determinations for C. cornutum , C. schottianum , C. villosum var. villosum and the five other Brazilian taxa. Our data confirm published data for C. baccatum var. praetermissum , C. campylopodium , C. chinense , C. flexuosum and C. parvifolium , but not for C. buforum . The prevalence of 2 n = 26 chromosomes among Brazilian species, along with the morphological and ecological characteristics presented by the wild and semidomesticated species occurring in Brazil, form a pattern different from that found in Andean wild and semidomesticated species. This supports the hypothesis that there are two different evolutionary lines in the genus and that the native south-eastern Brazilian species belong to the ancestral Capsicum gene pool.

Chromosome numbers were determined for 125 accessions of 92 taxa of Mimosa from all five of Barneby's (Mem New York Bot Gard 65:1-835, 1991) taxonomic sections. For 69 species, 1 subspecies and 8 varieties, chromosome numbers are presented for the first time, for 6 species and 1 variety previously published data have been confirmed and for 3 species and 2 varieties different numbers were found. Results show that 74% of the accessions were diploid (2n = 2x = 26) and 26% polyploid, these mostly tetraploid (2n = 4x = 52) but with two triploid (2n = 3x = 39). These results double the number of Mimosa species for which the chromosome count is known from less than 10% previously reported to more than 20%, representing an important advance in the cytotaxonomy of this legume genus. These results together with literature data show that ca. 78% of Mimosa species are diploid. Polyploids are present in most of the taxonomic sections and in different lineages across the genus.No particular chromosome number is restricted to a given section or lineage. A possible relation between geography, species distribution, polyploidy and invasiveness was detected, however, further studies based on more accessions, especially from higher latitudes, are required before firm conclusions can be drawn.

Several species of the genus Paspalum L. are important forages, due to quality, productivity and tolerance to environmental stresses. Chromosome numbers, meiotic configurations and pollen fertility were evaluated in a collection of 85 accessions of Paspalum notatum Flügge and in seven accessions of Pensacola (P. notatum var saurae). All P. notatum accessions were tetraploid, with 2n = 4x = 40, except one diploid accession, considered as an escape of Pensacola. All Pensacola plants had 2n = 2x = 20. Meiotic configurations at diakinesis and metaphase I varied among tetraploid accessions, from plants with only bivalents to plants with high frequency of quadrivalents. Pollen fertility varied from 82.5 to 95.9% among diploid accessions and from 72.4 to 97.9% among the tetraploid. Due to the apomictic mode of reproduction of tetraploid P. notatum, meiotic irregularities can be maintained by the plants without harming their propagation. At the same time, pollen fertility should be high enough to assure endosperm development, since the species is pseudogamous. Wild diploid P. notatum populations, apart from the endemic P. notatum var saurae are very rare. From a plant breeding point of view, all the examined tetraploid accessions are potentially male-fertile and could be used as males in crosses. Key words: apomixis, chromosome numbers, meiotic configurations, plant breeding, pollen fertility DADOS CITOGENÉTICOS PARA ACESSOS DEPaspalum notatum FLÜGGE RESUMO: Muitas espécies do genus Paspalum L. são importantes forragens, devido à qualidade, produtividade e tolerância para o stress ambiental. Números cromossômicos, configurações meióticas e fertilidade do pólen foram analisados em uma coleção de 85 acessos de Paspalum notatum Flügge e sete acessos de Pensacola (P. notatum var saurae). Todos os acessos de P. notatum eram tetraplóides, com 2n = 4x = 40, com exceção de um diplóide, considerado como escape de Pensacola. Todas as plantas de Pensacola examinadas tinham 2n = 2x = 20. Foi verificada variação entre os acessos tetraplóides quanto às configurações cromossômicas em diacinese e metáfase I, desde plantas com apenas bivalentes até aquelas com alta freqüência de quadrivalentes. A fertilidade do pólen variou de 82,5 a 95,9% entre os acessos diplóides e de 72,4 a 97,9% entre os tetraplóides. Devido ao modo de reprodução apomítico de P. notatum tetraplóide, irregularidades meióticas podem ser mantidas sem prejuízo da propagação. Ao mesmo tempo, a fertilidade do pólen deve ser suficientemente alta para assegurar a formação do endosperma, já que a espécie é pseudogâmica. Diplóides silvestres de P. notatum, além do endêmico P. notatum var saurae são muito raros. Do ponto de vista do melhoramento, todos os tetraplóides são potencialmente macho-férteis e poderiam ser utilizados como genitores masculinos em cruzamentos. Palavras-chave: apomixia, números cromossômicos, configurações meióticas, melhoramento genético, fertilidade do pólen

Original chromosome determinations are presented for 20 American Lupinus taxa, including, for the first time, unifoliolate species, together with first data on meiotic behaviour and pollen fertility for some South American species. Most of the Brazilian multifoliolate L. lanatus , L. rubriflorus , L. multiflorus , L. paranensis , L. bracteolaris and L. reitzii and unifoliolate L. crotalarioides , L. guaraniticus and L. velutinus accessions analysed presented regular chromosome pairing. Meiotic indexes and estimations of pollen viability were higher than 90% for all species and accessions analysed, reflecting the generally regular meiotic behaviour of these plants. Chromosome numbers were determined for the first time for the eastern South-American species L. guaraniticus , L. crotalarioides , L. paranensis , L. paraguariensis and L. velutinus ( n = 18 or 2 n = 36) and for the Andean L. ballianus , L. eanophyllus , L. huaronensis , L. semperflorens , plus another eight taxa (2 n = 48) from Peru and Bolivia, and L. bandelierae (2 n = 36) from Bolivia. Chromosome numbers were confirmed for L. lanatus , L. rubriflorus (2 n = 36), L. bracteolaris (2 n = 34) and L. microphyllus (2 n = 48). In the three accessions of the North American unifoliolate species, L. cumulicola and L. villosus , a chromosome number (2 n = 52) previously unknown among American taxa was found. The results of the study, plus published data, support the suggestions that south-eastern South American species are a group cytologically differentiated from the Andean as well as from most other American ones, and that the Brazilian and the North American unifoliolate Lupinus had independent origins.

The Paspalum genus includes several species that are important for livestock in Rio Grande do Sul, such as P. notatum and P. guenoarum, typical of native pastures of the Pampa biome. The aim of this study was to investigate forage production and chemical composition of four ecotypes of these species in relation to the cv. 'Pensacola' (P. notatum). Ecotypes of P. guenoarum (Azulão and Baio) and P. notatum (André da Rocha and Bagual) and the cv. 'Pensacola' were evaluated for two years, during which four cuts/year were made. The work was carried out under field conditions at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (30°05'S; 51°39'W), in a completely randomized design. P. guenoarum stood out for higher productivity and greater tolerance to cold; the Azulão ecotype showed more autumn production in relation to the other ecotypes. Crude protein content ranged from 14 (Baio) to 15% ('Pensacola'); for neutral detergent fiber, the variation was 68 (Azulão) to 71% ('Pensacola') and for acid detergent fiber there was a variation of 38 ('Pensacola') to 43% (Baio). The data demonstrates the potential of native genotypes for use as cattle feeding in southern Brazil.

Summary Meiotic behavior was analysed in 30 accessions of 12 wild (Capsicum flexuosum, C. parvifolium, C. buforum, C. campylopodium, C. cornutum, C. pereirae, C. friburgense, C. schottianum, C. villosum var. villosum, and 3 new species) and 2 semi-domesticated (C. baccatum L. var praetermissum and C. chinense) Brazilian Capsicum species. This is the first report on meiosis for most of these taxa. Except for C. baccatum L. var praetermissum, C. chinense, C. flexuosum and C. parvifolium, with 2nϭ24 chromosomes, all other taxa had 2nϭ26 chromosomes, a number previously considered as not common in the genus. Meiotic pairing was generally regular (12 or 13 bivalents) for most of the species analyzed. However, different irregularities such as univalents, multivalents, bridges, chromosome stickiness, unoriented chromosomes, monads, dyads and polyads, among others, were found at both meiosis I and meiosis II, leading to unbalanced final meiotic products but generally not a high pollen sterility. It was not possible to establish with certainty if these irregularities were due to genetic (meiotic mutations) or environmental (such as pests and diseases) causes.

-(Chromosome numbers and systematic implications in species of subfamily Caesalpinioideae (Leguminosae) from the Southern region of Brazil). The subfamily Ceasalpinioideae (Leguminosae) comprises around 2,800 species, many of which occurring in Brazil. For the Southern region of Brazil, 56 species economically, socially and scientifically important, are cited, distributed along different environments, but detailed taxonomic and cytogenetic studies are still missing. This paper reports chromosome number analysis in 74 accessions of 27 taxa belonging to ten genera of tribes Cassieae, Caesalpinieae, and Cercideae. The determined chromosome numbers were 2n = 32, 28, 26, 24, 22, 16 and 14. For seven species the chromosome numbers were determined for the first time: Cassia leptophylla, Senna araucarietorum, S. hilariana, S. neglecta, S. oblongifolia, Chamaecrista repens and Pomaria stipularis. Most species had 2n = 28 chromosomes, 2n = 26, 24, and 22 being also found. The genus Chamaecrista differs from the others studied as all its taxa presented 2n = 32, 16, and 14, the first one derived by polyploidy. The basic number of x = 14 was proposed for the species of nine of the studied genera, while x = 13, 12 and 11 would have probably been originated by disploidy. For the genus Chamaecrista, x = 8 is suggested for most species and x = 7 for the species of section Xerocalyx. Polyploidy seems to have played an important role in the initial diversification of the group, accompanied by several disploid reductions during the evolutionary process. The number of chromosomes distinguishes Chamaecrista from the other genera. This, together with other analyzed characteristics, as well as literature data, supports the separation of this genus from the other Cassieae genera.

Trifolium argentinense Speg. is an amphicarpic species that occurs naturally in native pastures of Rio Grande do Sul, southern Brazil. Amphicarpy is a rare mode of reproduction in which aerial and subterranean seeds are produced by the same individual. In the present paper, we compare morphology, anther number, pollen viability, seed production and mode of reproduction of T. argentinense flowers, and comment on the life strategy of the species. Plants grown from aerial seeds and from the regrowth of storage roots of aerial plants had longer stolons and a larger plant diameter than did those grown from subterranean plants. Plants grown from seeds were also taller than plants grown from storage roots. More resources were allocated to subterranean reproduction in plants of subterranean origin than in those of aerial origin. Aerial flowers produced more seeds, presented more anthers and produced more pollen grains than did the subterranean ones. T. argentinense is a versatile species, self- and cross-pollinated, consistent with the values of high polymorphism information content. T. argentinense adopts the ‘pessimistic strategy’ (early allocation of energy to large subterranean propagules), common in amphicarpic species when growing in disturbed habitats, such as the native pastures of Rio Grande do Sul, where intense grazing and trampling, as well as long seasonal dry spells, may periodically destroy the aerial plants, thus assuring survival by germination of subterranean seeds and regrowth of storage roots.