Hilda Maria Longhi-Wagner

Reproductive morphology of the early-divergent grass Streptochaeta and its bearing on the homologies of the grass spikelet

Reproductive morphology and development are described in the Brazilian grass Streptochaeta spicata, in order to assess the homologies of the characteristic grass inflorescence, termed a spikelet, and other reproductive organs. Streptochaeta possesses some features that are commonly found in Poaceae, including a well-differentiated embryo. It also possesses some relatively unusual, presumably derived features, such as non-plumose stigmas, which indicate that it could be insect-pollinated. It shares some features with other early-divergent grasses, such as Pharus, which could represent plesiomorphic conditions for grasses. The inflorescence unit in Streptochaeta has been interpreted as a compound branching system or pseudospikelet. The present data suggest that it is a highly modified spikelet, with a modified flower borne either on a different axis to the basal bracts (glumes) or on the same axis as the basal bracts. The three bracts below the stamens are interpreted as homologous to the lodicules. The Streptochaeta spikelet could be considered as morphologically intermediate between the true spikelet of grasses and reproductive units of close grass relatives.

Padrões de distribuição geográfica dos táxons brasileiros de Eragrostis (Poaceae, Chloridoideae)

The genus Eragrostis presents 53 taxa in Brazil, being 38 of them native with distinctive patterns of geographic distribution: exclusively tropical, tropical/subtropical (more abundant in the tropical area but extending their occurrence to the Southern region), tropical and subtropical (as abundant in the tropical region as in the subtropical one), exclusively subtropical, and subtropical/tropical (opposed to the second pattern). An analysis of these patterns is presented together with representative maps.

Phylogenetic analysis of the Briza Complex (Poaceae).

A phylogenetic analysis of the Briza Complex was carried out using three DNA regions (ITS, GBSSI and trnL-trnL-trnF, a total of 2980bp). The searches were performed by three distinct phylogenetic methods, using plastid and nuclear data in separate matrices. All methods produced similar trees per matrix. However there were conflicts when trees resulting from distinct datasets were compared. Phylogenetic relationships were found did not completely fit any circumscription previously proposed for the complex. The early divergence of the Eurasiatic species (B. media, B. maxima and B. minor), and the monophyly of the South American group (including Erianthecium, Rhombolytrum and Gymnachne) support Briza L. sensu stricto, and a single genus for the American group. Briza sensu lato is not supported in most trees, and the American genera cannot be split due to unresolved polytomies. Conflict between chloroplast and nuclear data suggests past reticulation events, although lineage sorting or ITS paralogy cannot be ruled out. Polytomies in the American group may indicate rapid species radiation.

Synopsis of the genus Andropogon L. (Poaceae - Andropogoneae) in Brazil

A revisao do genero Andropogon para o Brasil revelou a ocorrencia de 28 especies, uma das quais introduzida da Africa para cultivo, A gayanus Kunth. Neste trabalho e apresentada uma chave para identificacao das especies, ilustracoes de caracteres diagnosticos e dados sobre a distribuicao geografica das mesmas.

A molecular phylogeny of Raddia and its allies within the tribe Olyreae (Poaceae, Bambusoideae) based on noncoding plastid and nuclear spacers.

The plastid spacer trnD-trnT and the nuclear ribosomal internal transcribed spacer (ITS) were sequenced for 37 samples of herbaceous bamboos (Poaceae: Olyreae), including all Raddia species and allied genera, as well as two members of the woody bamboos (tribes Bambuseae and Arundinarieae), in order to examine their relationships. The sequences were analyzed using maximum parsimony and Bayesian inference. Both the individual and combined analyses of ITS and trnD-trnT supported Olyreae as a monophyletic group. All species of Raddia also formed a well-supported monophyletic group, and combined datasets allowed us to outline some relationships within this group. Individual analyses indicated incongruence regarding the sister group of Raddia, with ITS data weakly indicating Raddiella malmeana whereas trnD-trnT data supported Sucrea maculata in this position. However, the combined analysis supported Sucrea as sister to Raddia, although the monophyly of Sucrea is not well supported. Parodiolyra is paraphyletic to Raddiella in all analyses; Olyra is also paraphyletic, with species of Lithachne, Arberella and Cryptochloa nested within it. Eremitis and Pariana appeared as an isolated clade within Olyreae, and the position of the New Guinean Buergersiochloa remains uncertain within this tribe.

Morphometrics of herbaceous bamboos of the Raddia brasiliensis complex (Poaceae − Bambusoideae): implications for the taxonomy of the genus and new species from Brazil

Morphometric studies were conducted using 25 quantitative characters in 14 populations of the Raddia brasiliensis complex, occurring from Ceará to Rio de Janeiro States, Brazil, in order to identify how many entities exist in this group and how they can be distinguished morphologically. Results of the discriminant and cluster analyses show that we are dealing with five distinct taxa, four of them here described as new species. A group of populations from northern Espírito Santo and southern Bahia showed high differentiation in relation to other areas. They are here considered as the new species R. megaphylla. Two other distinct populations also showed significant differentiation, described as R. lancifolia and R. stolonifera. Raddia brasiliensis s.s. turned out to be polymorphic and closely related to another new species, R. soderstromii. They present some ecological preferences related to soil and water conditions. These conclusions were supported by genetic data based on allozymes analysis.

A contribuição da anatomia foliar para a taxonomia de Raddia Bertol. (Poaceae: Bambusoideae)

Raddia is an herbaceous bamboo genus with nine species in Brazil, one of which extends beyond Brazilian borders. The leaf anatomy of these species was analyzed using optical and scanning electron microscopy, in order to obtain useful characters for the taxonomy of the genus. Other herbaceous bamboos were used for comparison and no characters exclusive to Raddia were found. Leaf anatomy traits had little to do with species delimitation within the genus, sometimes separating only groups of species. Of these traits, the most important were as follows, in transverse section: form of the midrib, position of the intermediate vascular bundle, number of vascular bundles adjacent to the intermediate bundle and form of the fusoid cells. A surface view of the epidermis (SEM) showed differences among the species as regards occurrence, density and distribution of the papillae. Raddia megaphylla R.P. Oliveira & Longhi-Wagner and R. guianensis (Brongn.) Hitchc. & Chase had the largest number of exclusive characters of the species studied. A type of trichome unknown in Bambusoideae was recorded for R. stolonifera R.P. Oliveira & Longhi-Wagner.

Phylogenetic analysis of Saccharum s.l. (Poaceae; Andropogoneae), with emphasis on the circumscription of the South American species

PREMISE OF THE STUDY Polyploidy and reticulate evolution are often a complication for discovering phylogenetic relationships between genera and species. Despite the huge economic importance of sugarcane (Saccharum officinarum-Poaceae, Andropogoneae), the limits of the genus Saccharum and its species are complex and largely unresolved, involving both polyploidy and reticulate evolution. This study aimed to assess the phylogenetic relationships of Saccharum s.l., including Erianthus and Tripidium, as well as investigate the taxonomic circumscription of the South American species of the genus. METHODS Molecular cloning and sequencing of five regions of four low-copy nuclear loci were performed, including Aberrant panicle organization1 (apo1), Dwarf8 (d8), two exons of Erect panicle2 (ep2-ex7 and ep2-ex8), and Retarded palea1 (rep1). Concatenated trees were reconstructed using Maximum Parsimony, Maximum Likelihood, and Bayesian Inference analyses. KEY RESULTS The allopolyploid origin of Saccharum was demonstrated using evidence from nuclear genes. The samples of Saccharum s.l. grouped in two distinct clades, with S. arundinaceum and S. ravennae (= Tripidium, or Erianthus sect. Ripidium) apart from all other species analyzed of the genus. Saccharum angustifolium, S. asperum, and S. villosum correspond to distinct clades (different species). The plants with intermediate morphology between S. angustifolium and S. villosum presented a pattern of paralogues consistent with a hybrid origin. CONCLUSIONS Saccharum s.l. is polyphyletic and Tripidium should be recognized as a distinct genus. However, no strong evidence was found to support the segregation of Erianthus. The taxonomic circumscription of the South American species of the genus was resolved and the occurrence of natural hybrids was documented. Better understanding of the phylogenetic relationships of Saccharum and relatives may be useful for sugarcane breeders to identify potential taxa for interspecific and intergeneric crosses in the genetic improvement of sugarcane.

Olyra bahiensis (Poaceae - Olyreae): uma nova espécie para a mata atlântica do estado da Bahia, Brasil

A new species of Olyra is described and illustrated. Olyra bahiensis R.P.Oliveira & Longhi-Wagner is related to O. ciliatifolia Raddi (widely distributed in South America), and to O. juruana Mez, O. amapana Soderstr. & Zuloaga, and O. loretensis Mez (occurring in the Amazonian Basin), sharing the presence of trichomes covering completely the female floret. The new species occurs in the Atlantic rain forest of Southern Bahia, in the same area where other many species of grasses are found. The populations of O. bahiensis present small number of individuals, growing in shaded areas associated with cocoa plantations. An analytical key for O. bahiensis and allied species is also presented.

Levantamento taxonômico de Cyperus L. 1. subg. Anosporum (Nees) Clarke (Cyperaceae-Cypereae) no Rio Grande do Sul, Brasil

This research included a review of the literature, study of hebarium specimens, collection and observation of populations in the field. Taxonomic decisions were based on external morphology, and resulted in the recognition of fourteen taxa, eleven species and three varieties. Analytical keys for species and varietes, descriptions, illustrations and data on their geographical distribution, habitat and phenology are provided.