We investigated seed dormancy among species of Melastomataceae from Neotropical montane vegetation of Brazil. Four out of 50 studied species had dormant seeds:Miconia corallina(Miconieae), Tibouchina cardinalis(Melastomeae), Comolia sertularia(Melastomeae) andChaetostoma armatum(Microlicieae). For these four species, germinability of seeds collected in different years was always < 10% and the percentages of embryoless seeds and non-viable embryos were both insufficient to explain low or null germinability. This is the first unequivocal report of seed dormancy in tropical Melastomataceae. The production of seeds with permeable seed coats and fully developed, differentiated embryos indicates the occurrence of physiological dormancy. The reconstructed phylogenetic tree of the 50 species suggests that physiological dormancy evolved multiple times during the evolutionary history of Melastomataceae in this vegetation. Physiological dormancy evolved in species and populations associated with xeric microhabitats, where seeds are dispersed in unfavourable conditions for establishment. Therefore, drought-induced mortality may have been a strong selective pressure favouring the evolution of physiological dormancy in Melastomataceae. We argue that dormancy may have been independently selected in other lineages of Cerrado plants colonizing xeric microhabitats and dispersing seeds at the end of the rainy season. The contributions of our data to the understanding of seed dormancy in tropical montane vegetation are discussed.

-(Comparative morphology of seedlings and saplings of species of the native leguminous trees: species of Phaseoleae, Sophoreae, Swartzieae and Tephrosieae). In this paper, seedlings and saplings of Erythrina speciosa (Phaseoleae), Holocalyx balansae and Sophora tomentosa (Sophoreae), Swartzia langsdorffii (Swartzieae), Lonchocarpus muehlbergianus and Platycyamus regnellii (Tephrosieae) were studied, aiming to describe the morphology at early developmental stages of leguminous trees, in order to identify species, and provide information for taxonomic, phylogenetic and ecological works. Erythrina speciosa showed epigeal-fleshy seedlings with two eophylls only. The species of Sophoreae and Swartzieae formed hypogeal seedlings with 5-7 eophylls in Holocalyx balansae, 6-15 in Sophora tomentosa and 7-10 in Swartzia langsdorffii. In Tephrosieae, Lonchocarpus muehlbergianus showed hypogeal seedlings with 8-10 eophylls, while Platycyamus regnellii had epigeal-fleshy seedlings with two eophylls only. Seedlings and saplings of Erythrina speciosa and Platycyamus regnellii are similar and are distinguished only by the presence of spines and extra-floral nectaries in the former. The phyllotaxy of Sophoreae and Swartzieae show alternate nodes, while in Phaseoleae and Tephrosieae the first node is opposite, becoming alternate in the subsequent ones. Radicular nodules were observed in all species but Holocalyx balansae and Platycyamus regnellii.RESUMO -(Morfologia comparada de plântulas e plantas jovens de leguminosas arbóreas nativas: espécies de Phaseoleae, Sophoreae, Swartzieae e Tephrosieae). Dados morfológicos referentes às fases juvenis das plantas são tão importantes quanto escassos na literatura. Neste trabalho, foram estudadas as plântulas e plantas jovens de Erythrina speciosa (Phaseoleae), Holocalyx balansae e Sophora tomentosa (Sophoreae), Swartzia langsdorffii (Swartzieae), Lonchocarpus muehlbergianus e Platycyamus regnellii (Tephrosieae), como parte de um amplo projeto com leguminosas arbóreas, que objetivou descrever a morfologia das fases juvenis, com vistas à identificação das espécies, fornecendo subsídios para trabalhos taxonômicos, filogenéticos e ecológicos. Erythrina speciosa apresentou plântula epígeo-carnosa, formando somente dois eofilos. As espécies de Sophoreae e Swartzieae formaram plântulas hipógeas, sendo constituídos de cinco a sete eofilos em Holocalyx balansae, de seis a 15 em Sophora tomentosa e de sete a 10 em Swartzia langsdorffii. Em Tephrosieae, Lonchocarpus muehlbergianus produziu plântula hipógea e constituiu de oito a 10 eofilos e Platycyamus regnellii formou plântulas epígeo-carnosas e apenas dois eofilos. As plântulas e plantas jovens de Erythrina speciosa e de Platycyamus regnellii são similares, sendo distinguidas somente pela presença de espinhos e nectários extra-florais na primeira. Com relação à filotaxia, as espécies de Sophoreae e Swartzieae apresentaram somente nós alternos, enquanto que, em Phaseoleae e Tephrosieae, a filotaxia do primeiro nó eofilar foi oposta, passa...

Acrocomia aculeata is an oil producing tropical palm tree with exceptional potential for producing biofuel.As the propagation of this species is often difficult because of its pronounced seed dormancy, the present work examined the morphology and the anatomy of zygotic embryos and seedlings during in vitro germination. Embryos were put in MS media supplemented with organic compounds and cultivated in the dark at 30°C for 20 days. The dry weights, lengths, and diameters of the cotyledonary petioles, haustoria, roots, ligules, and leaf sheaths of embryos obtained from mature seeds and seedlings removed from culture were measured every 2 days; anatomical and histochemical evaluations were performed on embryos and seedlings removed from culture after 2, 5, 8, 10, 12, and 15 days. Elongation of the embryo axis was observed to initiate after 2 days. Elongation of the cotyledonary petiole was observed starting on the fifth day; this is a morphological indication of germination that is associated with the formation of starch and raphides as well as the differentiation of tracheary elements. The growth of the cotyledon is due to increases in cell volumes as well as the development of a meristematic band peripheral to the haustorium. In spite of the fact that the radicle is less differentiated than the plumule, radicular development is precocious and the root emerges first, indicating the absence of morphological dormancy. Atrophy of the haustorium and the accumulation of phenolic compounds in subepidermal cell layers occur due to culturing conditions.

-(Cypsela or achene? Refining terminology by considering anatomical and historical factors). The worry about the indiscriminate use of the terms cypsela and achene for the fruits of Asteraceae has been frequently detached by specialists in this family. The present work was developed aiming to verify the existence of arguments to justify the adoption of a term against the other. After historical and anatomical analysis, we concluded that there is technical basis to consider cypsela and achene as different types of fruits. For Asteraceae, the correct is to call cypsela; achenes are only derived from superior ovaries, as in Plumbaginaceae.

-(Comparative developmental morphology and anatomy of fruits of Vernonia brevifolia Less. and V. herbacea (Vell.) Rusby (Asteraceae)). In this work, the morphology, anatomy and ontogeny of the pericarp and pappus of Vernonia herbacea and V. brevifolia were described. Both species are very similar, possessing inferior, bicarpellate, syncarpous and unilocular ovary. In the pericarp formation, none region is multiplicative. The exocarp is uniseriate and recovered by thin cuticle. Long, multicellular and bisseriate non-glandular trichomes were observed, which persisted until maturity; capitate glandular trichomes are caducous. The outer mesocarp is composed of two or three fiber layers in V. herbacea, and only one in V. brevifolia, in both it accumulates prismatic crystals. In both species, the inner mesocarp is parenchymatous. Collateral vascular bundles occur immersed between outer and inner mesocarp. The endocarp is uniseriate, presenting two or three layers in the carpel fusing regions only. In the pericarp apical portion, there is a protuberance at the double pappus insertion, composed by lignified cells, some of them projected peripherally. At the fruit base, there is a carpopodium; in V. herbacea it is bigger and has druses and styloids; in V. brevifolia it is reduced and there is no crystals. At maturity, the pericarp of both species is dehydrated in such way that the cell layers are collapsed, and it is possible to distinguish only some exocarp cells and non-glandular trichomes, the outer mesocarpic fibers and crystals, and the xylem of vascular bundles.Key words -anatomy, ontogeny, pappus, pericarp RESUMO -(Morfoanatomia comparada dos frutos em desenvolvimento de Vernonia brevifolia Less. e V. herbacea (Vell.) Rusby (Asteraceae)). Neste trabalho, o pericarpo e pápus de Vernonia brevifolia e V. herbacea são descritos morfoanatômica e ontogeneticamente. As espécies são muito similares entre si, possuindo ovário ínfero, bicarpelar, sincárpico e unilocular. Na formação do pericarpo, nenhuma das regiões é multiplicativa. O exocarpo é unisseriado e recoberto por fina cutícula. Observamse tricomas tectores longos, multicelulares e bisseriados, que persistem até a maturidade; os tricomas glandulares capitados não se mantêm na maturidade. O mesocarpo externo é composto por duas ou três camadas de fibras em V. herbacea e apenas uma em V. brevifolia, acumulando cristais prismáticos. O mesocarpo interno é similar nas espécies, de natureza parenquimática. Feixes vasculares colaterais ocorrem imersos entre o mesocarpo externo e o interno. O endocarpo é unisseriado, havendo duas a três camadas apenas nas regiões de fusão dos carpelos. Na porção apical do pericarpo, observa-se uma protuberância onde se insere o pápus duplo, composto por células lignificadas, algumas projetadas perifericamente. Na base do fruto, ocorre o carpopódio que, em V. herbacea, é mais amplo e abriga drusas e estilóides; em V. brevifolia, o carpopódio é reduzido e não ocorrem cristais. Na maturidade, o pericarpo de ambas as espécies é desid...

It is often necessary to process large plant samples for light microscopy studies, but due to structural characteristics of plant tissues, especially intercellular spaces, large vacuoles, and phenolic substances, results are often unsatisfactory. When large samples are embedded in glycol methacrylate (GMA), their core may not polymerize, remaining soft and moist and making it difficult to cut microtome sections. This situation has been erroneously interpreted as the result of poor infiltration, when the soft core of these samples is actually the result of incomplete polymerization. While GMA is in fact present inside samples, unsatisfactory polymerization results from rapid external polymerization that does not allow sufficient hardener to reach the sample core, while the relatively large volume of GMA inside the tissue block also dilutes the hardener. In this chapter we propose a new method for processing large plant specimens that avoids these problems by: (1) slowing the polymerization process through cooling in order to permit the penetration of hardener into the sample core and (2) increasing the hardener:GMA ratio to aid polymerization of the sample core.

The mobilization of palm seed reserves is a complex process because of the abundance and diversity of stored compounds and results from the development of a highly specialized haustorium. This work focused on the important Neotropical oleaginous palm Acrocomia aculeata, with the aim of defining phases of seedling development associated with mobilization of reserves and elucidating the role of haustorium and endosperm in this process. Standard methods were performed, including biometric, anatomical, and histochemical analyses, as well as the evaluation of the activities of the enzymes endo-β-mannanase and lipase, throughout the reserve mobilization in seeds during germination and in seedlings. Seeds of A. aculeata stored large quantities of proteins, lipids, and polysaccharides in the embryo and endosperm. The mobilization of reserves initiated in the haustorium during germination and subsequently occurred in the endosperm adjacent to the haustorium, forming a gradually increasing zone of digestion. Proteins and polysaccharides were the first to be mobilized, followed by lipids and cell wall constituents. The haustorium activates and controls the mobilization, forming transitory reserves and translocating them to the vegetative axis, while the endosperm, which also has an active role, serves as a site of intense enzymatic activity associated with protein bodies. Seedling development can be described as occurring in six phases over a long period (approximately 150 days) due to the large amount of seed reserves. This process exhibits an alternation between stages of accumulation and translocation of protein, lipid, and carbohydrate reserves in the haustorium, which favors the seedling establishment and the reproductive success of the species.

IntroduçãoO Cerrado é um bioma que se restringe ao Brasil, com somente pequenas áreas na Bolívia e no Paraguai (Ratter 2004). É reconhecido como a savana mais rica do mundo em biodiversidade e contém um gradiente natural de fi sionomias vegetais de acordo com as condições do solo e disponibilidade de água (Pivello & Coutinho 1996). No Cerrado, há grande riqueza de espécies de Asteraceae, muitas delas endêmicas (Almeida et al. 2005). Com 106 gêneros e 557 espécies listadas por Mendonça et al. (1998), a família destaca-se por sua importância econômica, visto que muitas espécies são comercializadas principalmente para fi ns medicinais, ornamentais e culinários, além de várias delas serem invasoras. Isso torna os estudos morfoanatômicos dos frutos e sementes de plantas desta família indispensáveis para a compreensão de suas estratégias reprodutivas e para gerar subsídios para pesquisas futuras, de modo a explorar seus possíveis benefícios ou mesmo para controlar as ruderais.As Asteraceae apresentam órgãos reprodutivos morfologicamente homogêneos, com ovário ínfero, sincárpico e bicarpelar, com um único óvulo unitegumentado e basal; os frutos são denominados cipselas ou aquênios, dependendo do autor considerado, muitas vezes com pápus bem desenvolvido e carpopódio distinto, onde se dá a abscisão do fruto no momento da dispersão (Corner 1976;Bremer 1994;Judd et al. 1999). Neste trabalho, adota-se o termo cipsela, conforme recentemente indicado por Marzinek et al. (2008), que consideraram que a origem complexa do pericarpo, produzido pelo desenvolvimento do receptáculo e da parede ovariana do ovário ínfero, é motivo sufi ciente para separar as cipselas dos aquênios, os quais são frutos simples, com pericarpo originado apenas pela parede ovariana desenvolvida.Corner (1976) generalizou que as sementes de Asteraceae são pequenas, com tegumento fi no e papiráceo, geralmente albuminosas, embora Judd et al. (1999) destaquem que o endosperma é escasso. Segundo as descrições de Corner (1976), as sementes de Asteraceae são constantes em suas características estruturais, mas o endosperma é variável, podendo ser celular ou nuclear, oleaginoso, persistente ou não.A literatura relata variações na vascularização seminal para a família e Corner (1976) destacou três possibilidades. Na primeira, um único feixe vascular estende-se ao redor da semente, partindo do funículo até a região micropilar; na segunda, a vascularização é composta por dois a três feixes pós-calazais, estendendo-se até a micrópila; e na terceira, o feixe rafeal divide-se na entrada do funículo, produzindo platensis foi selecionada para a realização deste trabalho, que objetiva descrever a morfoanatomia e o desenvolvimento do pericarpo e da semente desta espécie, comparando os resultados com a literatura. O material coletado foi processado segundo técnicas usuais. O ovário é ínfero, bicarpelar, sincárpico, unilocular, com um óvulo anátropo, unitegumentado, tenuinucelado, formado em placentação basal. A parede ovariana é homogênea, com células mais densas perifericame...