ABSTRACT Hydropotes are specialized epidermal structures involved in water and mineral flux into and out of the plant body. We analyzed hydropote morphology of four species of Nymphaeaceae: Nymphaea caerulea, Nymphaea lotus, Nymphaea rubra, and Victoria amazonica. Leaf samples were processed following conventional techniques for plant anatomy and for scanning and transmission electron microscopy. We observed hydropotes comprising an elongated apical sharp-pointed portion with a base composed of two to three short specialized cells. In a later developmental stage the apical sharp-pointed portion was detached and the mature hydropotes comprised an upper lens-shaped cell, a bowl-shaped cell and a large foot cell. Ultrastructural analysis revealed that the lens-shaped cell possesses labyrinthine projections in its outer periclinal wall and abundant plasmodesmata in its inner periclinal wall. Several mitochondria were present in the cytoplasm of both the lens-shaped and the bowl-shaped cells. The cytoplasm of the foot cell was reduced and possessed plastids with starch grains. The ultrastructure of the hydropotes is typical of cells involved in transporting substances and corroborates their role in the flux of substances into and out of the cell. These findings contribute to a better understanding of the functioning of hydropotes and shed light on this little-explored issue.

ABSTRACT Dipteryx, Pterodon and Taralea are legume genera known for secreting oils, produced in secretory canals and cavities, with medicinal properties. We analyzed the distribution, morphology and histochemistry of these glands in leaves and stems of Dipteryx alata, Pterodon pubescens and Taralea oppositifolia, three Neotropical species, using standard techniques for anatomy and histochemistry. Secretory spaces, i.e. secretory cavities and canals, exhibited a wide lumen and a single layer of epithelium. Digitiform epithelial cells, forming trabeculae protruding into the lumen, were seen in all three species. Secretory cavities with a rounded or oval lumen and secretory canals with an elongated lumen in longitudinal sections were found only in T. oppositifolia. In D. alata and P. pubescens, only secretory cavities were found. In P. pubescens, secretory cavities occurred in the leaf blade margin. In T. oppositifolia, secretory spaces were much more numerous than in the other two species. Terpenes, total lipids, phenolic compounds, alkaloids and polysaccharides were detected in the secretory spaces of the three species. The abundance of secretory spaces, the presence of canals in T. oppositifolia and the position of cavities in P. pubescens are features with potential diagnostic value for their respective genera.

ABSTRACT Lamiaceae contains many species known for their aromatic properties that are produced by the production of essential oils in glandular trichomes. Hyptis is one of the most common genera of Lamiaceae in the Brazilian flora, and includes several species with medicinal value. However, studies on the morphology and functioning of their glandular trichomes are lacking. We analyzed the morphology, histochemistry and ultrastructure of the glandular trichomes in leaves of H. villosa, emphasizing the differential distribution of actin filaments and microtubules in cells secreting hydrophilic and lipophilic compounds. Four morphotypes of glandular trichomes were identified. Total lipid, terpenes, alkaloids, phenolic compounds, proteins and polysaccharides were histochemically detected in all morphotyes. This evidences the mixed nature of the secretions of this species, although there are differences in the prevalence of lipophilic and hydrophilic components among the glandular morphotypes and among the cells of the same trichome. The actin microfilaments are more abundant in cells that secrete mainly hydrophilic compounds, and microtubules predominate in cells that secrete lipophilic compounds. Our results corroborate the correlation between the glandular morphotype and the composition of the secretion produced, with a differential distribution of the cytoskeletal elements according to the prevalence of either hydrophilic or lipophilic substances.

Os pulvinos, estruturas responsáveis por movimentos foliares, rápidos ou lentos, em resposta a estímulos externos ou endógenos, constituem uma característica marcante das leguminosas. Os ajustes no posicionamento foliar representam um mecanismo eficiente que permite a maximização da fotossíntese em condições adversas. Na literatura disponível, a maioria das informações sobre a estrutura de pulvinos refere-se a poucas espécies de leguminosas, especialmente aquelas que apresentam movimentos rápidos. Neste trabalho é descrita a anatomia do pulvino primário de nove espécies de leguminosas nativas do cerrado com diferentes tipos e velocidades de movimento foliar, buscando identificar padrões e apontar peculiaridades estruturais. O pulvino primário das espécies estudadas apresenta epiderme unisseriada recoberta por cutícula espessa, córtex parenquimático amplo, sistema vascular central e medula reduzida ou ausente. As células do córtex externo são maiores e apresentam conteúdo fenólico, exceto em Zornia diphylla Pers.; no córtex interno, as células são justapostas e não possuem conteúdo fenólico. Os feixes vasculares colaterais são circundados por uma bainha de fibras septadas. O padrão geral de organização anatômica é comum ao pulvino das espécies estudadas, independentemente da subfamília a qual pertencem. As peculiaridades observadas estão possivelmente relacionadas com o tipo e velocidade do movimento foliar.

The pulvinus, structure responsible for slow or fast leaf movements answering to outside or endogenous stimulus, constitutes a remarkable feature of leguminous species. The leaf position adjustments represent an efficient mechanism that allows the photosynthesis maximization under adverse conditions. In the available literature, the majority of the information about pulvinus structure refers to few leguminous species, especially those with fast movements. In this work the primary pulvinus anatomy of nine leguminous species from Brazilian "cerrado" with different kinds and velocity of leaf movement is described, attempting to identify patterns and to point structural peculiarities. The primary pulvinus of the studied species show uniseriate epidermis recovered by thick cuticle, large parenchymatous cortex, central vascular system and reduced or absent pith. The outer cortex cells are wider and show phenolic compounds, except in Zornia diphylla Pers.; in the inner cortex, the cells are juxtaposed and do not have phenolic content. The collateral vascular bundles are surrounding by a septate fibers sheath. The general anatomy organization pattern is common to the pulvini of the studied species, independently of the subfamily they belong. The observed peculiarities are possible related to the kind and velocity of leaf movement.

Em Pterodon pubescens, os pulvinos primário e secundário, órgãos responsáveis pelos movimentos foliares, apresentam peculiaridades estruturais em relação ao pecíolo e raque. Estas peculiaridades incluem cutícula mais espessa, córtex mais desenvolvido formado por células parenquimáticas de formas variáveis, sistema vascular em posição central, floema circundado por fibras septadas não lignificadas e medula parenquimática reduzida ou ausente. Pecíolo e raque apresentam córtex reduzido constituído por células parenquimáticas isodiamétricas, sistema vascular periférico, floema envolvido por calota de fibras gelatinosas e medula ampla. Compostos fenólicos foram detectados no vacúolo das células corticais dos pulvinos, enquanto que no córtex e medula do pecíolo e da raque foram observados amiloplastos em abundância e ausência de compostos fenólicos. Em geral, as características estruturais do pulvino de P. pubescens são comuns aos pulvinos das demais espécies de Fabaceae e têm sido relacionadas com a intensificação de trocas laterais de íons e água entre células do córtex e sistema vascular, além de proporcionar maior flexibilidade e capacidade de movimento desta região. Já as características do pecíolo e da raque conferem maior rigidez a estas estruturas foliares.

In Pterodon pubescens the primary and secondary pulvini show structural peculiarities in relations of petiole and rachis. These peculiarities include thicker cuticule, more developed cortex with only parenchyma cells with irregular shape, central vascular tissues, presence of septate fibers around the phloem, and absent or reduced pith. Petiole and rachis show reduced cortex constituted by parenchyma isodiameters cells, peripheric vascular tissues surrounded by gelatinous fibers and pith. Phenolic compounds were detected inside vacuole of parenchyma cells of the pulvinus. Starch grains were observed in the parenchyma cells of petiole and rachis. The features of P. pubescens pulvinus are common to pulvini of others species of Fabaceae, and have been associated to the intensification of lateral changes of ion and water between cortical cells and vascular tissues, besides to provide more flexibility and movement capacity of this organ. On the other hand, the features of petiole and rachis give more rigidity to these leaves structures.