Development, structure and distribution of colleters in Mandevilla illustris and M. velutina (Apocynaceae)

Colleters of Mandevilla illustris and M. velutina are present on the cotyledons, shoot apices, mature leaves and on the nodal region, where they are interpetiolar and intrapetiolar. In M. velutina there are two colleters on the adaxial basal part of the leaf blade, and in M. illustris, this number varies. The differentiation of the colleters occurs in the early stages of leaf development. When colleters are mature, they consist of a long head on a short stalk. The central core of the colleter is made up of parenchymatous cells that may exhibit phenolic compounds and is surrounded by radially elongated epithelial cells. The foliar and intrapetiolar colleters can exhibit vascularization. The colleters produce a translucient sticky substance that reacts positively to polysaccharides and, before senescence, they produce lipophilic substances. The Mandevilla colleters data can give support to the taxonomy and phylogeny of the Apocynaceae.

Leaf and calycine colleters in Odontadenia lutea (Apocynaceae - Apocynoideae - Odontadenieae): their structure and histochemistry

The structure and histochemistry of colleters found on the vegetative and floral apices of Odontadenia lutea are described. Colleters occur on vegetative apices starting at the fourth node, with 68 to 80 colleters being found at each node. Each leaf primordium has only one colleter of axillary origin, 3-5 intra-petiolar, and 12-16 inter-petiolar (intra-stipular). There are four types of colleters: standard, bipartite standard, sessile, and bipartite sessile. Colleters on the reproductive apices alternate with the sepals and are sessile, reduced sessile, tripartite laminar sessile, or asymmetrical. All of the colleters have a central nucleus of parenchymatous cells covered by a palisade uniseriate secretory epidermis and a thin cuticle. Secretory idioblasts were observed in the parenchymatous axis. Vascularization was observed only in standard axillary and laminar colleters. Crystals were observed in the parenchyma of the axillary colleter. Histochemical tests demonstrated that there was no rupturing or distension of the cuticle during the secretion process. Mucilage was identified using the PAS reaction as well as by Mayer's reagent and Ruthenium red staining. The calycine colleters had two distinct secretory phases, the first synthesizing mucilage and the second producing phenolic compounds.

Ontogenesis, structure and ultrastructure of Hymenaea stigonocarpa (Fabaceae : Caesalpinioideae) colleters

The genus Hymenaea is characterized by a great diversity of secretory structures, but there are no reports of colleters yet. The objectives of this study are to report the occurrence and describe the origin and structure of colleters in Hymenaea stigonocarpa Mart. ex Hayne. Shoot apex samples were collected, fixed, and processed for light microscopy, scanning electron microscopy, and transmission electron microscopy as per usual methods. Colleters occur predominantly on the stipule's adaxial side. These structures are found at the base on a narrow strip, corresponding to the median vein up to half the length of the stipule. When present on the abaxial side, they are concentrated at the base and restricted to the margins. Colleters develop from the protoderm; they are elongate and club-shaped. Their body has no stratification; their surface cells differ from the inner cells only in position and presence of cuticle. Colleter cells have thin walls, dense cytoplasm, large nuclei, many mitochondria, rough endoplasmic reticulum, and abundant dictyosomes. Histochemical tests with Ruthenium red showed pectic compounds in the cytosol. In H. stigonocarpa, colleter arrangement is compatible with the hypothesis that they protect shoot apex. In this species, protection is reinforced by the sheath formed by the stipule pairs.

Colleters in Caryocar brasiliense (Caryocaraceae) ontogenesis, ultrastructure and secretion

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development and evolution of the gynoecium in Myrteae (Myrtaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Wave-generated flow on coral reefs - an analysis for two-dimensional horizontal reef-tops with steep faces

Waves breaking on the seaward rim of a coral reef generate a flow of water from the exposed side of the reef to the sheltered side and/or to either channels through the reef-rim or lower sections of the latter. This wave-generated flow is driven by the water surface gradient resulting from the wave set-up created by the breaking waves. This paper reviews previous approaches to modelling wave-generated flows across coral reefs and discusses the influence of reef morphology and roughness upon these flows. Laboratory measurements upon a two-dimensional horizontal reef platform with a steep reef face provide the basis for extending a previous theoretical analysis for wave set-up on a reef in the absence of a flow [Gourlay, M.R., 1996b. Wave set-up on coral reefs. 2. Set-up on reefs with various profiles. Coastal Engineering 28, 1755] to include the interaction between a unidirectional flow and the wave set-up. The laboratory model results are then used to demonstrate that there are two basic reef-top flow regimes-reef-top control and reef-rim control. Using open channel flow theory, analytical relationships are derived for the reef-top current velocity in terms of the offreef wave conditions, the reef-top water depth and the physical characteristics of the reef-top topography. The wave set-up and wave-generated flow relationships are found to predict experimental values with reasonable accuracy in most cases. The analytical relationships are used to investigate wave-generated flows into a boat harbour channel on Heron Reef in the southern Great Barrier Reef. (c) 2005 Elsevier B.V. All rights reserved.