Radicular anatomy of twelve representatives of the Catasetinae subtribe (Orchidaceae: Cymbidieae)

Abstract

Considering that the root structure of the Brazilian genera belonging to the Catasetinae subtribe is poorly known, we describe the roots of twelve representatives from this subtribe. For anatomical analysis, the roots were fixed in FAA 50, preserved in ethanol 70% and sectioned at its medium region using razor blades. The sections were stained with 0.05% astra blue and safranin and mounted in glycerin. For the identification of starch we used Lugol´s solution; for lignin, floroglucin chloridric; for lipids, Sudan III, and for flavanoids, potassium hydroxide. The relevant aspects were registered using a digital camera joined with an Olympus microspope (BX51 model). The structural similarities of all roots support the placement of the subtribe Catasetinae into the monophyletic tribe Cymbidieae. Some root features are restricted to one or two taxa and can be useful in the systematics of the subtribe. For example, the occurrence of flavonoidic crystals characterizes the genera Catasetum and Cychnodes, and the number of the velamen layers and the shape of the epivelamen cells are useful to confirm the taxonomic position of Clowesia amazonica. The presence of velamen and flavonoidic crystals was interpreted as an adaptation to the epiphytic habit.

Morpho-anatomical characteristics conferring drought tolerance in roots of sugar cane genotypes (Saccharum L., Poaceae)

“…This is confirmed by the fact that in many monocots, such as terrestrial orchids, the numbers of cortical layers and protoxylem poles are directly correlated with root diameter (Moreira and Isaias 2008). However, each one will influence the overall diameter to variable extents, since they are affected by environment influences that in turn also affect root diameter (Pedroso-de-Moraes et al 2012). This relationship has been shown for plants of the same species grown under variable conditions of water supply, where the shortest distance between the substrate and the stele (fewer cortical layers) can facilitate the absorption of water (Fahn 1982).…”

Anatomia dos órgãos vegetativos de Cattleya violacea (Kunth) Rolfe (Orchidaceae)

“…A composição das paredes celulares do velame nessa família é celulósica, com impregnação em diferentes graus de lignina e suberina, sendo que a lignificação e suberização variam consideravelmente entre as espécies (Noel 1974, Benzing et al 1983), e uma das funções desses espessamentos é prover suporte e evitar o colapso celular durante a dessecação (Noel 1974). Portanto, tais características estão relacionadas ao ambiente estritamente seco e hábito epifítico apresentado pela espécie, uma vez que esse tecido protege o interior da raiz, evitando seu aquecimento e, consequentemente, a perda de água (Pridgeon 1987, Gonzaga & Gonzaga 1996, Pedroso-de-Moraes et al 2012, 2013.…”

“…O número de camadas de parênquima cortical encontrado em C. violacea é muito próximo ao encontrado em Cattleya walkeriana Gardner (Silva & Milaneze-Gutierre 2004), em várias outras espécies do gênero (Stern & Carlsward 2009), e ainda, em algumas espécies amazônicas de Catasetinae (Stern & Judd 2001, Pedroso-de-Moraes et al 2012. As pequenas variações no número de estratos do córtex em orquídeas, geralmente, ocorrem devido às condições ambientais nas quais as espécies se desenvolvem (Alconero 1968, Pedroso-de-Moraes et al 2012, 2013.…”

“…As pequenas variações no número de estratos do córtex em orquídeas, geralmente, ocorrem devido às condições ambientais nas quais as espécies se desenvolvem (Alconero 1968, Pedroso-de-Moraes et al 2012, 2013.…”

Litter-trapping plants: filter-feeders of the plant kingdom

“…). They have been confused with pneumatophores (Holst, ; Pedroso‐de‐Moraes et al ., ), even though these roots lack aerenchyma and are not associated with plants growing in anaerobic habitats. The root basket functions as both the trap and the nutrient absorption zone.…”