Estrutura foliar de Loudetiopsis chrysothrix (Nees) Conert e Tristachya leiostachya Nees (Poaceae)

Abstract

-(Leaf structure of Loudetiopsis chrysothrix (Nees) Conert and Tristachya leiostachya Nees (Poaceae)). Loudetiopsis chrysothrix and Tristachya leiostachya are grasses species showing great morphological similarity, but differing in stamen number and awn characteristics. However, these structures are deciduous and frequently absent in the mature espikelet, which makes their identification difficult. In order to recognize useful characters for species delimitation, this paper studied the leaf blade anatomy and ultrastructure. The different characteristics between these species were: prickle hair arrangement on the leaf blade adaxial surface; furrow depth on the adaxial surface; saliency shape on the first order bundle; vascular bundle size, position, and arrangement on the leaf blade; metaxylem vessel outline; number of cells in the bundle sheath extension; presence/absence of colourless cells in the mesophyll; number of chlorenchyma radiated cell strata and distribution of the sub epidermal scherenchyma. In both species, chloroplasts of the chlorenchyma show grana and absence of starch grains; those in the sheath are agranal, with or without starch grains. Other characteristics such as presence of epicuticular waxes, stomata in furrows on the adaxial surface, differences in the sinuosity degree of the epidermal cell wall, and cell wall structure are common in cerrado species and can be related to water saving.

Bulliform cells in Loudetiopsis chrysothrix (Nees) Conert and Tristachya leiostachya Nees (Poaceae): structure in relation to function

“…In addition, cell wall pectin could act as water reservoirs for the internal leaf environment, slowing down the drying rate. Under dry conditions, these substances with the epicuticular waxes observed by Alvarez et al (2005) might act as a barrier to retard the water loss. The vacuole characteristics observed in the bulliform cells could be associated with different physiological conditions of these cells.…”

“…Considering the taxonomic and likely ecophysiological role of bulliform cells, their structural details have been studied in few species (Tuan et al, 1965;Jane and Chiang, 1991;Vecchia et al, 1998). Loudetiopsis chrysothrix (Nees) Conert and Tristachya leiostachya Nees, two native grasses found in the rocky fields and cerrado (LonghiWagner, 2001), present leaf rolling under water stress and possess features as epicuticular waxes, silica bodies in the costal zone, and stomata in furrows that can be related to water saving (Alvarez et al, 2005). The aim of this work was to provide data about the anatomy and ultrastructure of bulliform cells of L. chrysothrix and T. leiostachya, which might be related to the leaf involution mechanism.…”

Fluazifop-P-Butyl Efficacy as a Function of Application Time and Herbicide Dose

“…Actually, when compared to other times of fluazifop application, the lowest leaf angle measured on U. plantaginea plants during the warmest parts of the day (11 a.m. and 4 p.m.) (Table 1) may be consequence of slightly rolled leaves, which acquired a more vertical position (low leaf angle). The leaves of grass plants contain bulliform cells on their epidermis, which promote their rolling and protect them against dehydration because reduce the surface area exposed to the atmosphere (Alvarez et al, 2005).…”

Anatomia foliar como subsídio à taxonomia de espécies do Complexo Briza L. (Poaceae: Pooideae: Poeae)

“…A análise da anatomia foliar também tem sido utilizada em outros níveis taxonômicos fornecendo vários caracteres constantes e diagnósticos. ( Metcalfe 1960;Ellis 1976;1979;López & Devesa 1991;Torres & Engleman 1995;Sánchez & Koch 1998;Vieira et al 2002;Kesler et al 2003, Silva & Alquini 2003Alvarez et al 2005;Ma et al 2005;Finot et al 2006;Guevara & Ramia 2007;Kharazian 2007).…”