Micromorfometria Foliar De Palicourea Rigida Kunth. (Rubiaceae) Em Ambiente De Cerrado E Campo Rupestre

Abstract

MICROMORFOMETRIA FOLIAR DE PALICOUREA RIGIDA KUNTH. (RUBIACEAE) EM AMBIENTE DE CERRADO E CAMPO RUPESTRERESUMO: Este trabalho teve como objetivo um estudo anatômico descritivo e quantitativo da estrutura foliar de Palicourea rigida Kunth. (Rubiaceae), espécie que ocorre em áreas de cerrado e campo rupestre. As observações anatômicas foram realizadas em folhas de material fresco ou fixado, tratadas segundo metodologias usuais em anatomia vegetal. Foram observadas as seguintes características: epidermes do pecíolo e da lâmina foliar uniestratificadas; presença de tricomas tectores, simples, unisseriados, próximos, ou sobre as nervuras; estômatos do tipo paracítico presentes somente na face abaxial da folha; mesofilo com parênquima paliçádico de uma só camada de células; parênquima esponjoso com sete a nove camadas celulares com formas irregulares e tamanhos variados; idioblastos cristalíferos, observados em todos os parênquimas do pecíolo e lâmina foliar; feixes vasculares, do tipo colateral; colênquima observado, subepidermicamente, no pecíolo e nervuras de maior porte, em ambas faces; o padrão geral de nervação da espécie é pinado, camptódromo, broquidódromo. As análises micromorfométricas revelaram diferenças significativas em todos os itens analisados, sendo as médias mais elevadas encontradas nas folhas das plantas crescendo no cerrado. Isto sugere que a influência de fatores ambientais pode ter modulado respostas morfológicas nas plantas, visto que o tipo e distribuição dos tecidos não sofreram alterações nos dois ambientes. LEAF MICROMOPHOMETRY OF PALICOUREA RIGIDA KUNTH. (RUBIACEAE) FROM BRAZILIAN CERRADO AND CAMPO RUPESTRE ENVIRONMENTSABSTRACT: The objective of this work was to evaluate qualitative and quantitative leaf anatomical traits of Palicourea rigida Kunth. (Rubiaceae) species occurring in the Brazilian Cerrado and Campo Rupestre ecosystems. Anatomical analysis was performed in fresh or fixed leaves processed with usual plant microtechnique. Leaves showed uniseriate epidermis in petiole and leaf blade which contains uniseriate nonglandular tricomes (tector type) occurring only over the vascular bundles. Likewise, paracytic stomata were found only in abaxial side of the leaf surface. The mesophyll contains uniseriate palisade parenchyma and multiseriate spongy parenchyma (nine layers) which showed cells with different morphology and size. Crystal idoblasts of different types were observed in both the petiole and leaf blade. Collateral vascular bundles were found both in the petiole and leaf blade. Leaf venation type was pinnate, campylodromous or brochydodromous. The micromorphometric analysis showed significant differences from plants of different environments for all leaf characteristics and Cerrado plants showed higher means for all evaluated traits. Therefore, the influence of environments may had modulated morphological responses in P. rigida, since no difference was found in the type or distribution of leaf tissues in Cerrado or Campo Rupestre.

Comparative leaf anatomy of Baccharis (Asteraceae) from high-altitude grasslands in Brazil: taxonomic and ecological implications

“…All of the studied species present a thickening in the periclinal walls of the ordinary epidermal cells; a feature that is also found in other plants from high altitudes (Körner et al 1989;Gavilanes et al 2016). Such thickening can be an adaptation to the environmental conditions present at high altitudes, serving as a filter to reflect or absorb the high UV-radiation (Robberecht et al 1980), thus compensating for the thin cuticle layer observed in all of the studied species.…”

“…In addition to its contribution to taxonomy and systematics, the knowledge of plant anatomy can be useful for identifying local adaptations, when the environmental context is considered (e.g., Starr 1912;Hayden 1919;Metcalfe and Chalk 1979;Morretes 1980;Mott and Michaelson 1991;Somavilla and Graciano-Ribeiro 2011;Aguiar-Dias et al 2012;Jakovljevic ´et al 2014;Sanso et al 2014;Perrone et al 2015;Gavilanes et al 2016).…”

Leaf anatomy of Rubiaceae species in a semiarid area of Brazil

“…Some species demonstrated grouped stomata (described as twinned stomata by Accorsi [1947]) or malformed subsidiary cells; those finding agree with the studies of Mantovani et al (1995) and Gavilanes et al 2016. Accorsi (1947 reported the presence of twinned stomata in 39.45% of a total of 601 Rubiaceae species.…”