Pollen grain in Tamarix arborea var. arborea

Abstract

The diffusion in the Italian territory, as wild and cultivated plant, of T. arborea (Sieb. ex Ehrenb.) Bge. var. arborea resulted wider than us could be waited for (Venturella et al., 2007). T. arborea var. arborea is characterized by aestival inflorescences composed of racemes and vernal inflorescence simple. The racemes are not longer than 6 cm long and 5 mm broad (Baum, 1978). The species is not still well investigated from the anatomical (leaf, root and stem) and palynological point of view. Nair (1962) investigated the Indian species of tamarisks and reported for T. arborea the following concise description: prolate, 27 × 18 μm, type of pollen grains with irregular reticulum. In order to better characterize the pollen grain morphology of T. arborea var. arborea a number of racemes was collected in different localities of the Sicilian territory. The racemes were sifted out and then the pollen grains were fixed on slides with a drop of glycerine mixed with fucsine and observed under optical microscope. The presence of pollenkitt was observed in all the analyzed samples of T. arborea var. arborea confirming that pollination in tamarisks species is entomophilous. Besides the pollen grains were dehydrated and metalized in graphite and then observed to SEM. The pollen grains of T. arborea var. arborea are prolate, 22.5 x 12 μm, tricolpate with sexine thinner in the colpus and reticulate exine. The new description here reported will contribute to yield more taxonomic evidence in the genus Tamarix L. and in the investigated species too.