Root anatomy of Venezuelan species of Geonoma (Arecaceae: Arecoideae: Geonomateae)

Abstract

In this research we studied root anatomy of eight species and two morphotypes from the genus Geonoma in Venezuela, in order to explore their structural and taxonomic implications. Fresh material sampled wild population was fixed in FAA and hand-sectioned or with a rotary microtome, following standardized protocols. Histochemical tests were carried out in some components. Obtained preparations were studied under a calibrated optical microscope; some variables were quantified by means of an eyepiece micrometer. The obtained results allowed the anatomical differentiation of the studied species and the two morphotypes. Most informative diagnostic variables identified include the thickening shape of the cells in the exodermis walls (transverse section), parenchyma cells with circular contours in the cortex, length of air spaces, the differentiation of passage cells in the endodermis, shared “V” and “Y” shaped xylem arches, the shape of phloem strands and scattered metaxylem vessels in the pith. Our results are also discussed in the context of other structural studies published on roots of different members of Arecaceae.