Stomata in Mexican Oaks (Quercus: Fagaceae)


Foliar Micromorphology of Mexican Oaks (Quercus: Fagaceae)

by Scareli-Santos C., Sanchez-Mondragon M. L., Gonzalez-Rodriguez A., Oyama K. (2013)

Claudia Scareli-Santos, Universidad Nacional Autónoma de México

María l. Sánchez-Mondragón, Instituto Tecnológico de Morelia, Mexico

Antonio González-Rodríguez, Universidad Nacional Autónoma de México

Ken Oyama, Universidad Nacional Autónoma de México


1Universidad Nacional Autónoma de México, Centro de Investigaciones en Ecosistemas, Antigua Carretera a Pátzcuaro Núm. 8701, Colonia Ex-Hacienda de San José de la Huerta, 58190 Morelia, Michoacán, México. (Scareli-Santos C. and Gonzalez-Rodriguez A.)

2Instituto Tecnológico de Morelia, Avenida Morelos Norte Núm. 1500, Colonia Santiaguito, 58110 Morelia, Michoacán, México. (Sanchez-Mondragon M. L.)

3Universidad Nacional Autónoma de México, Escuela Nacional de Estudios Superiores Morelia, Antigua Carretera a Pátzcuaro Núm. 8701, Col. Ex-Hacienda de San José de la Huerta, 58190 Morelia, Michoacán, México. (Oyama K.)



in  Acta Botanica Mexicana 104: 31-52


Mexico is the main center of diversity of the genus Quercus in the Western Hemisphere. Despite recent advances in the knowledge of Mexican oaks, a degree of taxonomic confusion still remains, mainly within particular species complexes.

In this study, scanning electron microscopy was used to describe micromorphological foliar structures (trichomes, epicuticular waxes and stomata) from the abaxial and adaxial leaf surfaces of Mexican oak species, with the main goal of assessing the taxonomical utility of these characters.

In total, 27 species belonging to sections Quercus (white oaks) and Lobatae (red/black oaks) were examined, particularly focusing on several groups of closely related species with problematic taxonomic delimitation and on species that are known to hybridize.

Several trichome types were observed, including both glandular (simple and bulbous) and eglandular (solitary, multiradiate, stellate, fused stellate and fasciculate stipitate).

Epicuticular waxes were structured as lms, grooved lms, crusts, granules, platelets and platelets arranged in rosettes.

Stomata were elliptical and raised above or leveled with the foliar surface.

Among the three types of structures examined, trichomes appeared to be the most useful for taxonomical purposes, followed by epicuticular waxes.

All species had different combinations of character states for these micromorphological structures, which permitted the elaboration of keys to identify species within the problematic groups.

Figs. 9-16. (S = stomata, ST = simple trichomes, SteT = stellate trichomes, WC = epicuticular wax crust, WF = epicuticular wax lm, WG = epicuticular wax granules, WP = epicuticular wax platelets). Figs. 9, 10. Quercus resinosa Liebm. (abaxial and adaxial surface respectively). Fig. 11. Quercus acutifolia Née (abaxial surface). Fig. 12. Quercus af nis Scheidw. (abaxial surface). Fig. 13. Quercus coccolobifolia Trel. (abaxial surface). Fig. 14. Quercus conzattii Trel. (abaxial surface). Figs. 15, 16. Quercus crassipes Humb. et Bonpl. (abaxial and adaxial surface, respectively).



Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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