Arid and semi-arid zones make up about 50% of Mexico's land area; hence, the objectives of this study were (1) to undertake an inventory of fern and lycophyte species present in a region of central Mexico covered mainly by xerophilous
vegetation (Valle del Mezquital, Hidalgo); and (2) to analyze patterns of morphological variation of the species found with respect to environmental conditions.
The main vegetation unit in the Acarau River and its tributaries is dominated by Caatinga (a seasonal, xerophilous
thorn woodland/shrubland), and the area's climate is classified as tropical hot semi-arid (Maia et al.
It inhabits the Tepalcatepec Valley characterized by xerophilous
scrubland in the Balsas River Basin in the state of Michoacan.
Arid lands, including xerophilous
scrub and grassland, represent ca.
In addition to the above trees, xerophilous
and soil salinity resistant shrubs are found in the island which are mainly annual plants [10,14]