Palmeras fósiles del norte de México

Abstract

EIGHT NEW PALMS FROM NORTHERN MEXICO ARE DESCRIBED AND COMPARED WITH STEMS, ROOT AND PETIOLES OF FOSSIL AND EXTANT PALMS. FIVE PALMS ARE REPRESENTED BY THEIR STEMS, TWO BY THEIR ROOTS AND ONE INCLUDES STEM, ROOT AND PETIOLE. THE STEMS OF THE NEW PALMS ARE DISTNCT AMONG EACH OTHER IN THE RADIAL DIAMETER OF THEIR VASCULAR BUNDLES, THEIR FIBER-VASCULAR RELATIONSHIP, AND THE PRESENCE/ABSENCE OF FIBERS AND/OR PARENCHYMA CELLS SURROUNDING THE VASCULAR REGION OF THE VASCULAR BUNDLES. THE ROOTS CAN BE DISTINGUISHED DUE TO THE PRESENCE/ABSENCE OF A HYPODEMIS, CELL ARRANGEMENT IN THE MIDDLE CORTEX, AND NUMBER OF METAXYLEM VESSELS ALONG WITH THEIR, PRESENCE/ABSENCE IN THE PITH. THESE NEW PALM REPORTS TOGETHER WITH OTHER PREVIOUSLY PUBLISHED PALM VEGETATIVE ORGANS FROM SOUTHERN MEXICO MAKE A TOTAL OF 13 FOSSIL PALMS THAT ARE DIFFERENT FROM THE EXTANT PLANTS WITH WHICH THEY HAVE BEEN COMPARED. ALTHOUGH THEIR AGE VARIES FROM CRETACEOUS TO OLIGOCENE/MIOCENE AND THEIR GEOGRAPHIC DISTRIBUTION IS WIDESPREAD, E.G. BAJA CALIFORNIA SUR, SONORA, COAHUILA AND NUEVO LEÓN, PRELIMINARY OBSERVATIONS SUGGEST THAT SOME OF THESE PALMS HAD AN ARBORESCENT HABIT WHILE OTHERS WERE HERBS, THEREFORE, THEIR GROWTH HABIT AND ROLE IN THE COMMUNITY MAY BE COMPARABLE TO THAT OF SOME EXTANT MEMBERS OF THE GROUP.