XVI International Botanical Congess

Tidestromia consists of eight species, most of which are endemic to the Chihuahuan Desert. The group has been scarcely studied and there is no a monograph of the genus. The present work includes general morphological descriptions of the species of Tidestromia as a first step towards completion of a taxonomic monograph. Six kinds of trichomes were described through the use of Stereoscopic Microscope and Scanning Electron Microscope. Pollen surface sculpturing was studied through the use of SEM. Pollen characters separate Tidestromia from putative genus and morphological pollen differences among the species were primarily quantitative. Leaf venation was described based on clearing techniques. Venation pattern was the same in all the species but some differences between arrangement of veins helped to discern between leaves and inflorescence bracts.