Mexia embarked on her first major botanical expedition to western Mexico, collecting 1,500 specimens.
Ynés Mexia started her professional journey as a botanist on September 23, 1925, by joining a Stanford University-led expedition to western Mexico. Under the guidance of botanist Roxana Ferris, this expedition marked her first major foray into plant collecting. Despite beginning her career later in life, Mexia's dedication and expertise on this trip resulted in the collection of about 1,500 specimens, including the first plant named after her, Mimosa mexiae. Her work during this expedition set the stage for her future contributions to botany.