The word Wednesday comes from Old English: Wōdnesdæg, meaning ‘day of Odin.’ Odin, or Woden, is a Germanic god who's been equated with the Roman god, Mercury. The two are both linked to communication between the earth, the underworld and the heavens, as well as with healing and the written word.
In ancient Mexico, the Aztec god Huitzilopochtli, had the hummingbird as his animal and was sometimes depicted as one. In some present day Mexican tribes, hummingbirds- like Odin and Mercury- are believed to be messengers from the afterworld or of spirits of those who have crossed over.
Costa's Hummingbird is found in the Mojave Desert. Along with Purple Owl's (Clover) and Desert (Lavender), you can read about more plants associated with Mercury (and why) at Anima Mundi Herbal's blog! Just search for 'Mercury.'