Ulmus americana American elm

Fringed samaras, a distinctive feature of the American elm; Paco Drive, Los Altos. Sairus Patel, 24 Feb 2022

American elms, once much cherished for their graceful vase-shaped crowns, which can form cathedral-like canopies over streets, have been devastated by Dutch elm disease. A stunted specimen beneath the overhead power lines at 607 Paco Drive in Los Altos was the only verified American elm in the area until it was removed in 2026. All other purported survivors on campus or in Palo Alto, including one at 4229 Ponce Drive listed as a city heritage tree, have turned out on examination to be English elms. Telling the two apart means waiting for the right time in spring: the American has a delicate fringe of hairs along the edges of its flat fruits, which develop rather quickly from the small flowers, whereas the fruit margins of the English are smooth.

Name derivation: Ulmus – classical Latin name for the elm.