Mining engineer, botanist, and Latinist from Ohio who grew up on a farm in Grinnell, Iowa and trained in languages and classics at Grinnell College. He moved to Salt Lake City, Utah (1880) where he taught himself geology, botany and chemistry and made his living in mining, exploring the Intermountain West in his Model T Ford. He made extensive botanical collections and discovered many local endemics. During his later years he was based in southern California at Pomona College, providing him with an academic base from which to explore the western United States and adjacent parts of northern Mexico. He started his own journal Contributions to Western Botany in order to publish his many botanical discoveries. Marcus Jones died in a fatal car accident while returning from a field trip to the San Bernardino Mountains. His printed labels give his name as 'Marcus E. Jones A.M.' and he sold his private herbarium (1923) of some 100,000 specimens to Pomona College (POM). The genus Jonesiella Rydb. (Fabaceae) was named in his honour.