The teeming plant world could become a virtual mystery in the coming decades as college students increasingly shy away from studying botany and universities across the U.S. shutter their long-standing herbaria. Since 1988, the number of research universities offering botany degrees has dropped by half, according to National Science Foundation research funding statistics. And the National Center for Education Statistics reports that fewer than 400 undergraduate, graduate and doctoral botany degrees were awarded in 2012. Educators say that’s because students are being pushed into more modern, technology-related majors. Current botanists fear that will lead to a dearth of people able...