Botanist and founder of <a href="https://blackbotanistsweek.weebly.com/">#BlackBotanistsWeek</a> Tanisha Williams explains why some leaves change color during fall and what shorter days and colder temperatures have to do with it. Plus, a bit of listener mail from you! (Encore) You can always reach the show by emailing <a href="mailto:shortwave@npr.org">shortwave@npr.org</a>. We're also on Twitter <a href="https://twitter.com/NPRShortWave">@NPRShortWave</a>! Learn more about sponsor message choices: <a href="https://podcastchoices.com/adchoices">podcastchoices.com/adchoices</a> <a href="https://www.npr.org/about-npr/179878450/privacy-policy">NPR Privacy Policy</a>

The Tigray Medical System Collapse

New discoveries, everyday mysteries, and the science behind the headlines — in just under 15 minutes. It's science for everyone, using a lot of creativity and a little humor. Join hosts Emily Kwong and Regina Barber for science on a different wavelength.If you're hooked, try Short Wave Plus. Your subscription supports the show and unlocks a sponsor-free feed. Learn more at plus.npr.org/shortwave