Embedded Player Around the country, it's the time of the year when people get together to pull garlic mustard from the ground. It's an invasive plant that spreads quickly and threatens native ecosystems. Jason Frenzel, an outreach coordinator for the Natural Area Preservation Unit in Ann Arbor, Mich., is leading a group of volunteers to yank the weeds from parks and woods on Saturday. He talks with Melissa Block about "Weed-Out Day."