"Trees for which there is no commercial value are referred to as "weeds" that interfere with commercial harvesting. That's what alders were called until a method to make high-grade paper from them was developed, but you'd never know that alders play an important ecological role. They are the first trees to grow after an opening is cleared in a forest, and they fix nitrogen from the air to fertilize the soil for the later-growing, longer-lived, bigger tree species. Yew trees have tough wood with gnarled branches and were called weeds and burned until a powerful anti-cancer agent was found in their bark."