In their rapid colonization of soil exposed by fires, floods, and grazing animals, weeds resemble the human specialists we label Emergency Medical Technicians (EMTs). Weeds are the first responders when disasters occur in nature. They occupy bare soil and prevent erosion by wind and water. In extreme cases such as a landslide, weeds are essential to the healing processes that replace the lost soil. Like a Band-Aid on a skinned knee, weeds protect the land while it recovers. Besides protecting the soil after disaster, weeds provide food for wildlife, and some of them provide food and medicine for people. Able to withstand harsh conditions, weeds will proliferate as global warming and other human impacts intensify. Thus, nature’s EMTs will increase while all other plants decline. The book provides a succinct definition of weeds according to their form and function in ecosystem processes. The narrative uses a representative set of weed species from a desert location to illustrate the full range of weed characteristics.