WEED WATCHERS - Become a citizen scientist - a volunteer-based invasive plant early detection program. As a weed watcher you will learn to identify invasive plants of the region and report your findings. Weed Watchers patrol the roads and trails of the national parks in San Mateo, San Francisco, and Marin counties, detecting weeds as they first invade. Discovering weeds before they become well-established is critical to reducing damage to ecosystem integrity, preventing the loss of habitat for rare plants and animals, and preventing costly natural resource management. Deepen your understanding of the natural world while playing an important role in the protection of the unique resources at the park.