Invasive plants add to the stress on the San Mateo woolly sunflower population .
The San Mateo County colony is subject to damage by dumping of residential garden debris and downhill surface runoff of pesticides and fertilizers from homes above the steep - sloping habitat along Crystal Springs Road .
Invasive plants add to the stress on the San Mateo County   woolly sunflower population .
The San Mateo County colony is subject to damage by dumping of residential garden debris and downhill surface runoff of pesticides and fertilizers from homes above the steep - sloping habitat along Crystal Springs Road .