San Mateo Thornmint (US Native)
It's scientific name is the Acanthomintha duttonii. It's a very strong-scented annual herb. They grow on grassy serpentine hillsides that occur infrequently along the east side of the San Andreas fault, parallel to the coast of California. Germination occurs from November to December, the leafing in mid-March, and the budding in late March. They are thought to be insect-pollinated, most likely from bees.
Link #1: https://books.google.com/books?id=wFdWlrnz_uoC&pg=PA1485&lpg=PA1485&dq=san+mateo+thornmint+background+information&source=bl&ots=yuPvvUMMZP&sig=7wN7Zm2IjRyOZayfPskQ9ZHJtCQ&hl=en&sa=X&ved=0ahUKEwijkIqE5NDJAhWDWCYKHXR2DfoQ6AEINzAE#v=onepage&q=san%20mateo%20thornmint%20background%20information&f=false
Reasons for Endangerment and Attempts to Restore them:
They were severely damaged by off-road vehicles, weather patterns in the 1980s, blockage of a drainage culvert, which prevented natural water flows to get to the plants. There is a foundation raising money to help restore these plants called the San Mateo County Parks Foundation. The parks that have found clusters of the plant are keeping their exact location a secret in order to protect them.