Here it is, the Tiburon Mariposa Lily. Well worth a trip up Ring Mountain. You will also see Turtle Rock. If all this seems familiar to you, it is because Bob H and I took pictures up there last year. Rather than use my own words I quote ~
From the Marin Chapter California Native Plant Society ~
Our logo is the Tiburon Mariposa Lily
(Calochortus tiburonensis). This extremely rare lily can be seen blooming from the end of May through mid-June among the serpentine rocks of Ring Mountain in Marin County, California. In fact, this is the only place in the world it has ever been found growing in the wild. It was first noticed by botanists in 1971 when the small patch of land on which it lives passed from private into public hands. The plant is now in cultivation and can be seen in botanic gardens.
(Calochortus tiburonensis). This extremely rare lily can be seen blooming from the end of May through mid-June among the serpentine rocks of Ring Mountain in Marin County, California. In fact, this is the only place in the world it has ever been found growing in the wild. It was first noticed by botanists in 1971 when the small patch of land on which it lives passed from private into public hands. The plant is now in cultivation and can be seen in botanic gardens.
One more thing about the excursion. We parked at the top of Reed Ranch Road, across the street from a gigantic mansion that looks like a medieval castle. Complete with turrets and barking dogs, a sight to behold. Probably the home of a family of three or four, when they're not touring the French Riviera! Fortunately Marin County churches are providing shelter to a few of the homeless.