Just because Marin Flora was recently revised (in 2007) doesn't mean that new species of plants cannot be discovered, possibly by any of you. The drying shores of Stafford Lake reservoir, west of Novato, have offered unusual-for-Marin flowers even in late summer and fall.
"In the drying marshes of Pt. Reyes, such as along the western parts of the Abbotts Lagoon trail, marsh goldenrod, Solidago elongata, is often abundant in early September. It is often seen flowering in showy yellow masses. The inflorescences are much larger than those of the other two true goldenrods of Marin County, Solidago spathulata and Soldago velutina ssp. californica.
This is one of the rarest plants in the world now found as a natural population only on Point Reyes National Seashore. There is some doubt that the original type specimen really came from Sonoma County and it is possibly a Marin endemic. Sonoma botanists need to check for it near Duncan's Mills to refute this statement!