Lessingia ramulosa (Sonoma lessingia) is a plant species endemic to California. It is known only from the area around Crystal Springs Reservoir in Sonoma and San Mateo Counties north of San Francisco. It grows in marshes and woodlands, sometimes on serpentine soil. Lessingia ramulosa is an herb up to 50 cm tall. It has persistent basal leaves plus leaves on the stems. Flower heads are borne singly at the ends of branches, with lavender flowers.