Eriophyllum latilobum or San Mateo woolly sunflower is a perennial herb of sharply limited range, endemic and occurring only in the state of California, USA. This flowering plant of the Asteraceae family has been listed as an endangered species by the U. S. federal government as well as the state of California. Eriophyllum latilobum has been found in San Mateo County, San Benito County, and Napa County in habitats of oak woodland, but at altitudes only between 100 to 150 meters. Eriophyllum latilobum grows to 90 centimeters in height on erect woolly stems and produces bright yellow flowers. Latilobum means "with wide lobe," from Latin latus, "wide". Like the other 13 species members of its genus, Eriophyllum latilobum presents generally alternate leaves ranging from entire to nearly compound. The flower heads are grouped in radiate, flat-topped heads, with an hemispheric to nearly conic involucre. Phyllaries are either free, or more or less fused, their receptacle flat, but naked and conic in the center. The ray flowers (the "petals") have yellow ligules entire to lobed. Fruits are 4-angled cylindric achenes in the outer flowers, but are generally club-shaped for the inner flowers; the pappus is somewhat jagged. Eriophyllum latilobum occurs as a subshrub between 20 and 50 centimeters in height. Its thin leaves are two to six centimeters in length, and have a diamond to obovate shape; the deeply triangular-lobed leaves are smooth on the top surface. The inflorescence's peduncles are one to eight centimeters and the involucres measure four to seven millimeters.