Eriastrum densifolium is a species of flowering plant in the phlox family known by the common name giant woollystar.

It grows on an erect stem with slightly hairy to densely woolly foliage, often giving the plant a dark gray-green color.

The top of each stem is occupied by a bunched inflorescence full of woolly leaflike bracts and funnel-shaped, flat-faced flowers.

The lobes are white to bright, striking blue, sometimes with longitudinal pinstripes.

[1] A resident of higher floodplain habitat types, the plant was expected to suffer from the construction of the Seven Oaks Dam, which would alter the hydrology of the Santa Ana River waterways it depends on.