Illustrator: Sandy Long
Agrostis hendersonii is a rare species that grows below 600 m in clay or adobe, sometimes rocky, soils around the edges of vernal pools in Oregon and California.
Agrostis aristiglumis Swallen, known only from its type locality on the Point Reyes Peninsula, Marin County, California, is included here in A. hendersonii. It differs from A. hendersonii in having a palea up to 0.9 mm long, and a barely exserted panicle. The relationship of these to each other and to A. microphylla merits investigation. Their differences may be the result of the founder effect on inbreeding annuals.