Family: Spurge (Euphorbiaceae)
Size: 0.25 in.
Notes: Ovaries are heart-shaped (bilobed), with small white triangles attached before flowers open. More than 3 dozen species of Euphorbia in Arizona.
This plant is found on the Appleton-Whittell Research Ranch Working Check list of flora.
Blackseed Spurge plant profile on the USDA Plants server.