Euphorbia geyeri Engelm. var. geyeri
Family - Euphorbiaceae
Stem - Prostrate, to 25 cm, branched, loosely mat-forming, tan to yellowish green to pinkish, glabrous.
Leaves - Leaves opposite, sessile or nearly so, to 12 mm, oblong, rounded and slightly asymmetric at base, entire, glabrous. Stipules small scales 0.7-1.5 mm long, sometimes fused toward the base, mostly deeply and irregularly fringed or lobed.
Stem and leaves.
Inflorescence - Axillary, solitary cyathia.
Flower - Involucre to 1.5 mm, glabrous. Marginal glands 0.2-0.6 mm, greenish, with inconspicuous petalloid appendage, this white or pinkish. Ovaries glabrous, the styles 0.2-0.5 mm long, each divided 1/3-1/2 of the way from the tip into 2 slender lobes. Fruits 1.5-2.0 mm long, glabrous.
Flowering - July - October.
Habitat - Sand prairies.
Origin - Native to the U.S.
Other info. - This small and inconspicuous species is rare in Missouri, and in fact is state listed as S1 (critically imperiled). It is found only in areas of deep sand which support few other species to compete for space and nutrients. It is a flowering plant, but like other members of the genus, its flowers are minute and clustered into highly modified units called cyathia.
Photographs taken near Blodgett, Scott County, MO, 8-28-2015 (SRTurner).