Euphorbia commutata Engelm.
Family - Euphorbiaceae
Stems - To +30cm tall, dichotomously branched, typically reddish at base, herbaceous, glabrous, erect, with milky sap.
Leaves - Lower leaves alternate, short-petiolate, spatulate to obcordate, emarginate, glabrous, falling near time of flower, smaller than upper leaves. Upper leaves (bracts) opposite, sessile, glabrous, reniform to broadly ovate, entire, emarginate or rounded at apex, to 1.5cm broad, 1cm long.
Inflorescence - Cyathia terminating stems in a dichasial arrangement.
Flowers - Involucre of cyathia 3mm long, glabrous. Glands of cyathia 4, yellow, 2-horned, flattened, 2-3mm long. Stamens 6, included in cyathia. Filaments flattened. Styles 3, bifurcate, .8mm long. Stigmas globose. Capsule 3-lobed, 1mm long in flower, expanding in fruit, one seed per locule.
Flowering - April - June.
Habitat - Ravines, rocky woods, valleys, streambanks.
Origin - Native to U.S.
Other info. - I've included this plant in the alternate leaved section because the actual leaves are alternate. The larger bracts of the plant in the inflorescence are opposite, so don't be confused.
Photographs taken in the Hercules Glade Wilderness, Mark Twain National Forest, Taney County, MO., 5-19-00.