Euphorbia commutata Engelm.

Euphorbia commutata plant

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.

Euphorbia commutata leaves

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.

Euphorbia commutata flower

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.
I photographed this plant on a steep rocky slope down in Taney County near sunset, hence the slightly fuzzy pictures. I have seen it growing mostly in very rocky conditions, which it seems to tolerate well. The leaves and stem turn bright red as the plant starts to age.

Photographs taken in the Hercules Glade Wilderness, Mark Twain National Forest, Taney County, MO., 5-19-00.