Plants of the Eloise Butler Wildflower Garden

Flowering Spurge grows up to 3 or 4 feet high; the bright green stem is unbranched below the inflorescence. Juice of the plant is milky and acrid, as in most spurges.

Leaves are alternate on the lower stem and just below the inflorescence is a distinctive whorl. They are oblong, up to 5/8 inches wide and 6x longer than wide, sessile or with very short stalks. There is a prominent mid-vein, the top side is a medium green, the underside paler in color due to very fine surface hair. In autumn the leaves and stem can pick up a very colorful pinkish-red to scarlet color.

The inflorescence is a many-branched loose panicle above a distinctive whorl of leaves. The panicle usually has 5 main branches but six branches are not uncommon. The number of leaves in the whorl beneath the inflorescence also varies, many times there are six, sometimes only 5 and when the main branching is 6 branches there is usually a 7th. Each main branch of the panicle can repeatedly subdivide, usually into fewer branches than the division below it, but sometimes repeating, until only 1 branch remains - i.e. 5 then 4 then 3 then 2 and sometimes one. This is not rigid, 4 seems to be skipped a lot, 3 and 2 seem to be repeated a lot. Branching may stop at any point without getting down to 1. Subtending each of these divisions is a set of small leaves, usually, but not always, equal to the number of divisions, ending with one under a single flower. The flowers are all terminal - at the end of the branch that does not divide any further. See the photo below for an illustration.

Flowers: The small 1/3 inch wide flowers are of a structure unique to the Euphorbia genus. The flower parts are grouped together in a structure called a cyathium. Inside at its base are 4 to 5 nectar glands (greenish-yellow in this species) and these have outward flaring appendages that look like white petals but are instead white bracts. The underside of all this looks like a cup. From this base around the nectar glands appear the male flowers which have one stamen each with a yellow anther. Arising from the center of the cyathium is the stalk of the female flower, which has a green 3-lobed ovary with 3 divided styles emerging. The nectar glands turn reddish as the flower matures.

Seed: Fertile flowers produce 3 oval brown seeds that are released when the dried ovary splits open. Seeds require 30 days of cold stratification for germination. The plant will self-seed.

Toxic: The milky latex juice of the plant has toxic effects on humans and animals. Foraging on the plant has been known to be deadly to animals. There is some concern that the toxin is carcinogenic to humans. Kinghorn, in his book, Toxic Plants (Ref. #15), devotes an entire chapter to the carcinogenic and irritant properties of the Euphorbiaceae.

Habitat: Flowering Spurge grows best in full sun with dry to moderate moisture in loamy soils. It will tolerate partial shade. It grows from a deep woody taproot which makes it hard to eliminate, but it is a beautiful plant.

Names: The genus name, Euphorbia, is said to refer to Euphorbus, the Greek physician of King Juba II of Numidia. Euphorbus found medicinal uses of certain plants of this genus. Carl Linnaeus named the genus after him. The species name, corollata, is Latin meaning 'like a corolla', referring to the appendages of the nectar glands that look like the petals of a normal corolla. The author name for the plant classification - 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.

Comparisons: Another Euphorbia found in Minnesota that has a yellow inflorescence is the non-native invasive Leafy Spurge, Euphorbia virgata. Also look at the Wild Poinsettia, Euphorbia cyathophora.