The genus Euphorbia, commonly called Spurge has always been a curiosity to me and the more that I learn about this group, the more intrigued I become! It is a huge genus, containing 2,008 species whose native habitats range from the deserts of Africa and the Americas to the woodlands of Europe. One species that I have enjoyed immensely for its tough constitution and multi-seasonal interest is the evergreen Wood Spurge, Euphorbia amygdaloides. It not only provides a spring floral display, but lush evergreen foliage in dry shade throughout the remainder of the year!
Euphorbia is in the family Euphorbiaceae, with upwards of 7,500 species. The genus name was initially penned by King Juba II of Numidia (50BC-23AD) who married the daughter of Anthony and Cleopatra. It honors his personal physician Euphorbus, who evidently made a laxative from the sap of the plant, now named Euphorbia resinifera. In 1753, Linnaeus officially adopted Euphorbia as the genus name. The species epithet is from the Greek Amygdalus, which means almond and refers to the similarity of the shape of the leaf to that of an almond. The common name of spurge is from the old French espurgier, meaning to purge and refers to the sap’s use as a purgative or laxative! As a genus, Euphorbia is united by several unique qualities. One is the flower. Spurges are monoecious, meaning one plant bares separate male and female flowers. Unique to this genus, both sexes of the flower are combined together into a specialized structure called a cyathium or cyathia if plural. A cyathium consists of 5 tiny leaves called bracteoles that are fused to form a tiny vase. Located in the center and extending beyond the top of this vase is the female flower. This in turn is surrounded by 5 male flowers, one for each bracteole, which consists of simply one anther on a stem. Cyathia also contain 1 to 10 nectar glands which appear on top of the bracteole ‘vase’ and are often brightly colored. Typically, the cyathia are clustered together in pairs or clusters. Notice there was no mention of petals! Spurges rely on a ring of brightly colored leaves called bracts that subtend the cyathia – a well-known example of which is Euphorbia pulcherrima, the Poinsettia! Another unique quality of Euphorbia is the sticky, milky white sap. Its true purpose is to prevent predation and indeed it works as Spurges are deer resistant! Unfortunately, for some the sap also induces a dermal response similar to poison ivy.
Euphorbia amygdaloides is native to Europe, West to the Caucasus and South to Turkey. The plants self-sow and form colonies that bloom from late March through May! The 12-14” tall stems are tipped with tiny flowers perched upon 1” diameter chartreuse bracts, creating a wonderful show! The nice quality about chartreuse is that it can be paired with almost any color, allowing it to be the perfect complement to the spring garden! Two nice forms that have been in the trade for a number of years include the cultivar ‘Purpurea’ and the variety robbiae. ‘Purpurea’ has whorled, 2” long lance shaped leaves along the stems that are colored a deep, reddish purple. This provides the perfect backdrop come spring for the bright chartreuse floral bracts and it also seeds true! The variety robbieae is commonly known as ‘Mrs. Robb’s Bonnet’. It features densely whorled dark green, almond-shaped foliage on suckering and spreading stems that complement the bright chartreuse floral display. In addition, it has a fun story! Mary Anne Robb (1829-1912) was a British plant explorer who evidently discovered this plant in Turkey, although it has never been seen since in the wild. In order to get it through customs, she supposedly hid it in a hatbox or beneath her bonnet, hence the common name.
Hardy to zone 5 gardens, it is best protected from the late day sun during the winter months and planted in well-drained soils. Wood Spurge provides a wonderful mat of deep green foliage throughout the year with the wonderful promise of bright chartreuse ‘flowers’ come spring. Certainly, a Woodland Gem!