What is Euphorbia?
Commonly called spurge, Euphorbia is quite a large genus that includes anything from the iconic holiday plant, poinsettia (Euphorbia pulcherrima), to succulents, to those spotted spurges (Euphorbia maculata) that seem to sprout again as soon as you pull one. Additionally, this diverse genus can also mimic cacti in form and appearance due to convergent evolution. They are not related, however, but they tend to share many similar physical traits due to the hot and dry growing conditions of their natural habitats. With over 2,000 species, they comprise one of the most diverse groups of flowering plants on earth. As diverse as they are, they do all have one unique trait in common; all euphorbias emit a toxic, milky latex when cut and have varying different levels of toxicity.
Ironically, as with plenty of toxic plants, they have been historically used for medicinal purposes. The name Euphorbia dates to around 12 BC, when King Juba II of Mauritania named it after his physician, Euphorbus. The common name, spurge, is derived similarly, through Latin expurgare, which means to purge, cleanse, or purify, referring to its highly laxative properties. Spurges can be annuals, perennials, evergreen, deciduous, and even shrubs/trees, as observed in some of the other spurge specimens utilized in the gardens.
Most Euphorbia species originated in Africa, Madagascar, and the Americas. Their flowers feature unique cup-shaped structures called cyathia, which appear as a single flower but consist of several small flowers. They are often surrounded by modified leaves called bracts (like in the case of a poinsettia).
Euphorbia in the Gardens
The most abundant and prolific spurge we have in the Arboretum is Euphorbia corollata, or flowering spurge. This hardy North American native perennial is currently blooming plentifully in the Pollinator and Bird Garden, specifically in the Meadow Disc (the round bronzed circular structure in the center of the garden)! They have multiple bright-green stems that grow to 3 feet and produce clusters of small, white flowers that altogether create beautiful white clouds. All flowers in the Euphorbiaceae family are unisexual (only male or only female), and usually quite small.
The flowering spurge in the disc inside the Pollinator and Bird Garden is doing so well that Arboretum horticulturists are actively thinning it out to make space for other species to shine and prosper. It is quite literally stealing the show! The reasons it is doing so well are the same reasons why it is so popular within gardens; it is a tough plant that can handle poor soils and droughts and is hardy to USDA zones 3–9. Its pollinators include bees, wasps, flies, and butterflies, making the disc a very popular spot right now. Once the Euphorbia are done blooming, they continue to put on a show and provide an ecosystem service. Their leaves turn slightly red in autumn and provide garden interest until they are fully dormant in winter. Additionally, as with most Euphorbia species, their fruits are capsules that split open explosively when they are ripe. This helps them spread their seed to produce more beautiful plants!
Come visit these beautiful fluffy clouds before it’s too late! The Euphorbia in the Arboretum typically blooms between June and October with a peak July–August and can be found by searching our Arboretum Explorer Tool.
