Cypress spurge (Euphorbia cyparissias) has narrow green leaves, 1.5 inches long, crowded densely on the stems, looking like tiny evergreen branches — but they feel soft. The plant grows in billowy, foot-tall mounds of these feathery stems. In spring the ends of stems grow tiny yellow-green flowers, surrounded by yellow-green or orange bracts and arranged in clusters.

I bought and planted two, then looked on the Web to learn more than the bare facts on the tag. I was dismayed.

This deciduous perennial, native to much of Europe, was introduced to North America in the 1860s for its decorative appeal. But it escaped cultivation, and became invasive. From its popularity as a headstone planting, it became known as “the graveyard weed.”

On fertile plants, fruit becomes an explosive capsule that throws its seed up to fifteen feet. The plants make taproots up to nine feet deep, and extensive horizontal roots too, sprouting new plants up from them. They regrow from small pieces of root. Both mowing and burning the plants stimulate growth.

In open land it spreads rapidly, crowds out other vegetation and also poses a health hazard. The thick, milky sap (“latex”) is deadly to horses and cattle, and in humans irritates skin, eyes, mouth, and gastrointestinal tract.

My pretty plant is a major pest in the Northeastern US, Quebec and Ontario. The Nature Conservancy’s Massachusetts Islands Program is fighting a severe infestation in the Katama Plains preserve, one of the world’s few remaining sandplain grasslands. Ecologist Kendra Buresch says they can’t use herbicides because the euphorbia grows lower than many of the native plants they want to keep there.

Buresch may introduce some European root-eating beetles that appear to feed only on certain euphorbia. Beginning in 1995, after studies to determine the beetles won’t attack any valuable species, the US Depratment of Agriculture has released them in New Hampshire, New York and Rhode Island, as well as western states.

The euphorbia cultivar I bought, ‘Fen’s Ruby’, is slightly bluer of leaf than the species E. cyparissias, with a crimson flush on new growth. I gazed wistfully at the one that was next to a ‘Midas Touch’ feverfew, which has bright chartreuse foliage: together they made a gorgeous contrast.

But the euphorbia was too close, and growing faster. I don’t need another monster trying to take over my yard. Gritting my teeth, I dug up both euphorbias, bagged them and put them in the trash.

• Cypress Spurge, by H. Faubert and R.A. Casagrande, Department of Plant Sciences, University of Rhode Island, Kingston, Rhode Island — on the site of Invasive Plants of the Eastern US, from Biological Control of Invasive Plants in the Eastern United States, edited by Van Driesche, R., et al.: USDA Forest Service Publication FHTET-2002-04.
• Euphorbia cyparissias, on the site of IPANE, the Invasive Plant Atlas of New England
  • also there: a good photo of the plant's rhizomatous propagation
• Euphorbia cyparissias, message #3 on The Nature Conservancy's Invasive Species ListServe Digest #010, Wed, 6 Jan 1999 17:17:09 -0800 (PST)