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Pikes/Pines | A surge of spurge in Capitol Hill gardens

Popping up here and there in gardens around Capitol Hill are the flowers of a plant that seems to have come from a Seussian landscape. With beautiful evergreen blue-green leaves and now topped with large clusters of striking chartreuse disks, these spurges (Euphorbia) are popular shrubs for adding a bit of dramatic flair to yards and planters.

The most commonly planted species is the Mediterranean spurge (Euphorbia characias), native to southern Europe, but several other species in the genus, including wood spurge (Euphorbia amygdaloides) are occasionally seen.

(Image: John Chau)

(Image: John Chau)

So what exactly are those chartreuse disks? Flowers would be the obvious answer, but take a closer look and they don’t appear quite like what one would expect.

A typical flower has petals, stamens (the male parts producing pollen), and a pistil (the female part producing seeds) inside. The spurge has something that looks similar, but each disk actually holds a collection of multiple flowers. The disk is a bract, or modified leaf, and above the bract are very small flowers and oftentimes a pair of additional bracts, each with its own cluster of tiny flowers. Each flower is highly reduced and consists of just a single small yellow stamen or a single green 3-lobed pistil. The unisexual flowers are surrounded by brown or yellow glands which produce nectar. This very unique arrangement of flowers is called a cyathium and is found throughout the genus Euphorbia.

You have almost certainly seen a cyathium before. The genus Euphorbia is among the largest in the plant kingdom with about 2000 species, and one of those is that favorite Christmas plant, the poinsettia (Euphorbia pulcherrima), which has cyathia above bright red bracts.

Another interesting feature of the spurge is found in the leaves and stems. When they are broken or damaged, they exude a milky-white and sticky sap that offers the plant protection against herbivores. The sap is toxic and irritating, and gardeners working with the plant should take care to avoid prolonged exposure on the skin. Milky sap, or latex, is common throughout the relatives of Euphorbia.

The latex of another species in the Euphorbia family, the rubber tree (Hevea brasiliensis), is tapped to make natural rubber.

 

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Christine H
Christine H
5 years ago

Capitol Hill Blog is the best – Everything I need to know from drug-over-dose deaths to riots to horticulture. There is nothing you don’t report on from our hill.

alan
alan
5 years ago

Thank you for something positive. Its good to remember some of the wonderful things that we have here on Capitol Hill, its not just demonstrations and traffic woes.

Allan W
Allan W
5 years ago

I must concur, this blog is awesome in its breadth and coverage. I might add a comment I learned the hard way about Donkeytail Spurge, a lovely gray-green trailing variety of Euphorbia. It is no longer sold in King County nurseries, and has been classified by King Co. as a ‘noxious weed”. The latex is caustic. While trimming mine, some latex splashed onto my eyelid. Much pain, two calls to Poison Control and a week later, I was healed. Luckily, the pain was never worse than a sunburn, but I was left with a new respect for the plant. An internet search will turn up many stories of unhappy gardeners or parents of children who recieved nasty painful chemical burns from the plant. One additional note, a common poisonous Euphorbia is our holiday Pointsettias.

John Chau
John Chau
5 years ago

Thanks for the thoughts! I’m glad you’re enjoying the series. Feel free to suggest any plants you want to read more about in the comments.

Jonathan Konkol
Jonathan Konkol
5 years ago

A friend of mine refers to these as “the Shrek plant”

pbe
pbe
5 years ago

I have the urge to spurge

Tatiana
5 years ago

ooh now I know, thank you! I’ve been enjoying photographing this wild interstellar life form this year. Things I find especially interesting: The shiny iridescent liquid that forms on them after a rain. How they look totally different when they are sprouting babies vs. when they are in full flower. The various stages of sprouting, with multiplying inner flowers. https://www.flickr.com/search/?user_id=86652386%40N00&tags=Euphorbia&view_all

RainWorshipper
RainWorshipper
5 years ago

Thank you for a lovely and informative article. I have often admired these weird and wonderful looking plants and wondered what they were.

y2karl
y2karl
5 years ago

”The latex is caustic…”

Allan W is right. I know of a gardener who was blinded by getting the sap of an overhanging one in her eyes. Spurges are not plants one would want to see in yards frequented by small children.