Stinkwort, Stinkweed, a stinky weed by any name

Stinkwort - not only does it smell very bad, but
it can cause dermititis and diarrhea.  

Stinkwort.

You can't avoid running into it where ever you go. In Fremont, I see it along side the road here and there, at the California Nursery Park, at Coyote Hills, at Ohlone College. You can identify it 65 miles per hour along the freeway. It's one of the only green plants at this time of year.

In August and September, in our hills in the Mission Peak Preserve, the sticky monkeyflower is burnt to a crisp, the California Fuchsias are still hanging in there, and we see various kinds of flowers in the Asteraceae family (what I used to call a "comp"..."daisy" flowers to others). It's nice to visit the native plants that are blooming at this late time of year.







In late September 2009, we were on our way to visit our favorite Madia elegans patch farther up the hill in Mission Peak Preserve to see how they were growing.  Madia elegans is a tarweed that has a nice pineapply smell. I really really really like it. My icon is a Madia flower

Madia elegans, Elegant Tarweed

Another bloomer in the Asteraceae

On our way up, this day in 2009, we happened upon some very lush green plants behind Ohlone College and they were the only green plants growing around. This mystery plant looked vaguely like a tarweed of some kind.  They were sticky, growing up in between the cracks of an asphalt road. Really impressive in their robustness. At first, I kind of liked the smell, but there was something aggressive about it. There is an element in its smell that really knocks your socks off. A little research and I found that it was Stinkwort, Dittrichia graveolens.

QUESTION: You aren't supposed to name plants after yourself. So that means that someone named this stinky rashy plant after someone else! Would you name a stinky plant after someone you liked? Who is the 'lucky' person who has their name attached to such a stinky plant, Dittrichia graveolens?

ANSWER: I checked Calflora's "California Plant Names: Latin and Greek Names and Derivations". Here's what they said:

• Dittrich'ia: named for the German botanist Manfred Dittrich (1934- ), a specialist in Asteraceae at the Herbarium of the Geneva, Switzerland, Conservatory and Botanical Garden and later Director of the Herbarium of the Botanic Garden and Botanical Museum Berlin-Dahlem (ref. genus Dittrichia)
• graveo'lens: strong or ill-smelling (compare beneolens, suaveolens)

So it means "Stinky Dittrich". I hope Manfred doesn't mind! If it were named after me, I'd be hoping it has a chemical that could be used to cure cancer or eradicate bed bugs or show us how to grow stuff without water. Then I'd have the last laugh.

Speaking of chemicals, someone did wonder what chemicals are in stinkwort, and the answer is: 90% of the total composition consists of oxygenated compounds. The four major components identified were bornyl acetate (about 70%), T-cadinol (about 8%), borneol (about 8%), and caryophyllene oxide (2%), in addition to 21 minor ones. So which of these is the stinky one? Bornyl acetate is "Pine, Camphoraceous, Herbal, Balsamic". T-cadinol is "extract of scented myrrh". Borneol is "piney camphoraceous". Caryophyllene oxide is the component of marijuana that marijuana-sniffing dogs detect. It is also present in lemon balm and Melaleuca stypheloides. All of those sound okay, maybe in large quantities one of them is overpowering. Or maybe one of the 21 minor chemicals is the over-powering scent. Another article found these components: among 22 components were 1,8 Cineol (AKA eucalyptol, about 55%), P-Cymen (is this the same as P-Cymene? If so, thyme and cumin seed oils contain P-Cymene (About 16%)), [beta]-pinene (About 7%) and Borneol (About 5%). Beta-pinene is an interesting oil - found in turpentine oil, and other essential oils as lemon, nutmeg, hyssop, coriander and cumin seed. Maybe the turpentine element is the sock-knocker.

(Another sock-knocker-offer plant is vinegar weed (Trichostema lanceolatum). Vinegar weed wins the prize for stink and it will wake you up from a dead faint. Maybe similar oils?)



Also many of these articles mentioned anti-fungal qualities and some were used in perfumes, so maybe Manfred Dittrich does get the last laugh.

The crew removing stinkwort from the edge of the road and from
cracks in the road. Lots of people asked us what we were doing.

Since 2009, we've been pulling it out periodically when we see it and disposing of it properly (not in compost). Then the other day, we were out at Coyote Hills, and there was Stinkweed all along the path, almost making a complete circle around the hills. All of them showing off their nice green foliage. Instead of reporting them here, I contacted the Coyote Hills park supervisor to see if it would be ok to work on pulling them weekly on our walks. We met with Jim Rutledge today to sign release forms.




How did Stinkweed get here?

The California Agriculture magazine article, "Stinkwort is rapidly expanding its range in California", says that it was first reported in Santa Clara County in 1984 near Milpitas. It is now in 36 of 58 counties in California. It is native to the Mediterranean, Europe, North Africa, Egypt, and to Afganistan. It has spread to the U.S., up into Europe, Austria, Australia, and South Africa.

The article has a colorful map showing chronology of the spread.

Could there ever be a situation where someone is unknowingly spreading stinkwort around California?

Is the Tumbleweed Snowman really a Stinkwort Snowman? Has this "most emailed" article generated a whole new seed bank of stinkwort spread through-out California? I remember reading this article and being appalled at the idea of making a snowman out of a tumbleweed. (so yeah, bah humbug) I will check it out this next Christmas. I did check the neighborhood and didn't see any stinkwort in that area.


Can a dog be trained to find stinkwort?

• Today's NPR sept 3.

References:

• BLM
• IPC - California Invasive Plant Council has additional links for invasive plants.
• Barron Park, Santa Clara County
• UC Davis Weed Report
• Town Mouse Country Mouse has an article on how to tell from other tarweeds. At Coyote Hills it is mixed in with Madia sativa (?), which is a really cute tarweed. Or maybe Holocarpha virgata. Gotta see how they smell. 
• Another Madia look-alike is Telegraph weed (Heterotheca grandiflora) that is currently blooming locally (Sept 12, 2013). We are seeing it on Driscoll Road next to the Hetch Hetchy water supply building. And the offramp from 680 south at Mission, just over the grade. And ironically, it is an invasive plant in Australia and Hawaii. That particular link has an excellent set of pictures to help identify it. We smelled it and it has an odor, but not strong. Still thinking of what it reminds us of.