Douglas Iris noxious weed?

Yep, it appears that it is.

I was looking through noxiousweed_ratings.pdf on the California Dept of Food and Agriculture website and was surprised to find "Iris douglasiana Herb." with a rating of "C". (Simplistically speaking, noxious weeds are rated A through C. A = worst, B = worse, C = bad. Q rating is a provisional A rating.)

Since Iris douglasiana is a native plant, I wondered how it could be on the CDFA noxious weed list. Here's the answer::

"species are native to California and under most circumstances are not troublesome weeds. However, in highly disturbed places, such as heavily grazed meadows and some forestry sites, these hardy plants can aggressively proliferate and form extensive, dense stands as other native plants decline. Leaves and rhizomes are toxic if ingested, but rarely consumed by livestock because of the bitter taste."

So there you go. Native plant or noxious weed. You make the call.

"A" – Eradication, containment, rejection, or other holding action at the state-county level. Quarantine interceptions to be rejected or treated at any point in the state. This weed hasn't yet escaped to the point where we've given up on it, so perhaps we can nip it's spread in the bud, so to speak.

"B" – Eradication, containment, control or other holding action at the discretion of the commissioner. If we have extra volunteers, let them work on this weed.

"C" – State endorsed holding action and eradication only when found in a nursery; action to retard spread outside of nurseries at the discretion of the commissioner; reject only when found in a cropseed for planting or at the discretion of the commissioner. This one got away from us and it's naturalized so much that we're mostly ignoring it now.


  1. Thanks for the clarification. So, overgraze the land, thus suppressing all the nice nutritious grass and forbs, well of course the iris moves in once competition is removed.

    Seems to me that the noxious weed categories are quite suspect. Who got iris douglasiana listed in the first place? Cattle ranchers who wanted to apply herbicide on BLM land? -- just a wild guess.


  2. Great post you have here.
    Iris douglasiana is a beautiful plant, and it's sad to see it listed as a noxious weed.
    Because this iris is unpalatable to cattle, the State of California should be using it as an "indicator species" to tell them when over-grazing is happening, so grazing can be restricted to allow the land time recover.
    Another example of an indicator species, in different states, is Helenium bigelovi. It is native to parts of the Rocky Mountain states, and is also unpalatable to livestock. Areas where it occurs in abundance also indicates over-grazing.
    See: http://en.wikipedia.org/wiki/Overgrazing