Tansy ragwort (Senecio jacobaea) - flowers, stems, leaves

Tansy ragwort, a native to Europe, Asia, and Siberia was first recorded on the California Pacific coast in 1912 and is believed to have spread through contaminated hay.  This vibrant, golden daisy-like flower which grows  in clusters atop branches connected to one central stem belongs to the sunflower family Asteracaeae.  This sturdy plant has fleshly roots that extend to about 1 foot deep, and a single plant is capable of producing over 150,000 seeds.  It thrives in the cool wet habitat of coastal areas. 

In Washington state where I live, there is an intense effort to eradicate Tansy ragwort.  It is a noxious weed, toxic to most grazing animals if consumed on a regular basis over an extended period of time.  While sheep appear to be least affected by its toxins, the poisonous alkaloids found in tansy ragwort have been discovered in some cow and goat milk, as well as in  honey produced by bees who forage these biennials.
  
Despite eradication efforts, my husband and I happened upon a grassy hillside completely covered with Tansy ragwort.  As we climbed the hill to harvest some plants for the dye pot, we found numerous matted places in the grass where Roosevelt Elk had bedded some nights before.  Their droppings were everywhere.  We peered into the nearby forest hoping to catch a glimpse of these magnificent animals, but they were nowhere to be found.

We went to work snipping flowers, and brought home a couple of arm loads, enough to fill my large enamel dye pot to the brim.

 
It was early evening when we returned home, so I just filled the pot with water and let it sit for the night.  In the morning, I brought the pot to a simmer and let it simmer for a couple of hours.  After straining the liquid into another pot, I entered a wet skein of yarn pre-mordanted with alum, along with a mordant sample card.  These simmered for about two hours.  Then I entered a second skein which simmered for an hour or so.   The 2nd skein was a dismal tan color, so I added a glug of ammonia to the bath water and the color quickly changed to a rich golden shade.  Here are the results:

Alum mordant / left: 1st bath / right: 2nd bath (plus ammonia)

Tansy ragwort - Mordant Sample Card