A pungent odor wafts across the flower-filled summer meadow. The smell is coming from the abundant yellow daisy-like flowers that are scattered everywhere. This is hayfield tarweed, or Hemizonia congesta. They look pretty, with three-lobed ray flowers encircling a soft yellow center. But if you pick one up you’ll get a sticky souvenir: this plant is incredibly resinous, and the smell and the stickiness will follow you until you can scrub off. Low-slung dogs will come back from hikes needing a bath, and the fragrance (strong but not unpleasant) lingers on fur and clothes.
Hayfield tarweed can be either white or yellow, and there are a number of other species of tarweed as well (though they are in several different genuses, and vary a fair amount in the way they look). The seeds of the Hemizonia and Madia tarweeds are edible–they were among the many types of seeds that Native American tribes collected and ground into flour. One miner described watching the Sierra Miwoks harvest in 1851: “During the months of August and September we often saw Indians coming and going. It was the time of their harvest; they came to our flats to gather all kinds of seeds, even hayseeds. It is the Indian woman who does this work; she has a big hamper or very open basket, of very fine reeds, and coated with a starch made of powdered seeds and warm water. She holds this hamper with one hand under the grass in seed; then with a sort of fan also made of reed… she pulls the grass over her hamper; the seeds, thanks to the shake given by the fan, are detached and fall.” (excerpt from California Grasslands, edited by Stromberg et al)