Identifying the plant material in the quillwork

When Heather Richardson, Jeremy Uden and Kate Jackson were cleaning and stabilizing the shirts for travel to Alberta, they noticed that not all the quillwork was actually quillwork. On two shirts, plant fibre was used in the same way as porcupine quills. This was photographed under magnification, but we were not able to identify the plant used. A review of published literature on Blackfoot use of plants, and emails to Blackfoot quillworkers, also didn't solve this puzzle. So, we took it to Alberta with us.