I read in SpinOff Spring 1983 about a variety of flax plant good for fibre called Cascade, developed in Oregon, and I discovered this pdf from Oregon State University extension.oregonstate.edu/catalog/pdf/em/em8952-e.pdf that discusses flax.
Page 6 states, "Many excellent fiber flax varieties were developed in Oregon in the mid-1900s, but modern European fiber flax varieties have much higher fiber content (approximately 30 percent vs. 15 percent). They are also more disease- and lodging-resistant than early varieties."
I'm curious to know what these varieties are called and where to get seeds. Not that I want to plant and harvest any, but just for curiosity's sake.