The hairs themselves are quite interesting, and seemingly have either a central channel or (as I think) they are folded around to form a kind of spiked tube, sort of like a blade of grass.
The five-sided folicular organ at the base of the hairs and the structure of the hairs where they emerge from the folicle is also fascinating (pics in link below.)
If you section the hip tissue, you will find the innermost tissue layer growing hairs and supporting achene development is heavily laden with calcium oxalate crystals. Meanwhile, if you can get the achene sectioned, you will find CaOx of completely different morphology proliferating in the endosperm.
Hip hairs and follicles images:
https://www.yogile.com/u1j8gkd04yl#51m
Hip and achene sections:
https://www.yogile.com/kqfz89msx60#21m
I'd like to know what the hairs are made of. A friend who has studied them a long time says they are a silicate material, but he can't find the reference. I suspect it's more like gypsum. Anybody know?
Leonard