Near solid stuff will be sold as rattan.
Bike frames aren't very tightly controlled. In something like flyrods, enormously tight controls for stiffness are used. Even with those heat treating is sorta at the marginal end of the spectrum of distinctions. So with the kind of construction where tolerances aren't even being held to the 1/10" heat treating isn't something you should loose a lot of sleep over. On the other hand it can make the grass a nice dark colour.