Assuming a nice board with straight grain (no runout) was to be turned into a 1:3 [] stringer - taller than it is wide - designed to resist vertical bending, would it be stiffer with the grain running horizontally [=] or vertically[||] when viewed from the end of the stringer?

I've looked online, but it's a bit of a hard question to put to a search engine!

My guess is that there's probably not a lot of difference as the tension and compression forces are 'along' the grain regardless?

Simeon.