From what I've read, and seen, conifers put on lignin rich wood on the bottom side of vertical branches. Compression wood. Hard woods put on cellulose rich wood on the upper side of vertical branches. Tension wood. I have made Osage bows from from the topside of branches and it is stronger wood no doubt.
I think you mean horizontal branches?
That's why I posted my link which shows an almost vertical branch with weird heart wood/sapwood.
I think the simplistic illustrations we often see in books are pretty poor and have often just been coppied endlessly without question.
E.G:- we've all seen the pic of the horizontal branch, where it tells you to use the upper face. Yeah?
... But in reality (with Yew), it's the upper face where the branches all sprout up from! So if you want to avoid knots, the lower face will be the clean one, and that will have the coarser rings and the compression wood. So what do you do? You look for a vertical branch like I did, and what do you find? The wood is still all weird... so much for simple theory.
Bottom line is, you don't know what it will look like inside until you cut it, and don't believe everything you read in the books.
Del
(Don't trust cats either!)