The Truth of the Uruk-hai

[Galin]

You are free to hold that interpretation of course (and I'll bet you're not alone), but what Treebeard might see and what he knows are yet two different things.

'Treebeard is a character in my story, not me; and though he has a great memory and some earthy wisdom, he is not one of the Wise, and there is quite a lot he does not know or understand.' JRRT, Letters

Now that doesn't mean I toss aside everything Treebeard says. Indeed not! But the quote you are raising has the character himself essentially admitting that he does not know what Saruman has done. Saruman has been doing something, but what? 'I wonder what he has done? Are they Men he has ruined, or has he blended the races of Orcs and Men?'

Good questions, but questions nonetheless. Have 'half-orcs' been seen? If so the beings under question are maybe something like what Merry describes: 'horrible: man-high but with goblin-faces, sallow, leering, squint-eyed' -- indeed the half-orcs as Aragorn calls them.

And if it was the Uruk-hai that were noted, again, how would Treebeard know (not that he would claim to know), why it was they didn't seem to mind the Sun? Big Orcs who don't appear to mind the Sun or man-high Orc-faced beings doing damage to the forest could easily be 'all the same' to an Ent... close enough in any case, with respect to Entish concerns, though it probably would make one wonder what Saruman has done.