Pin oak leaves tend to be smallest of the three, Scarlet a tad bigger, and Red the biggest.

For many years pin oak grows like a conifer, with a pointed top and many level branches, with those lower down longer than those higher up. It and scarlet oak produce deeply lobed leaves, but scarlet oak does not have the distinctive habit of pin oak. Red oak produces much more shallowly and less frequently lobed leaves, and a very broad tree with a small number of widely spaced, long, heavy branches.

Yardworker 1, I have all 3 in my yard, and I agree, it's tricky by leaf shape. The PIn oak tree, is pretty easy to spot if you go by the trees growing form. I have the red oak (Rubra) and the (Coccinea) Scarlet. I can pick out my Rubras VS my Shumard and Nuttalli's. I have 1 baby Scarlet oak. But by leaf shape it is difficult. My Rubras have a different shape now in their "teen years". If I had to choose between the PIN, SCARLET, OR RED. For a fast growing beautiful tree, in a yard with limited room, I would HAVE to say Pin Oak. Which NEEDS a PH of Neutral 7.0, or lower. The red oak Q. Rubra should be a 2nd choice for a large yard where you could plant 2 oak trees. I Just have actually spent some time under my Pin oak today. I saw it's nice form and I was in awe. I just was so happy i planted it, it is so wonderful. Yes, I am not joking. But I think that the Q. Nuttalli is a nice oak also. I really don't have an oak that I think isn't wonderful, really. I will add that the REd Oak is likely to grow to be more Massive than any of the other oaks mentioned. Unless you try a Compton's oak, that is,. The Compton's oak has no real fall color. It is in the "White oak family" anyways. Not like the Pin Scarlet or Red oaks. Well, all 3 of the oaks "Pin, Scarlet and Red" oaks are said to have red fall color. All 3 may be red in your area yardworker. I can remember the "pin oak" in my yard actually 2 of them, being a quite showy red leafed tree in fall. There are Scarlet and Rubra in my area. I will have to pester the neighbor with a Q. Rubra on what he remembers in fall from his giant Rubra which I planted in !997. I really don't recall how good the fall color is.

Thanks for all the great responses. I'll go take another look at this tree and see if I can better ID it now.

Is it true that Pin Oak is unique in hanging on half the leaves in winter before dropping off in spring.

Yes tiger, both of mine do that. I do have a bunch of Pin oak acorns this year. I have a cart parked under my younger pin oak, and there are lots of acorns that dropped right into the cart. I was surprised, they were ripe and I didn't see them last years when they were green, but on the tree nonetheless. If you are interested, my neighbor has a Q. Rubra tree with acorns now also. I can send you a handful of each. He said all his oaks have acorns this year, I had planted those oaks several years ago, but they may be green, so just the Pin oak and N. Red oak are ready to my knowledge. Let me know if you want a few of each.