oak with odd looking acorns (SOLVED: overcup oak)

[Lanier_Lurker]

I happened upon this oak during a lunchtime walkabout at work the other day.  I did not have my camera with me so I had to stuff some acorns and leaves into my pocket.

These are the largest and weirdest looking acorns I have ever seen.  They are right at 1 inch in length, but well over 1 inch in diameter.

Also, the cap completely encloses the nut.  Some of the caps had begun to peel away as you can see.

Lastly, this rather small ornamental tree (less than 10" caliper) had dropped a huge crop of these acorns.  I could have easily filled a 5 gallon bucket (and then some) with what had already fallen, and many were still on the tree.

I've looked around on the Internet and have found some possible matches.  I think this may be some sort of hybrid - perhaps a Sargent Oak (Quercus x sargenti (robur x prinus).

http://www.nuttrees.com/hybrid.htm

[ely]

maybe an overcup oak. not sure thats the real name though. i seen it in a book once.

[woodtroll]

It does kind of look like overcup, but it is not. The acorns are to big and the cup to thin. I would bet on Sargent Oak and also would bet that overcup is part of the cross. The leaves are similar but not right for overcup. I wounder what it is crossed with.

[SwampDonkey]

I vote overcup Q. lyrata as well. My book says up to 1" in length and wider in width. Also says can be almost fully covered by the cup. Leaf pictured in my book looks the same, odd shaped and not very symmetrical.

[SwampDonkey]

Sargent oak is a cross between English oak and chestnut oak (robur x prinus), I looked it up is the only way I knew.

[okie]

Here, in the river bottoms, there are many many oaks that shed acorns like that. The trees arent little though, they are the largest oak trees in this area...and also the largest oak trees I ever seen in girth and height combined. One in the nearest bottom is a good 5 foot through and 60 to 75 feet up to the first real branch, I've seen larger across the river though. I never knew what species they were, most hillbillies around here call em water oaks on account of that is where theyre found.

[SamB]

Overcup oak, not  common in my area.......pictures in my book match LL's pics......discription of where it likes to grow matches Okie's......I vote for Overcup

[Dodgy Loner]

Overcup oak.  It's a very common ornamental because, like many other river bottom species, it does quite well in the compacted clay soils of North Georgia cities.  It's probably the most common oak on the UGA campus, although it very rarely occurs this far north naturally.

[woodtroll]

Overcup I worked with had a 1 inch acorn but a thicker cap. very hard to peel open. The trees do get large. The Burr Oak also have caps that can surround most of the acorn but the caps are thicker yet.  In the swamps the acorns can be very big (size of a ping pong ball), on the plains and up north they are alot smaller. Both species of tree get big... but the burr can be significantly bigger.
I still vote with LL .

[Lanier_Lurker]

Looks like it is probably overcup oak.

I wonder if it is an improved cultivar like this one endorsed by Dr. Dirr?

http://www.marshalltrees.com/upload/pdf_trees/88_file.pdf

[SwampDonkey]

Local bur oak has small acorns, but I read that they are a fair bit bigger than what we have. Depends on site. I'm only used to immature trees here that I found on an abandoned farm. Most are further south around Grand Lake. Up here most decent land that is flat and well drained is a field so a lot of marginal species for this far north have been nearly wiped out. Not that the species are endangered or anything, just that they are disappearing from NB.