Wednesday, September 15, 2010

Chewed Oak Leaves

When I first saw these leaves, I thought they had been hard hit by some herbivorous insects. Closer examination made me think the leaves may have been distorted by some infection or weather related phenomenon. The margins of the leaf appear to be healthy. Could the leaves have been eaten at an early developmental stage and then healed as they matured?

The leaves belong to a small oak on the edge of one of the prairie openings. Not all of the leaves are like those above, but I couldn’t find a single leaf on the tree that hadn’t been damaged in some way. Being on the edge of two different habitat types increases the range of insect species that might come into contact with and find edible, this little oak.

Some leaf clusters suffered just minor damage. This tree bears all of the indicators of being Quercus bushii, a hybrid between the Blackjack Oak, Quercus marilandica and the Black Oak, Quercus velutina. Perhaps, instead of hybrid vigor, this individual received enhanced taste as a result of the cross.

The feeding pattern on this leaf makes me more certain that the damage to the first leaf was indeed feeding damage. Until a better theory comes along, I’m going to say that the feeding was done on young leaves and the leaves partially healed as they grew.

I wish I could have seen this tree early in the year, but it’s impossible for me to get around and see everything in all seasons. I’ve noticed that the majority of things I notice while I’m walking are within ten feet of me. I’ve walked through this particular prairie opening many times this year, but if I was more than ten feet from the tree, I probably wouldn’t have noticed anything peculiar about the leaf shape. This is another one of those things that I’ll put on my list to watch out for next year. Maybe I’ll find the answer then.


  1. Hi Steve ..It does appear to be damage from insects but early on enough so it has been able to repair itself but caused a stunting of the leafs !!
    There again who am I to know!! : }
    I know this spring that late season freeze damaged
    the large oak trees here!! The new leaves where just unfurling when they froze and those turned brown and sure looked funny until more where sent forth!!
    Steve I know you must be busy, but I would like your take on my last post about the pond!!

  2. grammie g - Freeze damage could produce the same effect. If other trees had shown the same thing, I might have gone with frost as my first choice of cause.