Early this year I notice that my Hydrangea tree foliage forming a small clump and not growing fully. It’s like they haven’t matured. I’ve studied the internet…looking for a virus or insect issue…maybe a photo of the same. I know I’ve seen this before in a plant…it just escapes me. So I’m putting it out to my fellow Master Gardners. Do you recognize the problem here? I thought at first it was a mite…then I investigated the possibility of herbicide damage…and I’ve looked into virus like Hydrangea Chlorotic Mottle; although I don’t see curling on the leaves or yellowing at all. Could there be a deficiency? OK my friends and fellow Master Gardners…I need help with this one and am sure one or more of you know the answer. I need to know my next more…do I dig it up or can I save it?
Monroe County Master Gardener Association 
Could be plant fasciation (an unusual growth on a portion of a plant) IF not caused by a herbicide. Recommendation is to remove the growth. Very interesting article by MSU: http://msue.anr.msu.edu/news/plants_with_abnormal_growths_the_interesting_phenomenon_of_plant_fasciation
Article is very interesting.
my knock out roses grew like this all summer. weird.
My hydrangea has the same issue! I’m looking to identify the issue as well so I know how to treat it.
Possibly herbicide damage or aster yellow disease? I have same problem and I’m not sure, yet, of the cause.