Notice the stem: it appears that a number of stems which are fused. It's called fasciation. It happens

That said, the curling & distortion of the leaves might be herbicide damage, even though inadvertent. Any chance of that?

This post was edited by jean001a on Thu, Aug 15, 13 at 0:12

Very interesting, I hadn't heard of fascination before. Thank you for the information.

As for herbicides, none are used on my property, though there is a large public park on the other side of the wall visible in the photo, they may use them.

I've attached a picture of the second odd looking sunflower, this one has the same kind of lumpy growths at the first, just more of them.

Okay, have changed my mind. Think that damage is due to herbicide. I've never seen such "tumors" with fasciation, but I have seen something similar with 2,4-D, a broadleaf herbicide. Then, too, public and large commercial agencies have access to products not sold to home gardeners.

Make certain you don't have a garden "helper" -- one who wasn't really much help. (sigh)

You might poll your neighbors to learn if they have strange growth in some of their plants. If so, document with images.

Suggest you run these images past your County's Extension Service office. The agent should be able to provide a definitive response.

Locate your county's office w/ this interactive map.
http://www.csrees.usda.gov/Extension/

Let us know what you learn.

Here is a link that might be useful: locate your county's Extension Service office

This post was edited by jean001a on Thu, Aug 15, 13 at 23:45

Sometimes mites do that sort of damage. I have seen similar looking growth on aloes, for instance.

Thanks for the follow up! I have emailed the San Bernardino Extension office, hopefully they'll get back expediently.

I have asked both neighbors and one does use herbicide to kill the ivy the city grows as a natural screen on top of the cinderblock wall between our houses and the public park. He wouldn't tell me what exactly he used or if he sprayed recently but upon looking up 2,4-D injuries, the leaves of both sunflowers look very much like them.

I've attached a picture taken from my backyard looking at the the neighbor's wall with the ivy killed via herbicide. The mutated sunflowers are behind the normal looking one seen.

I have also been checking for mites, as of yet, I haven't seen any on the leaves or stems. I'm not ruling it out, as I've noticed Argentine ants quite busily running all over the sunflowers since they sprouted back in May/June.

Hopefully someone from the Extension Office gets back soon with some definitive answers. I shall post all updates here.

Thanks- I'm curious.

Haven't heard back from anyone; just pruned everybody up today and decided to excise one of the tumors on a pruned leaf. Was surprised to see it looked like, well, a tumor.