I am also having same question. Please tell me if this is a bermuda seedhead or some other.

Regards

From the picture it does looks like your grass is pretty high and needs to be cut down quite a bit.

Per Texas A&M- "1-2 inches for common, 1/2-1 1/2 inches for hybrid"

Seed heads usually form when your grass is under stress. So follow the Bermuda Bible and cut, water, and fertilize properly and they should go away.

There is common bermuda mixed in with your hybrid bermudagrass. Do what ChaoticUT said and mow lower and more often.

Both those lawns are too tall. Agree with the above.

I've bought a new reel mower and lowered cut height to 1-3/4". Have also reduced watering. I can now see lots of irregular brown patches (see pics). Any chance this (brown patch) is being caused by grubs and also stressing the lawn resulting in the seed heads?

I am in Austin, TX and pics were taken today - May 21, 2014.

additional picture

Looks more like a lack of sunlight, first of all, and secondly a shortage of fertilizer and water. You would have to take out the trees and buildings to get that lawn up to a higher level. Have you considered St Augustine? That would be perfect in that area.

Grubs are predictable. When you see June bugs or Japanese beetles swarming your porch light in May or June, then you can expect to see some grubs. Your lawn can tolerate a certain amount of grub population. Whether you will have enough grubs to be a problem can also be predicted. About a month after you see the beetles on the porch lights, dig up a square foot of sod. If you find more than12 little grubs in that square foot, then you will likely notice grub damage later in July, Aug, or Sept. If you have fewer than 12 little grubs, then the chances of seeing any damage are small. So dig up a spot, but don't treat if you have fewer than a dozen little grubs. And by all means, dig up where you think the damage is occurring.

You have another problem. Is that a 2-trunk oak tree in your yard? Regardless of what it is, the trunk of the tree is buried too low under the soil level.

Could those spots be the stolons? A result of letting the grass grow so high and then cutting it down so low?

Keep a short mowing height and frequent and those spots on your lawn will turn green, you can't let that grass grow too tall in between cutting because it will do exactly that.