On July 3, I put up a post about Windmill grass (Chloris verticilatta) and on August 2 a post on Bermudagrass (Cynodon dactylon). You will also find several posts on crabgrass (Digitaria spp) over the last two years.
Right now is early August, the seedheads from each of these species are visible in lawns. I thought it would be a good time to get some pictures of the three species to help with identification.
Here is the seedhead of Windmill grass. This warm-season grass has been moving into central Iowa and north for the past few years and there is quite a bit of it in Ames this yeas. It branches off in all directions and rolls like a tumble weed when it breaks lose from the stem. It is a little larger than most crabgrass seed heads.
Windmill grass forms a tight-knit mass of slolons in the lawn and at this time of year it is covered by seedheads. (See picture 2)
Here is bermudagrass. It also has a branching seedhead, but notice how each branch arises from the same point. It is quite rare in central Iowa, although it looks like it may be expanding in this region.
This is crabgrass. It is one of the most common weeds in Iowa. Unlike the other two which are perennials, this one is an annual and has to come back from seed each year. It is similar to bermudagrass, but notice how it branches off from varying areas along the stem.