This observation should be paired for comparison with the one that follows. The first photo shows a grass that I have been calling M. vimineum. The second shows it beside another, taller, grass with longer leaves mottled with white, which is farther advanced in development. A botanist who saw https://www.inaturalist.org/observations/180129449 of a grass very like the one with white-mottled leaves suggested the latter may be Leersia virginica.

In the subject of this observation, nodes are hairy. Leaves are slightly rough on both sides.

Agonizing re-appraisal: the grass in this observation is probably not M. vinimeum. For one thing, it has a visible seedhead on Aug 25. For another, it was rooted in one spot. For another, it has hairy nodes. Could it be a variant of L. virginica? Further "research" by me is needed.

First step is to compare and contrast what the botanist said (based on photos) might be L virginica with a specimen of M. vimineum that no one could cast doubt on. The next two observations do that.

No hair on nodes, no seeds seen . . . leaves smoother than those of "unknown number 1," the immediately prior observation
Three places where stolons were rooted
On Sept 12 I posted an observation to show the inflorescence of this species
https://www.inaturalist.org/observations/183002180