Grassy lawn weeds can be challenging to identify, especially once mown, as that can change their growth habit and remove key characteristics needed for ID. We're not certain which species this is, though our initial impression based on traits we think we can see is Bermudagrass. We can share a couple resources that might be able to narrow-down the potential species that you can use to inspect the plants for the defining features. It sounds like a summer annual, being in active growth in summer and dead in winter (unless it's just winter-dormant), which helps because only some of the typical lawn weeds are annuals. (Crabgrass being the primary one in that group.)

• Weed Identification Photos
• Ohio State -- Weedy Grass Identification
  This resource includes a photo guide to the structures involved in grass ID, and has a short key to sorting-out common species based on those traits. Although this is an Ohio publication, it still is useful for Maryland lawn weeds.

Management recommendations will depend on what species this is, but in general, summer annuals can be spot-treated or just kept mown so they don't go to seed before dying this autumn. Seed germination can be prevented next year with either a pre-emergent herbicide and/or improving the density and vigor of the lawn so it can out-compete most weeds on its own in the future.

Perennial grassy weeds will need either physical removal to dig out the roots, or spot-treatment with systemic herbicide (potentially more than once) in order to kill the entire plant, roots and all. Bermudagrass will require this treatment as it is hard to eradicate, so you might want to dig it out first, then spot-treat with herbicide what reappears. Glyphosate might be the only herbicide ingredient that will subdue Bermudagrass. The same lawn improvement efforts can then similarly keep any perennial grassy weeds from returning as a new generation of seedlings by helping the lawn to out-compete them.

Miri

Miri

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