Carex pensylvanica, common oak sedge, is an important species in dry mesic and dry woodlands and is a main fuel species. It is clump forming, spreads by rhizomes, and grows about 8 in. tall. Sedges are extremely important for ants. According to Flora of Chicago (Wilhem & Rericha), many ant species nest in their root zones and some disperse their seed. The amount of Carex pensylvanica in an area has been correlated with the diversity and density of native ant species. The dense root zone has consistent soil moisture, meaning stable soil temperature, which is important for ants.
Formica subsericea is a larger ant, making it capable of carrying seed around. The seed has an elaiosome, a nutritious fatty appendage, that is eaten by the ant, and in return, the plant gets its seed moved around. This is called myrmecochory! This ant is identified by its pubescence (hairs), silky sheen, and the shape of its petiole (the part that attaches thorax to abdomen).