This widespread southeastern diploid (2n = 18) usually grows on seasonally damp acid soils, especially in thin woods and brushy old fields. It is locally abundant in southern and western regions of Ky., but virtually unknown in northeastern regions. A disjunct site was recently reported in southeastern Ohio (Gardner et al. 2004). D. scoparium has been treated as related to the more the northern tetraploid (2n = 36), clandestinum. These two species occur in somewhat similar habitats, although scoparium tends to occur on poorer soils and in more open habitats with more summer drying. However, recent analysis of DNA suggests that scoparium (with its southern ally, D. scabriusculum) has a more basal position in the phylogeny of North American Dichanthelium, sister to the angustifolium complex (Majure et al. 2023). D. scoparium differs from clandestrinum (FNA 25, W) in its denser velvety (versus hispid) pubescence, with distinctly bearded nodes (versus glabrous or sparsely hairy) and a "constricted, glabrous, viscid ring" [1-2 mm wide] below each node; and inflorescence branches are "often mottled with purplish, viscid spots". Leaf blades tend to be narrower: mostly 9-20 mm (versus 15-30 mm), with larger ones at least ca. 13 mm (versus 20 mm); sheath summits are "purplish, with yellowish spots" (versus "mottled with pale spots"). Also, spikelets tend to be more elongated: 2.2-2.8 x 1.3-1.5 mm (versus 2.4-3.6 x 1.2-1.5 mm); ligules are of hairs 0.5-2 mm lpng (versus membraneous, 0.4-0.9 mm long). Without complete colls. scoparium can also be confused with robust plants of acuminatum or oligosanthes.