Grasses of the genus Sporobolus are relatively easily spotted in the field when in flower, having an inflorescence that is typically a long, narrow, cylindrical panicle (called a "rattail" in some species) crowded with simple, one-flowered spikelets (see photo at right). In the case of S. virginicus under ideal conditions, the inflorescence can be fairly thick (see Fig. 11C) rather than rattail-like; this native dune grass has been used for verge planting along Mokulele Highway on Maui and is the only Sporobolus in Hawai‘i that spreads by runners (rhizomes). The rest are clumping grasses and many are characterized by narrow (wiry) leaves. Many are difficult to distinguish (identify to species) unless examined closely under magnification.

Sporobolus diandrus starts out with the culm branches closely appressed to the axis (see Fig. 11A, at right) as in the other species, but the branches spread open as the flowers mature (see Fig. 11C, below; the same is somewhat true for S. pyramidatus). Sporobolus indicus, S. africanus, and S. fertilis are difficult to distinguish as characteristics of each tend to intergrade (Clayton & Snow, 2010). What we are calling, S. indicus, has become an exceedingly common ruderal species along roads in the Hawaiian Islands, particularly in dry to mesic environments. Sporobolus diandrus and, to a lesser extent, S. pyramidatus, are similarly common ruderals on calcarous soils.

The spikelet of a Sporobolus is simple, consisting of a single floret encased in four floral bracts: two glumes, a lemma, and a palea (see Fig. 11B). Glumes are distinguished as first or lower glume and second or upper glume. In some species, the glumes may not be obvious except on very close examination, being short, tattered, and closely adherent against the lemma or palea. When the grain is released, the glumes are left behind; or all the floral bracts remain attached to the pedicel and the bracts left gaping.