It has leaves with a short ligule (<13 millimetres (33⁄64 in)), and panicles that are compact to open, rarely having secondary branching.

The inflorescence structure are large spikelets, 7.7–12.3 millimetres (39⁄128–31⁄64 in) long and 2.3–3.5 millimetres (23⁄256–35⁄256 in) wide, with strong awns (up to 20 centimetres (8 in) long), usually red.

O. barthii grows in deep water, seasonally flooded land, stagnant water, and slowly flowing water or pools; it prefers clay or black cotton soils (vertisol), and is found in open habitats.

[6] It is the progenitor of cultivated Oryza glaberrima, African rice.

[7][8] It has nodal roots hosting nitrogen fixing, photosynthetic strains of Bradyrhizobium.