Platostoma rotundifolium is a species of jellywort native to much of sub-Saharan Africa.
This species is a perennial herb or small shrub growing tall. It arises from a horizontal woody rhizome and is not known to be aromatic. The stems are erect, square in cross-section, and branch mainly in the upper parts. They are covered with short hairs, which may point upwards or backwards, and scattered small surface glands.
The leaves are stalked and often bend downwards. The leaf blades are ovate to oblong, measuring long and wide. They have serrated to scalloped margins that are often slightly rolled under, with blunt tips and bases that are heart-shaped or wedge-shaped. The leaves are hairy to densely hairy and bear scattered surface glands; the upper leaves are frequently white, pink, or purplish in colour. The leaf stalks are short, about long.
The inflorescence is dense, with many-flowered whorls packed closely together so that they touch. The upper bracts are green and upright, forming a small terminal tuft, while the lower bracts are white, pink, or purple, spreading or bending downwards and becoming leaf-like. The flower stalks are slightly flattened and long.
The calyx is very small, only long at flowering, and densely hairy with surface glands. It enlarges to in fruit. The throat is partly closed by the shape of the calyx lobes. The corolla is white or purple, long, with a short tube. The stamens protrude slightly beyond the corolla, up to .
The ovary is smooth. The fruits consist of dark brown, obovoid nutlets about long, with fine longitudinal ridges and usually smooth surfaces, though young nutlets may bear small hairs.
Platostoma rotundifolium is widespread in tropical Africa, where it grows in grassland (especially where prone to flooding), alongside streams, and in other marshy places. It has been recorded in Angola, Benin, Burundi, Cameroon, the Republic of the Congo, the Democratic Republic of the Congo, Eswatini, Ethiopia, Guinea, Ivory Coast, Kenya, Malawi, Mozambique, Nigeria, Rwanda, Sierra Leone, South Africa, South Sudan, Tanzania, Uganda, and Zambia.