Commelina lukei Faden (Commelinaceae) is newly described from southeastern Kenya, also distributed in northeastern Tanzania and Madagascar. It is distinguished from C. kotschyi Hasskarl by its larger, less undulate-margined leaves, larger spathes, and different distribution and ecology; from C. imberbis Ehrenberg ex Hasskarl and C. mascarenica C. B. Clarke by its capsule shape, appendaged seeds, and consistently clasping leaf bases; and from all three species by the presence of solely acicular hairs on the adaxial lamina midrib. Commelina milne-redheadii Faden is newly described from Zambia, also in Angola and Democratic Republic of the Congo. It differs from C. scaposa C. B. Clarke by the presence of leaves on the flowering shoots and larger spathes; from C. hockii De Wildeman by its narrower leaves and much smaller, striped spathes; from C. welwitschii C. B. Clarke by its tuberous roots, fewer-veined spathes, and several- to many-flowered upper cincinnus; and from all three species by its blue flowers and seeds with a dorsal ridge.