The short-stalked leaves of Pachycarpus vexillaris grow opposite, well-spaced and ascending on the stems.

The leaf-shape is narrowly oblong to lanceolate with wedge-shaped base and pointed tip. The margins are entire, yellow-ridged and wavy. Both surfaces are sparsely hairy. Leaf dimensions are about 40 mm to 75 mm long and 6 mm to 25 mm wide.

The thick, cream-coloured midrib is prominent on the lower surface, the blade halves often folding in slightly along it. Lateral veins are visible, spaced and curving in (Leistner, (Ed.), 2000; JSTOR; iNaturalist).