The hairless leaves of Pteronia fasciculata are sessile and opposite, clustered densely together near stem tips in four neatly arranged vertical columns. The leaves become 1,5 cm long and 3 mm wide. They have entire margins and fold in along their midribs to form a keel below. The lanceolate leaf-shape tapers to an acute tip that is sharp and hard.

Leaf colour in shades of green or yellow green varies with the temperature and moisture changes of winter and summer seasons. The upper leaf surfaces are usually a little sticky. A membranous base is visible where the leaf joins the stem. This membrane started off as a sheath over the leaf when it sprouted.

Leaves drop off the older stems, leaving the pale grey lower parts of the shrub bare (Vlok and Schutte-Vlok, 2010; iSpot; JSTOR).