The upper leaves of Silene undulata subsp. undulata are spaced in opposite pairs upon the stems. They are stalkless or sessile, more or less broadest where they join the stems. The leaf hairiness is visible in the photo, some of the hairs being glandular, making the plant sticky. The narrowly lance-shaped leaves taper to acutely pointed tips and curve variably. Leaf colour is dull green to slightly blue-green.

A bud and withered flower are visible in picture. The sepals are fused in a long calyx tube without bracts at the base, enclosing the petal bases. The calyx tube is more prominently longitudinally lined in the old flower than the bud (Manning, 2007; Vlok and Schutte-Vlok, 2010; Bond and Goldblatt, 1984; iNaturalist).