The leaves of Lacomucinaea lineatum caused the reclassification into its own, monotypic (one species only) genus called Lacomucinaea.

The leaf-shape is called fusiform, meaning a spindle-shape, wide in the middle and tapering at both ends. The leaves are also succulent and terete, i.e. cylindrical.

The leaves become detached from the stem easily. The feature by which leaves are shed early is referred to in botany as caducous. In this species the leaves start ageing from the petiole side, not the leaf-tip.

The petioles of L. lineatum leaves leave a persistent stub when they fall off (Lacomucinaea, a new monotypic genus in Thesiaceae (Santalales) by Nickrent and Garcia, 2015, Researchgate; Vlok and Schutte-Vlok, 2010).