Monsonia crassicaulis showing two types of leaves

Some of the leaves on this Monsonia crassicaulis stem tip have long petioles or stalks, soon to be recognised as spines when their leaves drop off. The leaves of this plant are thus dimorphic (appearing in two forms): the "normal" ones on short stalks growing solitary or in whorls in the spine axils lower than the "elevated" spine tip leaves.

Note the irregular leaf margins, how the leaves fold in along their midribs and the colour changes of the spines as they age (Vlok and Schutte-Vlok, 2010; www.plantzafrica.com).