Crassula perfoliata leaves

These Crassula perfoliata leaves may belong to var. coccinea given the colour, or to var. minor, given the shape. C. perfoliata var. coccinea has leaves channelled at the base. This makes these leaves more likely to belong to C. perfoliata var. minor, although they are not grey-green and the plant on which they grow rather large.

Only some of the variations in C. perfoliata, and the recognised varieties of it, display the feature of leaf bases surrounding the stem "by appearing to pass through the substance of the long-lived evergreen leaves". The feature is recognised in the specific epithet of perfoliata (per meaning through and folia being leaves).

Borderline cases either get lumped with others in the most likely category, or cause new categories to be created. The more categories, the more grey areas to ponder when considering individual differences. Thus the complexity of nature may be surpassed by the complexity of human classification systems (Smith, et al, 2017; iNaturalist; www.plantzafrica.com).