Leaf and stem anatomy of honeybush tea (Cyclopia species, Fabaceae)

The leaf and stem microstructure of commercialised Cyclopia species (Cyclopia intermedia, Cyclopia subternata, Cyclopia maculata, Cyclopia genistoides) is described and illustrated for the first time. Leaflet characters of diagnostic value include the shape, margin (flat or revolute), bundle sheath extensions, crystals (aggregates, solitary crystals and crystal sand), relative size of the upper and lower epidermal cells and thickness of the cuticle. The study revealed an abundance of phenolic compounds, not only in the leaf epidermal cells and leaf bundle sheaths, but also in the secondary phloem, xylem rays, xylem parenchyma and pith, showing that the inclusion of older stems may be acceptable and does not necessarily lower the quality of the product.

► The leaf and stem microstructure is described and illustrated. ► Leaflet characters are of diagnostic value at species level. ► The source species of commercial tea samples can be identified. ► Oxidised phenolic products are present in secondary phloem and xylem. ► Older stems may be acceptable for inclusion in honeybush tea.