The foliar trichomes of Plectranthus laxiflorus Benth [Lamiaceae]: an important medicinal plant

Plectranthus laxiflorus (family Lamiaceae), is an important medicinal plant, distributed east of the southern continental escarpment from Humansdorp in the Eastern Cape province of South Africa. The distribution and morphology of leaf trichomes of P. laxiflorus were investigated using a combination of light and scanning electron microscopy. The leaves of P. laxiflorus bear both glandular (peltate and capitate) and non-glandular trichomes which are distributed on both the adaxial and abaxial surfaces. Capitate types of trichomes were fewer and more sparsely distributed than the peltate type. Initiations of both glandular and non-glandular trichomes were observed at various stages of leaf development. However, the proportion of mature to immature trichomes increased with leaf maturity, with immature trichomes being exceedingly rare on fully mature leaves.