Germination response of four South African medicinal plants to a range of temperatures and treatments

Observation trials on seed germination of medicinal plant species of South Africa sometimes indicated erratic or low germination percentages (0-20%) attributed to seed dormancy. The aim of this research was to give a first report on the temperatures and treatments needed to obtain a high percentage of seed germination for four indigenous medicinal plant species, Alepidea amatymbica, Bowiea volubilis subsp. volubilis, Dicoma anomala subsp. anomala, and Leonotis ocymifolia var. raineriana. Germination, including additional treatments, like smoke treatment and removal of hair like structures on seeds, were investigated at temperatures ranging from 10°C to 30°C. Smoke treated seeds of A. amatymbica germinated best (10%) at 25°C while D. anomala showed increased germination (68%) at 15°C after the removal of hair like structures. Germination of untreated seeds of L. ocymifolia was best at 20°C with a germination percentage of 78%. Untreated seeds of B. volubilis germinated at 15°C gave the highest germination percentage of 92%.