Two samples of fresh leaves (250 g each) of R. officinalis were
collected from same location within the University of Fort Hare,
Alice campus in the Eastern Cape Province of South Africa (latitudes
3000–3415S and longitudes 2245–3015E). The species
was collected in January 2009 and a voucher specimen (Okoh/09)
was deposited at the University herbarium. The plant was identified
by Prof. Don Grierson of the Botany Department, University
of Fort Hare, Alice.