Dr Chris Thorogood, Deputy Director at Oxford Botanic Garden and Arboretum, is co-author of a new study exploring the taxonomy of Cistanche tubulosa, a parasitic plant (sometimes known as a ‘desert hyacinth’) found in deserts and traded for herbal medicine and used since antiquity.
The study, which Dr Thorogood co-authored with Dr Majed Aldughayman and Professor Julie Hawkins of the University of Reading, was published in Phytotaxa, the world’s largest journal in botanical taxonomy. The authors show that the species name Cistanche tubulosa has been applied to plants that in fact comprise a polyphyletic group, meaning they are not all derived from a common ancestor. Moreover the type specimen for C. tubulosa is missing. A type is a plant specimen to which the scientific name of that plant is formally associated; it serves to anchor the defining features of a particular taxonomic group. When a type specimen is lost or destroyed, botanists may designate a new specimen, or neotype, to serve in its place to maintain nomenclatural stability. To resolve the taxonomic confusion surrounding C. tubulosa, the authors have assigned a new type (or neotype) for the species, using a specimen collected from South Sinai in 1945.
Cistanche tubulosa belongs to the genus Cistanche, a genus that is taxonomically complex, in which species limits are poorly understood. Like related genera (broomrapes for example), they are difficult to distinguish in the field and they preserve poorly in herbaria. The genus Cistanche has a long history of use as a food and in herbal medicine in semi-arid and arid regions, and many species of the genus are rare or of conservation concern. In Traditional Chinese Medicine, Cistanche are known as Rou Cong-Rong and used for a variety of ailments and as a health or ‘tonic’ food.
It is hoped that the neotypification of C. tubulosa will help stabilise the understanding of the species and resolve taxonomic confusion, which will in turn direct conservation efforts.
