Research

The Keeper of the Herbarium has had a long-standing interest in the species of Pelargonium, culminating in the publication of a book in 1996.

Miller, D. Pelargonium - a gardener's guide to the species and cultivars and hybrids, B T Batsford, London

The checking of the nomenclature of all the entries, and the collection of herbarium material from the RHS Trial of scented pelargoniums in 1996, raised questions about the origins of certain cultivars, such as ‘Fragrans’ which is presumed to be of hybrid origin.

The RHS has collaborated with University of Reading on a number of short projects to determine mitochondrial and plastid inheritance in Pelargonium. It is hoped that the results will enable further work to be carried out to try to ascertain the origin of the regal, scented-leaved and unique pelargoniums first raised in the nineteenth century, and still so popular with horticulturists today.

Hybrids of known parentage and their parents have been studied. The DNA was extracted from both mitochondria and chloroplasts and results from two initial small scale projects have shown that the inheritance in both cases was maternal.

The work has demonstrated that a system can be developed to trace the origin of hybrids involved in some scented-leaved pelargoniums. The project is now being extended and refined. Further deliberate reciprocal crosses between the species thought to be involved in the parentage of some of the scented-leaved cultivars and the original regal pelargoniums are being made for this study.

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