Plants from the arid or sub-tropical zones of the Southern Hemisphere tend to grow quickly and die young in Ireland. The South African shrub, Psoralea pinnata, pictured below in 1934 at Mount Stewart is a typical example. Perhaps this plant went into decline after this photograph was taken, but by 1936, Lady Londonderry was sourcing new seed.
In a letter dated 13 May 1936 from the National Botanic Gardens in Cape Town, South Africa, Director R. H. Compton wrote, ‘I have much pleasure in sending seeds of Psoralea pinnata herewith … It was interesting to hear how well this charming shrub grows in Northern Ireland.’ – Edith Marchioness of Londonderry, “Mount Stewart Gardens 1935,” (1935).
Seed really is the best way to propagate this plant and one of our South African visitors earlier this year, Mike Kleyn, very kindly offered to obtain seed of this shrub for Mount Stewart from South Africa. A phytosanitary certificate was obtained and the seed sent. We now have a fresh crop of seedlings and in about two or three years time, this wonderful, fragrant plant will be back in the formal gardens at Mount Stewart.
As well as growing this plant as a multi-stemmed shrub, I wonder whether it might make a fine standard for the Italian Garden Parterres. We have so many seedlings we could spare a few to find out.
There are 130 species of Psoralea found mainly in the Southern Hemisphere with a few from the Northern. The ‘P’ is silent so it is pronounced ‘Soralea’. The generic name is derived from the Greek, psoraleos, which means warty or scurfy with reference to the raised glands on the bark and leaves which emit a strongly scented volatile oil. Another near hardy species would have been grown at Mount Stewart as it was collected by Harold Comber in 1926, whom Lady Londonderry sponsored. The young shoots of the Peruvian species glanulosa, is whisked up with water and sugar and used as a refreshing drink, ‘culen’.
Psoralea pinnata was introduced to cultivation in the British Isles in 1690 when it was collected from the Cape. Known as umHlonishwa in Zulu and Fountain bush in South Africa and in Afrikaans, fonteinbos, bloukeur and penwortel. The species is distinguished by its seed pod, which contains a single seed only. The plant likes water courses in South Africa, which may well explain its tolerance of our Northern Irish climate.
In South Africa, Psoralea pinnata flowers from October to December, so very likely, it will flower around June/July for us here. The flowers are blue/lilac and are themselves scented.