Prinsepia uniflora Batalin

In terms of phylogeny, Prinsepia uniflora is sister to P. sinensis; in horticultural terms, perhaps its ugly sister. Adapted to harsher conditions in the wild, in cultivation it forms, in Dirr’s words, ‘a rather thorny, moderately dense aggregate of light gray branches.’ Its darker, slenderer leaves are not as densely borne on the branches as those of P. sinensis, and its flowers are white rather than yellow. Dirr describes it as superior to P. sinensis in foliage colour, but the comparison is made in the context of a recommendation to plant it as a hedge or a barrier (Dirr 2009). Ernest Wilson damned it with faint praise, suggesting that ‘though not so fine as its yellow-flowered sister this is a good plant especially for rocky places’ (Wilson 1927).

The natural habitat of the species is centred around the loess plateau in north-central China, which is made of silt-like sediment formed by the accumulation of wind-blown dust. According to Ma et al. (2019), it likely had a more restricted distribution at the time ice sheets were at their greatest extent, about 20,000 years ago, when its range was slightly south of its current distribution. It is the most drought-tolerant of the Prinsepia species. While it is likely niche conservation contributed to the north-south divergence of Prinsepia, with P. sinensis and P. uniflora moving north and separating from P. utilis in the Himalayan region, local adaptation may have led to the subsequent speciation of P. sinensis and P. uniflora. Bioclimatic variables related to precipitation show significant differences between the sites where the two species are found. In addition, P. uniflora shows a high level of genetic diversity in wild populations, which may be the result of the broad west-to-east range of the species (Ma et al. 2019).

This shrub does well in any moderately fertile, well-drained soil in full sun or light shade, but requires a hot sunny site to fruit well (Stewart 2010). According to Bean (Bean 1976), at Kew it has grown freely, producing long, slender leaf shoots every year, but as it flowers early in the year, it tends to suffer from late frosts and rarely develops fruit. For Reginald Farrer (1916–1917), who collected the species in Gansu, the fruits have ornamental value (‘beautiful pendent oval berries of rich crimson on long pedicles’), though scant comestible merit, as they consist ‘of almost nothing but skin and stone.’ The fruits are nonetheless edible, with a pleasant sour taste, and are eaten raw or cooked (Fern 2025). The kernel, called ruiren in traditional Chinese medicine, has long been used for the treatment of eye diseases (Wang et al. 2021). A recent study has shown that an extract from the kernel can be used to protect against ultraviolet radiation and prevent skin ageing (Wang et al. 2022).

Prinsepia uniflora can be propagated from seed, though according to Dirr and Heuser (1987), germination rates are quite low (30%). Stratification in the range of one to two months gives the best results. Rooting from cuttings is also possible, though not easy. The success rate may be increased by removing the callus from the cutting and re-treating with rooting hormone. Cuttings can be taken in summer, but the wood should be firm.

It was introduced to Western cultivation in 1911 by William Purdom (1880–1921), who was sent to collect in China as part of a joint venture financed by the Arnold Arboretum and James Veitch & Sons, the British nursery. Purdom seems to have been a character as tough and thorny as the shrub he introduced. A head gardener’s son from the Lake District in northern England, he joined the Royal Botanic Gardens, Kew as a student gardener. He became secretary of the Kew Employees Union and in 1905 was dismissed for ‘agitation’. He petitioned the Board of Agriculture and was reinstated, leading to the resignation of the Garden’s director. Back at his post, Purdom organised the only strike that there has ever been at Kew. It is probable that Kew recommended him to Sargent, who was looking for someone to undertake a three-year expedition to China, because they welcomed the excuse to have him far from the institution. He wasn’t tough only with his employers. When in 1912 he and his party were ambushed on the banks of the Yellow River by armed bandits who shot two of their horses, Purdom drew a lever-action rifle and, as he’d later report, ‘made a stand’, shooting three of the attackers and several of their horses. He collected P. uniflora in 1910, near Yan’an in the Shaanbei region of Shaanxi province (Royal Botanic Gardens, Kew | Data Portal 2025). The species was introduced at the Arnold Arboretum, where a plant was raised from Purdom’s seed in 1911, flowering for the first time in 1914 and producing fruit the following year (Rehder 1915). A few years later, material was sent from there to Kew, where it likely was better received than its strike-organising collector would have been (Gordon 2021).

The epithet uniflora means ‘single flowered’, in reference to the often single flowers, less common in Rosaceae than multi-flowered clusters. The species, in fact, bears flowers one to three together, but Batalin’s protologue mentions flores solitarii in foliorum fasciculis (‘solitary flowers borne in clusters of leaves’) (Batalin 1892).