Distyliopsis Endress

The genus Distyliopsis was described by Peter Endress in 1970 to fit a group of trees from the rainforests of southern China, Malaysia and New Guinea which had previously been classified in Sycopsis (or occasionally in Distylium). The name is a portmanteau of these two and the genus differs from Sycopsis in the absence of true sepals and from Distylium in the presence of a floral cup (like a tiny vase holding the bunch of stamens); out of flower, another point of distinction is that the buds of Distyliopsis are enclosed by bud-scales whereas those of both Distylium and Sycopsis are naked. In overall appearance the leaves of Distyliopsis species are very like those of Distylium (and of many other evergreens from these same forests), but they tend to show the conspicuously sunken side-veins of Sycopsis and are often narrowly obovate in shape, with a broadly rounded rather than a pointed tip (Zhang, Zhang & Endress 2003).

This tropical and subtropical genus need not concern most temperate gardeners, and it only gains mention in Trees and Shrubs Online because the name Distyliopsis tutcheri continues to surface in both European and North American horticulture (more often than not as the archaic Sycopsis tutcheri, and frequently enough even for the vernacular ‘Tutcher’s False-holly’ to have been proposed). Photographs of plants sold or grown under these names consistently show the sharply-pointed and more or less flat leaves characteristic of Distylium species; these plants often survive in places which might seem too cold to suit Distyliopsis tutcheri, a tree endemic to subtropical forests below 1000 metres in Fujian, Guangdong and Hainan provinces towards the far south of China (Zhang, Zhang & Endress 2003). It has been suggested that one such tree at the Iturraran Botanic Garden in northern Spain, obtained from the Mark Bulk nursery in Belgium, might be Distyliopsis dunnii instead (F. Garin pers. comm): D. dunnii does at least resemble Distylium racemosum more closely in leaf-shape, while its wide and largely tropical natural distribution extends to slightly higher altitudes and latitudes in China, suggesting that plants from these provenances could be somewhat hardier (Zhang, Zhang & Endress 2003). But there is no paper trail to hint at this tree’s introduction to northern Europe.

It seems probable that all of the stock offered in the west as Distyliopsis or Sycopsis tutcheri derives ultimately from a single plant at the Royal Botanic Gardens, Kew, England, which had been labelled as Sycopsis tutcheri in the mid 20^th century but which was later identified as Distylium aff. racemosum (Bean 1981; De Langhe 2014); the persistence within the nursery trade of the archaic mid-20^th century name (Sycopsis tutcheri) may itself offer a clue to these plants’ origin. It should perhaps however be borne in mind that this group of closely related genera are proving highly liable to interbreed when they are grown together: × Sycoparrotia (Sycopsis × Parrotia) has become the most familiar of these intergeneric hybrids in the west, but crosses between Distylium and Parrotia are also known. Both these are hybrids between very different looking plants – one evergreen, one deciduous – making them easy to spot. Were a cross between Distylium and Sycopsis also to have arisen, descendents would be much harder to identify; it is quite conceivable that such hybrids could be naively misidentified as some kind of Distyliopsis. The ‘Distyliopsis’ grown at Iturraran has winter buds rather like those of Sycopsis, without well-developed protective scales, and its flowers have a rudimentary floral cup (F. Garin pers. comm.); these features might be interpreted to suggest a hybrid of Distylium with Sycopsis, but genetic analysis would needed to prove or disprove such a hypothesis.