Hydrangea bretschneideri Dippel

This hefty shrub much resembles Hydrangea heteromalla, with its toothed, more or less sharply pointed leaves, matt dark green above,and white or cream flowers in flat corymbs ringed by well developed sterile flowers. At present there is no botanical consensus on whether it should be treated as a species in its own right, although it is distinct as an especially hardy garden plant. We include it briefly at species level to reflect the real uncertainties and incompletely understood variation patterns in this group, but to create an illusion of settled knowledge would serve nobody. The issue is discussed fully under H. heteromalla.

H. bretschneideri is found at the northeastern end of the heteromalla complex’s wild range, even approaching the Beijing area. It tends to be less tall than H. heteromalla s.s. and H. xanthoneura, rarely exceeding 3 m and never assuming tree form. It proves hardier than typical H. heteromalla in colder gardens, has bark which is chestnut brown and peeling by the second year, and while the leaf undersurface may have some white hairs, especially at first and on the veins, it does not have the velvety, white indumentum of H. heteromalla s.s.. Unlike H. xanthoneura, its first year branchlets lack lenticels (Wei & Bartholomew 2001; Edwards & Marshall 2019; Haworth-Booth 1984; Bean 1981). While it is quite easy to point to ‘typical’ examples of each species, the dividing lines in truth seem rather hazy. Several varieties in the complex, most described by Alfred Rehder (1912 and in Sargent 1913) and now largely ignored, shifted confusingly between species and have not always been sunk into the species in which they were first described (Royal Botanic Gardens, Kew 2021).

It was first described scientifically (as H. vestita var. pubescens) by Sargent (1890), Dippel (1893) raising it to species level. Sargent was working from plants grown at the Arnold Arboretum from seed collected by Emil Bretschneider, a medic and all-round sinologist working for Imperial Russia, from mountains near Beijing in the early 1880s. This introduction forms the basis of most garden stock, a group of similar clones (Bean 1981). More recent introductions include garden seed distributed by Shanghai Botanical Garden, taken from a 2006 wild collection in Gansu, as grown at Howick Hall, UK (Howick Hall Arboretum 2024). Between 1994 and 2010 NACPEC expeditions made numerous seed collections under NACPEC, BJG and QLG numbers, in the Beijing municipality, Shanxi and Shaanxi. Many of these are grown at the Arnold Arboretum, US National Arboretum and other collections in Eastern North America, with identifications wavering between H. bretschneideri and H. xanthoneura (US National Arboretum 2024; Arnold Arboretum 2024). The hardiness of this species is a great virtue here, as well as in northern and central Europe, where it has been grown since the early 20th Century at Gothenburg, Sweden (Gothenburg Botanical Garden 2024), and even in southern Finland (Arboretum Mustila 2024).

We list all cultivars belonging to H. heteromalla in the widest sense together under ‘Hydrangea heteromalla Species Complex Cultivars’.