Buddleja × wardii Marquand

Buddleja × wardii was named for Frank Kingdon-Ward, who collected specimens of this Buddleja in the Tsang-Po valley, Xizang (Tibet) during his 1924–25 expedition (Marquand 1929). Described by Marquand (1930) as a species with affinity to B. alternifolia, subsequent revisions of the genus (Leeuwenberg 1979) regarded the extant herbarium specimens as perfect intermediates between B. alternifolia and B. crispa, and classified B. × wardii as a hybrid.

It is not certain whether B. × wardii has been cultivated beyond China. However, there is a hybrid Buddleja of unknown origin commonly available in the UK, often erroneously labelled B. caryopteridifolia, which corresponds to the botanical descriptions of B. × wardii, and is hereafter tentatively identified as such. In addition, several garden hybrids of B. alternifolia and B. crispa are reasonably well known, and can be logically considered under B. × wardii. It is worth noting the garden hybrids are similar to the tentatively idenified B. × wardii specimen, and especially so with respect to flower morphology.

B. × wardii can grow into a large, scrubby shrub with arching branches. The new branchlets are covered in a dense white indumentum. The deciduous foliage is scented like B. alternifolia and is intermediate between the parent species, with the upper surface ranging from glabrescent to persistently tomentose according to the type and conditions, and the lower surface tomentose. The leaves are usually much smaller towards the flowering apex of the stems. The flowers are also intermediate, and in both terminal and axillary thyrses. The corolla is lilac-violet, with a small reddish eye. The fragrant flowers may appear in the spring on last season’s growth, but the main flush is in the autumn, meaning the shrub can be spring pruned if required.

The presumed parents are spring to early-summer flowering; however, alteration of the flowering phenology is quite common in Buddleja hybrids, with several hybrids of B. crispa (for example Buddleja ‘Salmon Spheres’) being notable for flowering much later in the year than either parent species. Growing conditions are similar to other similar Buddleja, with B. × wardii preferring full sun and a well-drained site. The hybrid is more hardy than B crispa, and less prone to die in cold, wet winters (pers. obs.).

The current author believes B. × wardii KR 4881, available in the UK horticultural trade, is not this hybrid and corresponds to the descriptions of B. alternifolia of the tsetangensis type, a specimen of which was collected by Kingdon-Ward from the same location as B. × wardii (Marquand 1929).