Buddleja × wardii Marquand

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Credits

Andrew Large (2021)

Recommended citation
Large, A.T. (2021), 'Buddleja × wardii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/buddleja/buddleja-x-wardii/). Accessed 2022-08-11.

Genus

Glossary

Tibet
Traditional English name for the formerly independent state known to its people as Bod now the Tibet (Xizang) Autonomous Region of the People’s Republic of China. The name Xizang is used in lists of Chinese provinces.
Xizang
See Tibet.
apex
(pl. apices) Tip. apical At the apex.
axillary
Situated in an axil.
corolla
The inner whorl of the perianth. Composed of free or united petals often showy.
flush
Coordinated growth of leaves or flowers. Such new growth is often a different colour to mature foliage.
herbarium
A collection of preserved plant specimens; also the building in which such specimens are housed.
hybrid
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
indumentum
A covering of hairs or scales.
morphology
The visible form of an organism.
perfect
(botanical) All parts present and functional. Usually referring to both androecium and gynoecium of a flower.
phenology
The seasonal timing of events in the life cycle of a plant or animal and the study thereof.

Credits

Andrew Large (2021)

Recommended citation
Large, A.T. (2021), 'Buddleja × wardii' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/buddleja/buddleja-x-wardii/). Accessed 2022-08-11.

Putative in situ hybrids of Buddleja alternifolia and B. crispa. Shrub 1.5–4.5 m tall and spreading. Branchlets stellate-tomentose, glabrescent. Leaves opposite, sub-opposite or alternate, often all three on the same plant; leaf surface tomentose to glabreascent, elliptic or nearly so, 5–22 × 3–17 mm, apex acute, base cuneate ornearly so, margin entire or toothed. Inflorescence, terminal on main axis and on lateral branchlets, congested nearly as in B. alternifolia. Flowers intermediate between species; calyx 2 mm long, exterior stellate-tomentose; corolla pale lilac with an orange throat, corolla tube 6–7 mm long, 1–1.5 mm diameter; ovary subglobose, stellate-tomentose; stamens at or below middle of corolla tube. Capsules and seeds not seen. (Leeuwenberg 1979).

Distribution  China Xixang (Tibet)

Habitat In mountains and along riverbanks, 3000–3500 m asl.

USDA Hardiness Zone 5-9

RHS Hardiness Rating H6

Conservation status Not evaluated (NE)

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).


'Longstock Gem'

RHS Hardiness Rating: H5

USDA Hardiness Zone: 7-9

A hybrid of garden origin, selected in 1998 by Peter Moore (Longstock Nursery, Hampshire, UK) from a cross of B. crispa (agathosoma type) × B. alternifolia. A shrub with mostly oppsoite leaves, dark-green to grey-green in colour, and an arching habit. The infloresences are axiallary and terminal on the arching branches and borne on the previous season’s wood; it can start flowering slightly earlier in the spring than either parent species. The flowers are violety-lilac and intermediate (Moore 2020). Overall, the shrub closely resembles the hybrid (identified as B. × wardii) described above, except with respect to phenology.


'Longstock Silver'

Synonyms / alternative names
Buddleja 'Autumn Surprise'

RHS Hardiness Rating: H5

USDA Hardiness Zone: 7-9

A hybrid raised also raised by Peter Moore in the early 2000s from a cross of B. alternifolia ‘Argentea’ × B. crispa, ‘Longstock Silver’ is a large and vigorous deciduous shrub notable for its intensely silvered leaves, and is recommmend principally as a foliage plant as it can be shy to flower. The flowers, if they appear, are more or less the same as other hybrids of this type, but are borne on new growth in the autumn (Moore 2020).