Cornus × transamericana
Sponsor
Kindly sponsored by
Hugh and Judy Johnson
Credits
Martin Deasy, Dan Crowley, Jack Aldridge & Răzvan Chişu (2026)
Recommended citation
Deasy, M., Crowley, D., Aldridge, J. & Chişu, R. (2026), 'Cornus × transamericana' from the website Trees and Shrubs Online (treesandshrubsonline.
Synonyms
- Cornus × transamericanus J.Aldridge & S.Andrews, orth. var.
Infraspecifics
Other taxa in genus
- Cornus alba
- Cornus alternifolia
- Cornus amomum
- Cornus × arnoldiana
- Cornus asperifolia
- Cornus bretschneideri
- Cornus californica
- Cornus canadensis
- Cornus capitata
- Cornus chinensis
- Cornus controversa
- Cornus coreana
- Cornus darvasica
- Cornus disciflora
- Cornus drummondii
- Cornus × dunbarii
- Cornus elliptica
- Cornus × elwinortonii
- Cornus excelsa
- Cornus eydeana
- Cornus florida
- Cornus florida Cultivars A-G
- Cornus florida Cultivars H-M
- Cornus florida Cultivars N-R
- Cornus florida Cultivars S-Z
- Cornus foemina
- Cornus glabrata
- Cornus × haddenii
- Cornus hemsleyi
- Cornus hongkongensis
- Cornus hongkongensis hybrids
- Cornus × horseyi
- Cornus iberica
- Cornus kousa
- Cornus kousa Cultivars A-D
- Cornus kousa Cultivars E-I
- Cornus kousa Cultivars J-L
- Cornus kousa Cultivars M-R
- Cornus kousa Cultivars S-Z
- Cornus macrophylla
- Cornus mas
- Cornus mas Cultivars A-G
- Cornus mas Cultivars H-M
- Cornus mas Cultivars N-R
- Cornus mas Cultivars S-Z
- Cornus 'Mountain Moon'
- Cornus multinervosa
- Cornus nuttallii
- Cornus obliqua
- Cornus oblonga
- Cornus officinalis
- Cornus poliophylla
- Cornus 'Pumila'
- Cornus quinquenervis
- Cornus racemosa
- Cornus rugosa
- Cornus × rutgersensis
- Cornus sanguinea
- Cornus scabrida
- Cornus sericea
- Cornus sessilis
- Cornus × slavinii
- Cornus suecica
- Cornus sunhangii
- Cornus unalaschkensis
- Cornus walteri
- Cornus wardiana
- Cornus wilsoniana
Small deciduous tree to 8 m, with descending branches, looking most like Cornus nuttallii in general appearance. Inflorescences show intermediate characteristics between both parent species: typically four-bracted (as for C. florida, whereas C. nuttallii is usually six-bracted) with occasional additional bracts; opening pale yellow, turning white. Bracts large, obovate; each overlapping (not overlapping in either parent species); notched at outer tips (as for C. florida). Flower buds partially enclosed by bracts in winter, (fully enclosed for C. florida or exposed for C. nuttallii). Leaves deciduous, turning bright red-pink or orange in autumn (as for C. florida; autumn colour rarely produced by true C. nuttallii in Britain). Fruit rarely produced. Flowering mid-May to early June, before leaves emerge. (Aldridge & Andrews 2024).
Strikingly beautiful when seen at its best, the Pacific coast species Cornus nuttallii has always been found difficult to please in cultivation – slow to establish, shy-flowering and short-lived. Occasional examples that have proved easier to grow as garden plants have almost invariably turned out to be hybrids with the closely related C. florida from the other side of the United States (Bean 1976; Andrews 1991). Such hybrids have recently been given the name Cornus × transamericana (Aldridge & Andrews 2024). In overall appearance, they are often just as effective as Cornus nuttallii, with similarly large inflorescences (up to 15 cm across) borne on the bare branches in late spring, but the individual bracts tend to be noticeably more obovate and overlapping in their arrangement.
In terms of the hybrid diagnosis, the four-bracted inflorescences (in true Cornus nuttallii six bracts is the norm) and the recurved bracts with notched apices both point to C. florida as the other parent, as does the rich autumn colour in shades of bright orange, red or pink (C. nuttallii seldom colours well in cultivation) (Bean 1976; Andrews 1991). Unlike true C. nuttallii, though, the hybrid is not known to have a sporadic second flowering in autumn, and the trees do not set fruit. As well as being easier to cultivate than C. nuttallii, forms of C. × transamericana tend to be much longer-lived as garden plants, making them an effective alternative where the Pacific coast species is unlikely to thrive (Aldridge 2024); in many situations they also represent an improvement on straight C. florida, which has always been found difficult to cultivate outside its native range.
It is not known where or when the hybrid first originated – almost certainly in cultivation, since the geographic ranges of the parent species are not known to overlap. The cross has been deliberately made by a number of breeders, most famously the Canadian nurseryman Henry M. Eddie in 1945 (see ‘Eddie’s White Wonder’), who wished to combine the most desirable characteristics of both species to create a plant with large inflorescences and excellent autumn colour. However, examples of ‘C. nuttallii’ of confirmed hybrid origin are found in a number of European gardens, some of which clearly pre-date Eddie’s cross. The oldest such hybrid identified at the Royal Botanic Gardens, Kew was received from the Chenault nursery, Orléans, France as long ago as 1925 (Andrews 1991), while Dortmund Botanic Garden, Germany grows two hybrid accessions originally received as C. nuttalli from separate sources: one of these came from Hillier Nurseries in Winchester, UK, while the other was raised on a German nursery from seed obtained from the Arnold Arboretum, Massachusetts (Krüssmann 1984).
'Ascona'
Synonyms / alternative names
Cornus nuttallii 'Ascona'
Similar to ‘Ormonde’ in many respects, this is the name given to a clone widely distributed through the Dutch nursery trade as Cornus nuttallii, the cultivar name bestowed at a later date by H. J. Grootendorst, Boskoop (Andrews 1991). Of uncertain origin, it is still often erroneously listed as a cultivar of C. nuttallii, despite its clear hybrid characteristics (Aldridge 2024).
'Cobhay Titan'
Selected from a batch of seedlings raised from ‘Pink Blush’ at Junkers Nursery, Somerset, UK. This cultivar shows a greater influence from the Cornus nuttallii parent with larger inflorescences, often with additional bracts and good orange autumn colour (Junker 2023).
'Dorothy'
Bracts ivory white, opening with an attractive pale pink flush (not unlike ‘Pink Blush’), closer to Cornus florida in general appearance than most other cultivars. Selected and introduced by Buchholz Nursery, Oregon as part of their Flora Wonder™ Collection (Buchholz Nursery 2026). ‘Dorothy’ has shown the best red autumn colour of the C. × transamericana cultivars grown by Karan Junker (Somerset, UK), who introduced it to Britain from scions sent by Talon Buchholz (Junker’s Nursery 2022; K. Junker pers. comm. 2024).
'Eddie's White Wonder'
Probably the best-known Cornus × transamericana cultivar grown on either side of the Atlantic (Aldridge 2024), ‘Eddie’s White Wonder’ is the product of a deliberate cross made in 1945 by nurseryman Henry M. Eddie in British Columbia, Canada, in the quest for a plant with large, very white inflorescences and excellent autumn colour. The plant was the only survivor from a batch of hybrid seed to survive a 1948 flood that devastated the nursery – the promising seedling had fortunately been planted elsewhere.
Initially distributed on a small scale by by Eddie’s Nursery, the clone was patented and introduced in North America by Wayside Gardens in 1962. The patented cultivar is described as ‘generally erect and somewhat tall and pyramidal’, with an upright trunk and horizontal branches ‘slightly pendent at their outer extremities’, attaining 3.5 m height × 1.5 m spread after ten years; the pollen parent is given as C. florida ‘Rubra’ (PP 02413 P).
Three young plants were sent to the Valley Gardens, Windsor Great Park, in 1963 (Clarke 1988). Cappiello and Shadow (2005) note that two different clones seem have been been distributed under this name, a form circulating in Europe with a less spreading, more upright habit (Cappiello & Shadow). A seedling from the original cross is said to have been still growing in the Eddie family garden in Vancouver in 1992 (Straley 1992).
'Ormonde'
Awards
AM 1981
A rounded small tree with an elegant spreading habit, descending branches sweeping the ground. This clone was propagated from a celebrated ‘Cornus nuttallii’ specimen of unknown origin that used to grow near to the Main (Elizabeth) Gate at the Royal Botanic Gardens, Kew. Under that name, it was given an RHS Award of Merit in October 1981 for its bright red autumn colour, but its true identity was questioned. It was subsequently identified as a hybrid by Keith Ferguson, and given the cultivar name ‘Ormonde’ referring to the former hunting lodge (demolished 1772) that had stood in the Old Deer Park at Richmond (Bond 1984). The cultivar has had a small distribution in the United Kingdom and is represented by specimens in several larger gardens, including an excellent example in the Pinetum at RHS Garden Wisley (Aldridge 2024).
'Pink Blush'
Bracts white on opening, becoming increasingly flushed with pink. The colour further deepens with maturity, but only when grown in good light. This cultivar originated as a seedling from Cornus nuttallii at Handy Nursery, Oregon. The pink flush to the bracts suggests that a red-bracted C. florida selection known to have grown nearby might have been the other parent (Cappiello & Shadow 2005; Aldridge 2024) – compare with ‘Eddie’s White Wonder’. This is Karan Junker’s favourite of the C. × transamericana hybrids, forming an upright small tree with a neat, symmetrical habit and good autumn colour (Junker 2023). The success of this cross indicates the great potential for using newer selections of C. florida Red-Bracted Group to create a truly pink-bracted hybrid.
