Rhododendron Cultivars A

A. Gilbert

The A. Gilbert grex, raised by T. H. Lowinsky, is of the same parentage as ‘Lady Bessborough’, though a different form of R. campylocarpum was probably used. A.M. 1925.

'Addy Wery'

Corolla about 1 1⁄2 in. wide and long, of a rather hard shade of bronzy red, with deeper speckling in the upper part. Leaves glossy. Compact habit (Kurume azalea ‘Suetsumu’ × ‘Malvaticum’; H. den Ouden, Holland). A.M.T. May 5, 1950.

Rhododendron 'Addy Wery' in the Savill Garden, Windsor Great Park, UK. 10 May 2012. Image John Anderson.

Adelaide

The Adelaide grex is the result of a back-cross of R. thomsonii onto Aurora, made at Exbury. The plants show the influence of the species in the foliage and the large calyx, but the flowers are in larger trusses, and the corollas funnel-campanulate, about 3 1⁄2 in. wide, blood-red. A.M. 1935.

Rhododendron Adelaide in Ray Wood, Castle Howard, North Yorkshire, UK, 5 April 2026. Image John Grimshaw.

Rhododendron Adelaide at Exbury, Hampshire, UK. May 2010. Image John Anderson.

Close up on a truss of Rhododendron Adelaide at Exbury, Hampshire, UK. May 2010. Image John Anderson.

'Admiral Piet Hein'

This is of the same parentage as ‘Mrs A. T. de la Mare’ but has mauvish flowers without any pronounced marking in the throat, though the central lobe is lightly speckled. A.M.T. 1957.

Rhododendron 'Admiral Piet Hein' at Dunedin Botanic Gardens, New Zealand. 25 November 2023. Image Tom Christian.

Rhododendron 'Admiral Piet Hein' flowering at Frogmore, Windsor Great Park, UK. 10 May 2017.

A close up on a truss of Rhododendron 'Admiral Piet Hein' at Exbury, Hampshire, UK. 10 May 2017. Image John Anderson.

Rhododendron 'Admiral Piet Hein' at Exbury, Hampshire, UK. 12 May 2012. Image John Anderson.

Rhododendron 'Admiral Piet Hein' at Dunedin Botanic Gardens, New Zealand. 25 November 2023. Image Tom Christian.

'Adriaan Koster'

Deep pure yellow (Mollis; M. Koster and Sons, 1901). One of the few self-coloured yellows in the Mollis group, and probably the best.

'Aladdin' (auriculatum × griersonianum)

Flowers up to 14 in a loose truss; pedicels clad with white, glandular hairs. Corolla up to 4 1⁄2 in. wide, funnel-shaped with a slender base, salmon pink with a deeper coloured throat. Leaves oblong-elliptic, acute, narrowed to a slightly cordate base, thinly brown-hairy beneath. A large shrub, flowering late June or early July. (Crosfield. A.M. 1935.)

Rhododendron 'Aladdin' in the Valley Gardens, Windsor Great Park, UK. 5 June 2019. Image John Anderson.

Close up on a truss of Rhododendron 'Aladdin' in the Valley Gardens, Windsor Great Park, UK. 5 June 2019. Image John Anderson.

'Albatross'

White with a pink tinge on the reverse, wavy at the margin (Knap Hill, 1941). A.M.T. May 26, 1953.

Albatross (discolor × Loderi)

A beautiful group of hybrids resembling Loderi in their huge, fragrant, seven-lobed corollas varying in colour from almost white to delicate pink from deeper coloured buds, while the influence of R. discolor shows in their tall growth, in their later flowering (from end-May but mainly in June), and often in the pronounced green or maroon ray in the throat (see Rothschild Rhododendrons, pl. 58). The best known clones are ‘Exbury Albatross’ (F.C.C. 1935), flowers blush pink with a brownish ray in the throat; and ‘Townhill Albatross’, raised by Lord Swaythling, with flowers described as Fuchsia Pink at the edges, paler in the centre (A.M. 1945).

Rhododendron 'Exbury Albatross' at Exbury, Hampshire, UK. 6 June 2006. Image John Anderson.

'Album Elegans'

Truss compact, with about 16 flowers. Corolla at first tinged with mauve, opening white with a flare of greenish yellow, funnel-shaped, about 21⁄4 in. wide. Medium size, vigorous. Early June. An old hybrid of R. catawbiense. (Waterer, Knap Hill, before 1847.)

'Album Grandiflorum'

This is similar to ‘Album Elegans’, but the flowers are up to 3 in. wide, flatter, slightly frilled, with a brownish-green flare. An old hybrid of R. catawbiense.

'Alice'

Truss conical, with 14 to 18 flowers. Corolla broadly funnel-shaped, about 33⁄4 in. wide, rosy pink fading to blush at the centre of the lobes, unspotted. Calyx regular, with strap-shaped lobes to 1⁄2 in. long. Mid- to late May. (Waterer, Bagshot. A.M. 1910.) It is said to be a seedling of ‘Pink Pearl’, but is quite distinct in its unspotted flowers and is also rather laxer and more erect; also perhaps not quite so free-flowering. It is named after Mrs Gomer Waterer.

'Alice'

From the same raiser and of the same parentage as ‘Anny’, is similar, but the colour is indeterminate, the upper part of the corolla being crimson, shading to orange.

'Alice de Stuers'

Salmon-pink suffused with orange-pink; flare orange (Mollis; M. Koster and Sons).

'Alice Street'

More recently, M. Koster and Sons has put into commerce ‘Alice Street’, the result of a cross between ‘Diane’ and R. wardii. It is a fine hardy yellow, with large, bowl-shaped flowers, but is scarce in commerce.

Alison Johnstone (concatenans × yunnanense)

Flowers up to ten in a loose truss. Corolla funnel-shaped with a tubular base, yellow or greenish yellow at first, becoming apricot pink, about 11⁄2 in. wide at the mouth. In the form that received an Award of Merit in 1945 the corolla is unmarked, but in some plants there are two bands of speckles inside. April. (G. H. Johnstone, Trewithen.)

Rhododendron 'Alison Johnstone' in the Valley Gardens, Windsor Great Park, UK. 24 April 2022. Image John Anderson.

Rhododendron 'Alison Johnstone' in the Valley Gardens, Windsor Great Park, UK. 24 April 2022. Image John Anderson.

Rhododendron 'Alison Johnstone' (Ray Wood, Castle Howard, North Yorkshire, UK, April 2020). Image John Grimshaw.

'Alpine Glow' (calophytum × Loderi)

The clone ‘Alpine Glow’, with pink-flushed flowers, received an A.M. in 1938.

Rhododendron 'Alpine Glow' at Exbury, Hampshire, UK. 5 April 2008. Image John Anderson.

Close up on a truss of Rhododendron 'Alpine Glow' at Exbury, Hampshire, UK. 5 April 2008. Image John Anderson.

'Altaclarense'

This name belongs properly to a hybrid between R. molle (Azalea sinensis) and a late flowering form of R. viscosum, raised at Highclere and figured in Bot. Reg. (1842), t. 27. It had white flowers, flushed with pink at the edge, spotted with yellow on the upper lobe and with a tinge of yellow in the throat. It must have been similar to ‘Daviesii’ (q.v.), which has the same parentage. The azalea grown at the present time as ‘Altaclarense’ is quite different and evidently not of the same parentage. The flowers are soft yellow with a deeper flare, and with an orange-pink flush on the upper lobes which fades as the flower ages. It received a First Class Certificate in 1862, when shown by Lee of Hammersmith, and was said to be Azalea sinensis × Ghent azalea. An excellent azalea, giving good autumn colour. It does not fall into any established category, but in appearance and flowering time it is nearer to the Mollis azaleas than to the Ghents, with which it is grouped in the International Register.

‘Altaclarense’ is said to be the same as ‘Aurea Grandiflora’, of which the nurseryman William Young of Milford held the entire stock in 1859 (Gard. Chron. (1859), p. 891). The parentage of this was stated by Young to be Azalea sinensis × Azalea pontica (i.e., R. molle × R. luteum).

For ‘Altaclarense Sunbeam’ see ‘Sunbeam’. For azaleas deriving from ‘Altaclarense’ see ‘Mrs Oliver Slocock’ and ‘Christopher Wren’. Another, apparently not yet in commerce in Britain, is ‘Golden Flare’, raised in Holland and highly rated there.

Altaclerense (arboreum × (catawbiense seedling × ponticum))

This foundation-cross, from which many of the pink- and red-flowered hardy hybrids are derived, was made at Highclere, the seat of the Earl of Carnarvon, in 1826, by J.R. Gowen. The seed-parents were specially forced plants from a cross between R. ponticum and a selected seedling of R. catawbiense. The pollen came from a truss off the plant of R. arboreum at The Grange, Alresford, which had flowered for the first time in the previous year. 1800 seedlings were raised and the bulk distributed to private gardens and nurseries in England and Scotland. Of those retained at Highclere, one flowered in 1831, and was figured and described in the Botanical Register for that year (t. 1414).

Whether any of the plants originally distributed from Highclere still exist it is impossible to say. Having a hybrid as one parent, the plants must have varied, some inclining to Smithii, others to Russellianum (qq.v.).

Old plants of Rhododendron Altaclerense are often massive. Kilmacurragh, Wicklow, Ireland. 10 April 2011. Image John Anderson.

Flower trusses on Rhododendron Altaclerense at Kilmacurragh, Wicklow, Ireland. 10 April 2011. Image John Anderson.

Rhododendron Altaclerense flowering at Mount Usher, Wicklow, Ireland. 7 April 2013. Image John Anderson.

'Amber Rain'

Buttercup-yellow with an orange flare (Knap Hill – Exbury). A.M. May 19, 1958.

Amor (griersonianum × thayerianum)

Truss lax, with about ten flowers. Corolla funnel-campanulate, 2 1⁄2 to 3 in. wide, pale pink with a red throat, slightly speckled on the upper lobe. Leaves oblanceolate, acute, with a skin-like indumentum. June. (Stevenson, Tower Court. A.M. 1951.) A charming rhododendron of moderate size.

Rhododendron 'Amor' at Exbury, Hampshire, UK. 27 June 2007. Image John Anderson.

Rhododendron 'Amor' at Exbury, Hampshire, UK. 27 June 2007. Image John Anderson.

Angelo (discolor × griffithianum)

This cross was first made by J.C. Williams of Caerhays, who called it ‘Cornish Loderi’, R. discolor being closely related to R. fortunei, which, with R. griffithianum, is the parent of the Loderi grex. The cross was later made at Exbury by Lionel de Rothschild, and by A. G. Soames of Sheffield Park. Angelo resembles Loderi in its flowers, but they are borne later, at the end of May or early June, and usually have more pronounced markings in the throat. The plants grow taller, to about 25 ft. In the form which received the Award of Merit in 1935 when shown from Exbury, the flowers were described as 5 1⁄4 in. wide, wavy-edged, delicately tinged with pink, marked with reddish brown in the throat. Leaves 6 to 8 in. long, including the short, stout petiole (the last a discolor character). In ‘Exbury Angelo’ (F.C.C. 1947) the flowers are white, with green throat markings. In ‘Solent Queen’, another Exbury clone, the flowers are pale rose fading to white (A.M. 1939). ‘Sheffield Park Angelo’ has white flowers with greenish-yellow markings in the throat (A.M. 1950; R.C.Y.B. 1950, fig. 40). The Angelo clones are essentially plants for woodland gardens and need a sheltered, half-shaded position.

Rhododendron 'Angelo' at Exbury, Hampshire, UK. 19 June 2013. Image John Anderson.

Close up on a truss of Rhododendron 'Angelo' at Exbury, Hampshire, UK. 19 June 2013. Image John Anderson.

Close up on a truss of Rhododendron 'Solent Queen' in the Valley Gardens, Windsor Great Park, UK. 25 May 2017. Image John Anderson.

'Annabella'

Golden yellow flushed orange-rose (Knap Hill-Exbury, 1941).

'Anny'

Corolla orange-red, about 21⁄4 in. wide, faintly speckled. Calyx-lobes about 1⁄4 in. long, mostly obtuse, sometimes acute (R. kaempferi × ‘Malvaticum’; C.B. van Nes and Son, 1920).

'Apple Blossom'

Pure soft rose (Mollis; K. Wezelenburg and Son). Highly rated in the Boskoop Trials of 1966.

'April Glow'

Flowers seven to ten in the truss. Corolla campanulate, 11⁄2 to 13⁄4 in. wide, frilled, red in the bud, opening deep pink, somewhat darker on the reverse. Leaves oval, rounded at the base, up to 31⁄4 in. long, reddish when young. May. Low, dense habit (‘Wilgen’s Ruby × williamsianum; A. C. van Wilgen, Holland).

'Arborfield'

Using ‘Crest’ as one parent, T. H. Findlay has raised a number of fine hybrids for the Crown Estate Commissioners, Windsor, which are not yet generally available (1975). The following have received awards and been described in the Rhododendron and Camellia Year Book (the second parent is given in brackets): ‘Arborfield’ ([x] ‘Loderi Julie’), A.M. April 30, 1963, R.C.Y.B. 1964, p. 134 and fig. 54.

Rhododendron 'Arborfield' in the Valley Gardens, Windsor Great Park, UK. 24 April 2022. Image John Anderson.

'Arbutifolium'

Flowers about 12 in a racemose cluster; rachis about 1 in. long. Corolla rosy pink, slightly spotted, tubular-funnel-shaped, 11⁄8 in. wide, scaly outside, downy inside at the base. Style slightly downy in the lower part; stigma yellow. Calyx very small, the lobes being less than 1⁄8 in. long. and much shorter than the ovary, with a few hairs at the edge. Leaves 11⁄4 to 2 in. long, up to 7⁄8 in. wide, more or less elliptic, equally narrowed at both ends, leathery, dark dull green above, purplish in winter, covered beneath with brown scales among which are scattered larger, darker scales. A dense, dwarf shrub to about 4 ft high, more in width, flowering in June.

A hybrid of unknown history, usually considered to be R. ferrugineum × R. minus; it was in cultivation under its present name in 1833, but was first described by Rehder in 1904. It is useful for its late flowering and fairly common in collections.

Argosy

The Argosy grex is the result of crossing R. auriculatum with R. discolor, which, like R. diaprepes, is a member of the Fortunei subseries flowering late, but earlier than that species.

*Rhododendron 'Argosy' at Exbury, Hampshire, UK. 2 July 2014. Image John Anderson.

*Rhododendron 'Argosy' at Exbury, Hampshire, UK. 7 July 2006. Image John Anderson.

'Argosy Snow White'

The Argosy grex is the result of crossing R. auriculatum with R. discolor, which, like R. diaprepes, is a member of the Fortunei subseries flowering late, but earlier than that species. ‘Argosy Snow White’ received an A.M. in 1938 when shown by Messrs Waterer of Bagshot. It flowers in July and has shorter leaves than Polar Bear. The cross was originally made and named at Exbury.

'Armistice Day'

Truss rounded with 10 to 14 flowers. Corolla shaped more or less as in ‘Britannia’, crimson-scarlet, about 3 in. wide. Calyx with narrow lobes. Leaves lanceolate, about 6 by 21⁄4 in. Lax habit. May. (Van Nes.)

'Arthur Bedford'

Truss compact, with 14–16 flowers. Corolla funnel-shaped, 31⁄4 in. wide, lavender with a deep brownish-red flare. Leaves oblong-elliptic, to 61⁄2 in. long, with purplish petioles. Tall, fairly compact, vigorous. Late May or early June. (Lowinsky, before 1935, distributed from Exbury. F.C.C.T. 1958.) Arthur Bedford was for some years head gardener to Lionel de Rothschild at Exbury.

Rhododendron 'Arthur Bedford' in the Valley Gardens, Windsor Great Park, UK. 26 May 2020. Image John Anderson.

Arthur J. Ivens (houlstonii × williamsianum)

Flowers about five in the truss. Corolla widely campanulate, up to 3 1⁄4 in. wide, deep rose in the bud, opening Persian Rose with two small crimson marks at the base. Filaments of stamens white. Style glandular throughout. Leaves oblong-ovate, to 2 3⁄4 in. long, 1 1⁄2 in. wide. Low-growing and compact, wider than high. (A.J. Ivens, for Messrs Hillier; cross made 1932. A.M. 1944.) Arthur Ivens was for many years nursery manager to Messrs Hillier.

Close up on a truss of Rhododendron 'Arthur J Ivens' in the Valley Gardens, Windsor Great Park, UK. 11 April 2017. Image John Anderson.

Rhododendron 'Arthur J Ivens' in the Valley Gardens, Windsor Great Park, UK. 11 April 2017. Image John Anderson.

'Arthur Osborn'

Flowers about six in the truss; pedicels clad with white, glandular hairs. Corolla funnel-shaped, about 21⁄2 in. wide, dark red. Leaves oblong-lanceolate, to 31⁄2 in. long, with a fawn indumentum beneath. Open, dwarf habit. June. (griersonianum × sanguineum subsp. didymum; Royal Botanic Gardens, Kew.) One of the best late-flowering rhododendrons for a small garden. The name is given as clonal only in the International Register, but the cross was made in other gardens. A clone of the same parentage is ‘Nutmeg’.

'Asa-Gasumi'

Flowers solitary or in pairs. Corolla 11⁄4 in. wide, Neyron Rose, scarcely spotted. Calyx petaloid, large, misshapen (Kurume; Wilson No. 14).

'Ascot Brilliant'

Flowers 10 to 16 in the truss. Corolla funnel-campanulate, about 2 in. wide, bright crimson red, with black speckling on the upper lobes. Calyx-lobes up to 1⁄4 in. long, often tinged with red. Leaves elliptic, to about 4 1⁄2 in. long, slightly glaucous beneath. Medium size, rather lax habit. Late April or early May. (Standish, before 1862.) A hybrid of R. thomsonii crossed with some hardy hybrid, and probably the first ever to have been raised from that species. It is very free-flowering.

Rhododendron 'Ascot Brilliant' in the Valley Gardens, Windsor Great Park, UK. 17 April 2019. Image John Anderson.

Close up on a truss of Rhododendron 'Ascot Brilliant' in the Valley Gardens, Windsor Great Park, UK. 17 April 2019. Image John Anderson.

'Atalanta'

Corolla 21⁄4 in. wide, near Mallow Purple, but duller than in ‘Pippa’ (q.v.). Slight coarse, dark speckling on the upper lobe. Style and stamens white. Low growing (R. kaempferi × ‘Malvaticum’; C. B. van Nes). Inferior to ‘Pippa’.

Augfast (augustinii × fastigiatum)

The Augfast grex (augustinii × fastigiatum) is related to Blue Tit, but the flowers are darker in colour and borne somewhat later. It is also taller-growing. The cross was made by E. J. P. Magor, who named it, later by Messrs Hillier and Messrs Reuthe.

Aurora (Kewense × thomsonii)

Aurora (Kewense × thomsonii). – Flowers eight to ten in a broad, lax truss. Corolla funnel-shaped with a narrow tube, 5– or 6-lobed, 33⁄4 in. wide, rosy pink (Neyron Rose), with slight speckling in the throat, nectaries crimson. Calyx 3⁄4 in. wide. Leaves intermediate between those of the parents. A tall, very vigorous shrub. April. Raised by Richard Gill in his nursery at Tremough, Cornwall, but named by Lionel de Rothschild. A.M. 1922. It is so similar to the best forms of Luscombei that it has even been suggested that Gill used R. fortunei, not Kewense, in making this cross (Rhodo. Soc. Notes, Vol. III, p. 188). The cross was later re-made at Bodnant.

The Brinco grex (Loderi × thomsonii) is virtually the same as Aurora, but no plant of any note has emerged from it.

The Adelaide grex is the result of a back-cross of R. thomsonii onto Aurora, made at Exbury. The plants show the influence of the species in the foliage and the large calyx, but the flowers are in larger trusses, and the corollas funnel-campanulate, about 31⁄2 in. wide, blood-red. A.M. 1935.

'Avalanche'

Raised by Isaac Davies of Ormskirk, Lancs, from R. molle (Azalea sinensis) crossed with R. viscosum. With pure white flowers.

Avalanche (calophytum × Loderi)

Flowers fragrant 12 to 14 in the truss; pedicels rosy red. Corolla funnel-shaped, 4 in. wide, 6– or 7-lobed, pure white with three lines of speckles in the throat uniting into a blotch at the very base. Tall-growing, to some 20 ft. Early April. Rothschild. The description is of clone ‘Avalanche’ (A.M. 1934; F.C.C. 1938). In other forms of the cross the flowers are delicate pink (Rothschild Rhododendrons, pl. 18). The clone ‘Alpine Glow’, with pink-flushed flowers, received an A.M. in 1938.

Rhododendron 'Avalanche' at Achamore Garden, Gigha, UK, showing the lines of speckles described in the text. 29 April 2024. Image Tom Christian.

Close up on a truss of a Rhododendron labelled 'Avalanche' in the Valley Gardens, Windsor Great Park, UK, but perhaps another form of the cross aas the flowers lack the speckles. 6 April 2020. Image John Anderson.

Another Rhododendron 'Avalanche', this time at Exbury, Hampshire, UK, different again from the other plants illustrated here. 4 April 2011. Image John Anderson.

Rhododendron 'Avalanche' at Exbury, Hampshire, UK. 25 April 2013. Image John Anderson.

Azaleoides

The name R. azaleoides starts in a French work – Dumont de Courset’s Botaniste Cultivateur, Vol. III (1811). The plant described had come from England, and there is little doubt that it was the hybrid raised at Thomson’s nursery at Mile End, near London, from R. ponticum pollinated by some azalea – possibly R. periclymenoides (nudiflorum). It is figured in Andrews’ Botanical Repository, t. 379 (1804), under the name R. ponticum var. deciduum, though R. azaleoides was apparently the name used for the hybrid by the nursery. At any rate, Sims stated in 1822 that Thomson had four varieties under the name R. azaleoides, one of which had scented flowers. This name has been a source of confusion, since it was used more or less in the same sense as the modern term ‘azaleodendron’ and applied later to other hybrids of this character. The azaleodendron described in previous editions of this work under the name R. azaleoides is most probably a hybrid between R. viscosum and R. maximum and, as Rehder pointed out, does not resemble the Thomson plant figured by Andrews. Whether the original R. azaleoides is still in cultivation it is impossible to say.

Azor (discolor × griersonianum)

Flowers about eight in a lax truss. Corolla trumpet-shaped, 7-lobed, about 3 in. wide, pink, speckled on the upper lobe, deep red in the throat. Style glandular-hairy in the lower part; stigma red. Leaves dull green, oblong-elliptic or oblanceolate, 7 in. long, 2 in. wide. Tall-growing. June. The cross was made originally at Tower Court, but later repeated in other gardens. The plant described here is a good average member of the grex, but some plants have bluish-pink flowers. The best clone is ‘Azor Sister’, from Tower Court (F.C.C.T. 1960).

Rhododendron 'Azor' resplendent in the Valley Gardens, Windsor Great Park, UK. 9 June 2018. Image John Anderson.

Superb trusses on Rhododendron 'Azor' in the Valley Gardens, Windsor Great Park, UK. 9 June 2018. Image John Anderson.

'Azuma-Kagami'

Corolla 11⁄2 in. wide, pale carmine rose (52d), paling in the throat, with faint speckling. Style and most of stamens malformed, some of the latter slightly petaloid. Calyx large, petaloid, coloured like the corolla. Dense habit (Kurume; Wilson No. 16). There is another azalea in cultivation as ‘Azuma-Kagami’, which is similar to the plant described but has a more deeply lobed corolla, some of the lobes being almost free. It is also of more open, twiggier habit. The plant described is very hardy and free-flowering.