Philadelphus: The Hybrids

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Article from Bean's Trees and Shrubs Hardy in the British Isles

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'Philadelphus: The Hybrids' from the website Trees and Shrubs Online ( Accessed 2024-06-16.


(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
Flower-bearing part of a plant; arrangement of flowers on the floral axis.
Narrowing gradually to a point.
Sharply pointed.
(pl. apices) Tip. apical At the apex.
Lying flat against an object.
Situated in an axil.
Reduced leaf often subtending flower or inflorescence.
Small branch or twig usually less than a year old.
(pl. calyces) Outer whorl of the perianth. Composed of several sepals.
With a long tail-like appendage.
Made up or consisting of two or more similar parts (e.g. a compound leaf is a leaf with several leaflets).
Branched determinate inflorescence with a flower at the end of each branch. cymose In the form of a cyme.
A form of inflorescence in which the terminal flower is the first to open preventing further extension of the inflorescence axis. (Cf. indeterminate.)
With an unbroken margin.
Coordinated growth of leaves or flowers. Such new growth is often a different colour to mature foliage.
Lacking hairs smooth. glabrescent Becoming hairless.
Plant originating from the cross-fertilisation of genetically distinct individuals (e.g. two species or two subspecies).
Flower-bearing part of a plant; arrangement of flowers on the floral axis.
Lance-shaped; broadest in middle tapering to point.
Loose or open.
Taxonomic account of a single genus or family.
Egg-shaped; broadest towards the stem.
A much-branched inflorescence. paniculate Having the form of a panicle.
(botanical) All parts present and functional. Usually referring to both androecium and gynoecium of a flower.
Petal-like. May refer to sepals or stamens modified into a petal-like form.
Unbranched inflorescence with flowers produced laterally usually with a pedicel. racemose In form of raceme.
(var.) Taxonomic rank (varietas) grouping variants of a species with relatively minor differentiation in a few characters but occurring as recognisable populations. Often loosely used for rare minor variants more usefully ranked as forms.


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Article from Bean's Trees and Shrubs Hardy in the British Isles

Recommended citation
'Philadelphus: The Hybrids' from the website Trees and Shrubs Online ( Accessed 2024-06-16.

In the 19th century various hybrids arose spontaneously in gardens between the species then in cultivation, notably the Old World P. coronarius and the American P. inodorus and P. pubescens. Some of these are treated with the species. The hybrids described below are of more recent origin and are mostly the result of deliberate crossing. Except where otherwise stated, they are the creations of the great French plant-breeder Victor Lemoine of Nancy (1823–1912) or of his successors, and it would be no exaggeration to say that these still represent three-quarters or more of the philadelphus hybrids grown in gardens, even though the newest of them are almost half a century old.

The history of the Lemoine hybrids goes back to 1883, the year in which Lemoine received from the USA a plant of P. microphyllus. Crossing this with garden varieties of P. coronarius he obtained ‘Lemoinei’ (1888), ‘Erectus’ (1892), ‘Avalanche’ (1896), and ‘Manteau d’Hermine’ (1898). These are the best known members of the Lemoinei group (P. × lemoinei Rehd.), characterised by the rather small, very fragrant flowers and by the small, smooth, sparsely toothed or almost entire leaves. The later hybrids are of more complex ancestry. Those with double flowers arranged in a determinate raceme and with hairy calyces are thought to be crosses between ‘Lemoinei’ or its allies and the double form of P. × nivalis (see p. 138). The best known of these is ‘Virginal’ (1909), which is the type of P. × virginalis Rehd. Other hybrids in this group are ‘Girandole’, ‘Argentine’, and ‘Enchantement’.

In many of the Lemoine hybrids the inflorescence is a cyme or a reduced panicle, suggesting that P. inodorus or P. insignis enters into their parentage. Those which also have a glabrous calyx have been classified by Rehder as P. × cymosus, a group which has ‘Conquête’ as its type. Others in this group are (to name only those treated here) ‘Rosace’, ‘Norma’, ‘Albâtre’, and ‘Voie Lactée’. But there seems to be no very clear-cut distinction between this group and Rehder’s P. × polyanthus, which has a similar inflorescence but hairy calyces. The type of this group is ‘Gerbe de Neige’, which is apparently not in commerce in Britain. ‘Boule d’Argent’ belongs to it, and perhaps ‘Favorite’.

Some of Lemoine’s finest hybrids have a pinkish or purplish blotch at the base of the petals and derive from a plant received by him as P. coulteri. The plant grown in British gardens under this name is a form of P. mexicanus (q.v.) and Lemoine’s plant, judging from its offspring, must have been similar, if not the same. The first of these bi-coloured hybrids was ‘Fantaisie’ (1900), which is believed to be a cross between “P. coulteri” and ‘Lemoinei’. This had indistinctly marked flowers, but in ‘Purpureo-maculatus’ (1902) the blotch is more pronounced. Both seem to be now rare in gardens, and the same is true of many others in this group. These were put into commerce by Lemoine during the first world war and may never have been introduced to Britain. But it is doubtful if any of these could be better garden plants than ‘Sybille’ (date of origin uncertain) and ‘Belle Étoile’ (1923). The researches of Dr Janaki Ammal have shown that both these clones, and also ‘Bicolore’, are triploid (Journ. R.H.S., Vol. 76 (1951), p. 273).

‘Albâtre’. – Flowers 112 in. wide, fragrant, double, but with a few fertile stamens. Inflorescence racemose, with jointed pedicels, or the lower peduncles branched and two-flowered. Calyx almost glabrous. Leaves on the flowering shoots narrow-ovate, up to 112 in. long, sparsely toothed. 4 to 5 ft. Early July.

‘Argentine’. – Flowers fragrant, about 2 in. wide, very double, borne mostly in threes. Sepals often six instead of the usual four. 3 to 4 ft.

‘Atlas’. – Flowers slightly fragrant, single, cup-shaped, 112 in. wide, in racemes of five or seven. Calyx sparsely hairy. Leaves on flowering shoots sparsely toothed, up to 212 in. long, 1 in. wide. 4 to 6 ft. A.M. 1927.

‘Avalanche’. – Flowers fragrant, cruciform, 34 to 1 in. wide, borne in racemes of mostly seven. Leaves elliptic, acute at both ends, glabrous, entire Hu, Journ. Arn. Arb., Vol. 37, p. 64). Of arching and very spreading habit, as shown in Gard. Chron., Vol. 18 (1897), p. 89. A.G.M. 1936. Although the true ‘Avalanche’ must be in cultivation, it appears to have become confused with ‘Erectus’ (q.v.).

‘Beauclerk’. – Flowers fragrant, white with a slight pinkish flush in the centre, up to 3 in. wide, saucer-shaped at first, becoming flat, solitary or in clusters of three or four (occasionally up to seven); petals roundish oblong, irregularly toothed. Stamens spreading, with conspicuous bright yellow anthers. Leaves on the sterile growths broad-ovate, acute, with a few mucronate teeth on each side, up to 212 in. long, those on the flowering twigs smaller and less toothed. It attains 6 ft in height, more in width. Raised by the Hon. Lewis Palmer from a cross made in 1938 between ‘Sybille’ (seed-parent) and ‘Burfordensis’. A.M. 1947, F.C.C. 1951, A.G.M. 1957.

‘Belle Étoile’. – Flowers very fragrant, with a conspicuous reddish blotch in the centre; petals broadly oblong, at first spreading-erect and slightly folded down the centre, so that the flower is rather angular, later spreading more widely. Inflorescence variable, in its complete form a compound cyme of nine flowers. Leaves on the flowering twigs narrow-ovate, long-pointed, scarcely toothed or entire, but those immediately under the inflorescence bract-like. Leaves on the sterile growths ovate, acuminate, up to 312 in. long, with a few large teeth on each side. A lovely, deliciously scented philadelphus usually 5 to 6 ft high, more in width, very free-flowering. A.M. 1930, A.G.M. 1936.

‘Bicolore’. – Flowers fragrant, single, cup-shaped, about 134 in. wide, mostly solitary; petals creamy white with a flush of purple at the base. Leaves on the flowering shoots entire or sparsely toothed, ovate, mostly 114 in. long, 34 in. wide, uniformly covered with appressed silky hairs beneath. Of dwarf habit.

‘Boule d’Argent’. – Flowers 134 in. wide, scarcely fragrant, more or less double, borne five to seven together in a cymose cluster. Calyx-tube slightly hairy, sepals long-acuminate, glabrous. Leaves up to 212 by 178 in., broad-ovate, with five to seven teeth on each side. Of bushy habit, to about 4 ft high. F.C.C. 1895.

‘Bouquet Blanc’. – There appears to be some confusion between this variety and ‘Albâtre’ and the two are treated as synonymous by Dr Hu (Journ. Arn. Arb., Vol. 37, p. 60). A plant under the name ‘Bouquet Blanc’ has not been seen, but a photograph reproduced in Journ. R.H.S., Vol. 38 (1912–13), fig. 116, shows a plant with semi-double to almost single flowers (with some petaloids), whereas ‘Albâtre’ has almost fully double flowers. A.M. 1912.

‘Burfordensis’. – Flowers 212 to 3 in. across, not fragrant, in racemes of five to nine, stamens with conspicuous yellow anthers. Calyx-tube glabrous, sepals very sparsely hairy. Leaves up to 412 in. long by 2 in. wide, coarsely toothed, often deeply so. A very vigorous, free-flowering hybrid, attaining 10 ft in height, but less in width. It is difficult to believe that this philadelphus is the true ‘Burfordensis’, which received an Award of Merit when shown by Sir W. Lawrence of Burford Court, Dorking, in 1921. This was said to be a sport of ‘Virginal’, whereas the plant now grown under the name does not even belong to the Virginalis group, but bears some resemblance to ‘Monster’. It was, however, raised at Burford Court.

‘Burkwoodii’. – Flowers very fragrant, about 134 in. wide; petals relatively narrow, acute, not overlapping, stained purplish pink at the base. Inflorescence cymose, with three to five flowers, or the flowers solitary. Calyx-tube and sepals sparsely hairy. Leaves on the flowering shoots 58 to 112 in. long, up to 58 in. wide. Raised by Messrs Burkwood and Skipwith shortly before 1931; the parentage is said to be ‘Étoile Rose’ crossed with ‘Virginal’.

‘Conquête’. – Flowers shaped rather as in Clematis montana, very fragrant, about 2 in. wide, single or with a few petaloid stamens, borne in compound cymes of three or five, the lateral peduncles jointed. Calyx-tube and outside of sepals glabrous, the latter long-acuminate. Leaves on flowering shoots lanceolate, up to 4 in. long, entire. A low-growing shrub, 3 to 4 ft high. It is the type of the Cymosus group. ‘Rosace’ is similar, but the flowers are semi-double and it is taller growing.

‘Coupe d’Argent’. – Flowers solitary or in twos or threes, rose-scented, at first saucer-shaped, becoming flat, about 214 in. wide; the petals broadly rounded and overlapping, so that the flower is squarish in outline. Leaves entire or slightly toothed, narrow-ovate, up to 212 in. long, 114 in. wide. Weak-growing but very beautiful. The description is of the plant in commerce here, but it is doubtful if the name is correct. According to the earliest description that can be traced, Lemoine’s ‘Coupe d’Argent’ had long arching branches and pure white flowers of perfect form 1 in. wide (Le Jardin, Vol. 30, no. 749 (1921), p. 36).

‘Dame Blanche’. – Flowers slightly fragrant, broad-campanulate, about 1 in. wide, double or semi-double, up to nine in a raceme. Leaves dark green, smooth and almost glabrous above, slightly hairy beneath, narrowly to broadly ovate, 334 to 6 in. long, 112 to 258 in. wide, with a few distant, shallow teeth. A very attractive philadelphus of moderate growth. The description is from a plant at Wisley, which belongs to the Virginalis group. ‘Dame Blanche’, as described by Dr Hu in her monograph, is evidently different and belongs to the Lemoinei group.

‘Enchantement’. – Flowers faintly fragrant, double, 34 to 114 in. wide, up to eleven crowded in a short raceme (about 2 in. long); outer petals rounded at apex. Calyx and pedicels hairy. Leaves on the extension growths about 212 by 112 in., with three or four coarse teeth on each side. It is a vigorous shrub with arching branches, attaining 7 ft, very free flowering. A.M. 1966.

‘Erectus’ (‘Lemoinei Erectus’). – Flowers fragrant, creamy white, cruciform, 1 in. or slightly more wide, borne in threes or fives. Leaves on the flowering shoots ovate-lanceolate, acuminate, rounded or broad-cuneate at the base, 78 in. long, 38 in. wide, entire or with a few sharp teeth; on extension shoots up to 138 in. long, 58 in. wide. Of erect, close habit, to about 4 or 5 ft; on young or heavily pruned plants the habit may be more lax. Some plants distributed as ‘Avalanche’ belong here.

‘Étoile Rose’. – Flowers fragrant, solitary or in twos or threes, saucer- shaped at first, becoming flat, 112 to 134 in. wide; petals stained rose at the base, broad-oblong; sepals caudate, the tails 14 in. long. Leaves narrow-ovate, entire or with a few mucronate teeth, up to 3 in. long, 118 in. wide. Of dwarf habit.

‘Girandole’. – Flowers milky white, fully double, 1 to 112 in. wide, up to nine crowded in a roundish, racemose cluster. Calyx sparsely hairy. Leaves on the extension growths up to 2 in. long, 114 in. wide, with four or five well-defined teeth on each side. 4 to 6 ft. A.M. 1921.

‘Glacier’. – Flowers fully double, fragrant, only 114 in. wide, borne in racemes of five to nine. Leaves mostly less than 134 in. long, toothed. Calyx hairy. 4 to 5 ft high.

‘Innocence’. – Flowers single or with a few petaloid stamens, about 112 in. wide, five to seven in a cluster. Leaves mottled with yellow, up to 2 in. by 1 in., with fairly numerous small teeth.

‘Lemoinei’. – Flowers pure white, very fragrant, 1 in. or slightly more wide, produced at the ends of short lateral branches, three to seven in each. Leaves on the sterile growths ovate, rounded at the base, slender-pointed, with usually three to six coarse teeth on either margin, 1 to 212 in. long and about half as wide, dull green and with scattered hairs above, glossy and more hairy beneath. Leaves on the flowering shoots about 1 in. long, narrowly ovate, almost entire.

This hybrid, the type of the Lemoinei group, was raised by Lemoine around 1883, by crossing some garden form or hybrid of P. coronarius with P. microphyllus. See further in the introductory note above. It makes a round-topped bush 6 ft or more high, but seems to have become uncommon. A.M. 1898.

‘Manteau d’Hermine’. – Flowers creamy white, fragrant, 34 to 112 in. wide, borne mostly in threes, sometimes in fives. Leaves almost entire, those on the flowering shoots mostly less than 112 in. long. Of dwarf, compact habit. A.M. 1956.

‘Minnesota Snowflake’. – Flowers white, fragrant, fully double, in racemes of up to nine, about 134 in. wide, the inner petals mostly narrow and acute. Sepals narrowly triangular or lanceolate, slightly hairy. Raised in the USA by G. D. Bush of Minneapolis, Minnesota, and patented in 1935. Of mounded habit, up to 8 ft high. ‘Frosty Morn’ is a newer hybrid from the same raiser, smaller growing. Both are available in commerce in Britain but their chief value is their great hardiness, which permits them to be grown in the colder parts of the USA and Canada, where most philadelphus cannot survive the hard winters.

‘Monster’. – Flowers single, about 2 in. wide, cup-shaped at first, flatter when fully expanded, up to nine in a raceme. Calyx sparsely hairy. Leaves large even on the flowering shoots, where they may be 6 in. or so long, half as wide. A coarse, vigorous shrub, quickly growing to 10 ft and eventually much taller. It is near to P. pubescens and was apparently named and distributed by Messrs V. N. Gauntlett of Chiddingfold. It reached a height of 25 ft at Nymans in Sussex (Gard. Chron., Vol. 120 (1946), p. 219). It is possibly a form of P. × monstrosus (Spaeth) Rehd., believed to be a hybrid between P. pubescens and P. lewisii var. gordonianus, though it differs from Rehder’s description in having more strongly toothed leaves.

‘Norma’. – Flowers fragrant, saucer-shaped, about 134 in. wide, single or occasionally with a few petaloid stamens, borne in fives or threes in a cymose cluster. Calyx almost glabrous; sepals long-acuminate. Leaves ovate, toothed, up to 2 in. long on the flowering shoots. One of the finest of the single-flowered hybrids, with arching branches and 4 to 5 ft high. A.M. 1913, A.G.M. 1949.

‘Patricia’. – Flowers single, fragrant, about 114 in. wide, in racemes of five or seven. Leaves remarkable for their dark green colouring and rather leathery texture; they are almost entire, ovate, acute, glabrous beneath except for axillary tufts, up to 234 in. long, 112 in. wide. Raised by the well-known Canadian plant-breeder F. L. Skinner. In cultivation in the Royal Horticultural Society Garden at Wisley.

‘Purpureo-maculatus’. – Flowers fragrant, 112 in. across, solitary at the end of a short lateral branchlet; petals white with a blotch of purplish rose at the base, opening in mid-June. Leaves on the sterile shoots broadly ovate or roundish, the base slightly heart-shaped, up to 134 in. long, 112 in. wide, with one to three teeth each side, dull dark green; leaves on the flowering twigs 1 in. or so long, with usually one tooth or entire. Bot. Mag., t. 8193. A dwarf shrub, 2 or 3 ft high. It is the type of the Purpureo-maculatus group, see further in introductory note.

‘Rosace’. – See under ‘Conquête’.

‘Silver Showers’ (‘Silberregen’). – Flowers 134 in. wide, fragrant, single, mostly solitary at the ends of the twigs, flat, with four or sometimes five petals. Leaves slightly hairy, ovate, up to 112 in. long, acute, with two or three teeth on each side. 3 ft or slightly more high, making a rounded bush. A promising hybrid of German origin, recently introduced, It is near to the Lemoinei group.

‘Sybille’. – Flowers fragrant, saucer-shaped, up to 2 in. wide, solitary or in two or threes (occasionally an extra one or two flowers are produced lower down in the leaf-axils). Petals fimbriated, marked purplish rose at the base, or sometimes with a broad stain of that colour extending half-way to the apex. Leaves broad-ovate, sea-green when mature, up to 134 in. long on the flowering twigs. Young stems pinkish, hairy. A lovely philadelphus, very free-flowering and graceful, one of the best for small gardens. It is rarely more than 4 ft high, 6 ft wide. A.M. 1954.

‘Velleda’. – Flowers saucer-shaped, about 2 in. wide, very sweetly rose-scented, mostly solitary at the ends of the lateral twigs; petals rounded. Leaves up to 214 by 118 in., mucronate-toothed or entire. Of fairly dwarf habit. A beautiful, little-known hybrid of uncertain position. Despite the unblotched flowers it seems to derive from the Purpureo-maculatus group.

‘Virginal’. – Flowers white, fragrant, cup-shaped, 2 in. wide, double or semi-double, the true petals and outer petaloids rounded. Calyx rather densely hairy. Leaves ovate, up to 134 in. long, 1 in. wide on the flowering twigs, twice as large on the sterile growths, coarsely toothed, but the smaller leaves with obscure, mucronate teeth. This is perhaps the most widely planted of the hybrids and one of the most beautiful in flower, but it is of gaunt habit; height 6 to 8 ft. F.C.C. 1911, A.G.M. 1926. It is the type of the Virginalis group, see introductory note above.

‘Voie Lactée’. – Flowers slightly scented, saucer-shaped at first, becoming flat, with the petals then slightly reflexed, 2 in. or slightly more wide, solitary or in cymose clusters of three or five; petals occasionally five or six instead of the usual four. Calyx almost glabrous. Leaves on the flowering shoots up to 278 in. long, 114 in. wide, slightly toothed. One of the most beautiful of the single-flowered hybrids. Height 4 to 5 ft. A.M. 1912.