A deciduous shrub, usually with many fairly steeply ascending stems from the base and of graceful, open habit, becoming more spreading when old; sometimes a small tree on a single trunk; winter-buds narrowly ovate, acute, red-tinged on the exposed side, except in shade. Young twigs shaggy with white hairs at first, soon glabrous. Leaves of fertile branchlets elliptic, oblong-elliptic, or oblong-obovate (broadest just above the middle), obtuse to subacute or bluntly short-acuminate, mostly rounded, sometimes slightly cordate, at the base, 13⁄4 to 31⁄4 in. long, 11⁄4 to 1[5/4] in. wide, hairy beneath when quite young, soon glabrous, finely toothed, with about twelve to twenty teeth per inch on each side (leaves on sterile shoots more coarsely toothed); petioles 3⁄8 to 1⁄2 in. long. Inflorescence a raceme 2 to 3 in. long from the lowermost flower, composed of mostly seven to twelve flowers, terminating a leafy shoot and pointing in the same direction as the shoot or slightly upcurved. They are produced end-April or early May, when the leaves are about half their full size and are either still closely folded along the midrib and purplish but mostly with the two halves coming apart, or almost flat and then a soft copper-colour. Pedicels and rachis hairy at first, the lowermost of the former 3⁄4 to 1 in. long, reducing to half that length near the apex. Calyx-tube at first hairy in the lower part. Sepals awl-shaped, hairy mostly on the inside and at the edge. Petals five, white, oblanceolate to elliptic, mostly obtuse, about 5⁄8 in. long and just under 1⁄4 in. wide. Stamens about twenty. Top of ovary glabrous. Fruits ripe soon after midsummer, round, about 3⁄8 in. wide, the persistent sepals erect to spreading (not reflexed).
Although originating, directly or indirectly, from eastern North America, this amelanchier has become virtually a native of south-eastern England, from Dorset to Kent; it also occurs in Holland, especially around Dwingeloo, and in north-west Germany. A favoured habitat is in open woodland of oak, birch and pine, on sandy, acid soils, and it will even flourish where the ground is very peaty and water-logged in winter. Long identified with A. canadensis, and later with A. laevis, it was given its present name by the German botanist F.-N. Schroeder in 1968 (Taxon, Vol. 17, pp. 633-4 (1968); Watsonia, Vol. 8, pp. 155-62 (1970), in English; Abhandl. Naturf. Ver. Bremen, Vol. 37 (3), pp. 287-419 (1972), a paper dealing also with two other amelanchiers naturalised in Europe).
A. lamarckii is most probably a microspecies of hybrid origin. One parent must be A. laevis, from which it takes the beautiful colouring of the unfolding leaves and its large flowers. The other parent might be A. canadensis, which it resembles in the shape of its leaves, and the erect-spreading posture of the sepals of the fruits, and from which it may derive the hairiness of the young leaves and inflorescences. A. arborea × A. laevis has been suggested, but this is most unlikely (see below, under A. × grandiflora).
A. lamarckii breeds quite true from seed, as is evident from a natural stand on the Surrey – Sussex border, where plants of widely different ages are uniform in foliage and flower. This behaviour is not surprising in an ally of Sorbus, a genus in which numerous microspecies of hybrid origin are recognised by European botanists.
Whether A. lamarckii arose in Europe or came from eastern North America in its present form it is impossible to say. It is certainly an old inhabitant of Surrey. In 1893 it was already established on Hurtwood Common between Ewhurst and Peaslake and elsewhere in the Lillingbourne valley, also in copses around Witley and Thursley (Dunn, Fl. SW Surrey, 1893). It could hardly have attained even this small range unless it had been introduced much earlier in the century, and there is nothing inherently unlikely in Schroeder's suggestion that the amelanchier described by Lamarck in 1783 from a plant cultivated in Paris and named by him Crataegus racemosa is really A. lamarckii. This, incidentally, explains the specific epithet chosen by Schroeder – the combination Amelanchier racemosa (Lam.) would be illegitimate, as this name had been applied by Lindley to the shrub now known as Exochorda racemosa. However, the identity of Lamarck's amelanchier is immaterial, since the type of A. lamarckii was collected by Schroeder himself in Germany. It is probable that a good match could be found for A. lamarckii in American herbaria, but it would be impossible to tell from an herbarium specimen whether it represented a true-breeding microspecies or a chance hybrid of similar appearance. It is conceivable that the stand from which A. lamarckii came originally no longer exists, assuming of course that it did come from America in the first place. See further below, under A. intermedia.
A. lamarckii is perhaps the finest of the amelanchiers in flower, owing its beauty then to the background of young leaves, which are coloured almost like those of the cherry 'Tai Haku' during its flowering time. But only when seen by the hundred in light woodland is its full beauty revealed. In autumn the leaves turn red and orange in sun, yellow in shade.
In Germany and Holland A. lamarckii is known by names meaning 'currant tree', and in the past its fruits were dried and used as currants, or stewed or made into jam. The fruits are also much liked by blackbirds and thrushes, which take them before they are fully ripe, when the seeds are fortunately already viable.
A. intermedia Spach – This was described in 1834 from an amelanchier grown in France and said to be not uncommon in gardens there. It has been suggested that the amelanchier in question was A. lamarckii, but this is very unlikely, since Spach's detailed description does not agree with it in several important particulars. Spach sent a flowering specimen to the American botanist Asa Gray, which was preserved in the Gray Herbarium. From this, Wiegand concluded that A. intermedia agreed with an amelanchier occurring in the mountains of the eastern USA from Vermont to North Carolina, which he considered to be intermediate between A. canadensis and A. laevis (Rhodora, Vol. 22, p. 147 (1920)). A. lamarckii, too, is intermediate between these two species but differs from A. intermedia, as described by Spach, in its fruits with erect (not reflexed) sepals, and from Wiegand's interpretation of A. intermedia in its much longer racemes and larger flowers.
A. × grandiflora Rehd. A. botryapium lanceolata Hort. Simon-Louis; A. canadensis grandiflora Zab., nom. nud. – A hybrid between A. arborea and A. laevis, which occurs in the wild, but was described by Rehder in 1920 from a plant in the botanic garden at Hannover-Muenden, Germany, which had been received from the French nursery of Simon-Louis before 1878. It takes from both parents the shape of its leaves, the flexuous inflorescences and the soon reflexed sepals. It resembles A. laevis in its tinted young leaves, which are hairy beneath when young, and the flowers are more numerous in each raceme, on shorter perdicels. From A. arborea it differs in the coloured young foliage, the larger flowers and juicy fruits.
It has been suggested that A. × grandiflora and A. lamarckii are identical. In fact they differ substantially. The leaves of A. lamarckii are never, or at least very rarely, ovate as in A. × grandiflora, nor so acuminate; its racemes are not flexuous; its sepals are not reflexed.
The original clone of A. × grandiflora was put into commerce under its present name after 1920, but had in fact been received at Kew in 1893 direct from Simon-Louis, as 'A. lanceolata', and was identified there as A. canadensis.
Unfortunately, owing to the confusion between A. lamarckii and A. × grandiflora and consequent mislabelling, no authentic mature plant of the latter has been seen, and the above account has perforce to be based on the original description and authentic herbarium specimens. But in the USA, A. × grandiflora is considered to be the finest of the taller amelanchiers in flower. It is said to be of spreading habit, which is true of A. lamarckii only when the plant is very old. It is very likely that the 'A. laevis' of Dutch nurseries is A. × grandiflora; certainly it agrees very well with it, judging from a young plant kindly supplied by Mr Harry van de Laar.
It should be added, to avoid further confusion, that the name A. grandiflora was applied by Wiegand to a quite different amelanchier, a relative of A. sanguinea (q.v.). But Rehder's use of the name has priority.
cv. 'Rubescens'. – Resembling the type, but the flowers purplish pink in bud and suffused pink when opening. A seedling of A. arborea raised in the Durand-Eastman Park at Rochester, New York, before 1920. A. laevis, undoubtedly the other parent, grew nearby.
A. 'Ballerina'. – A vigorous, erect shrub or small tree, ultimate height unknown. Leaves slightly glossy, mostly broad-elliptic and 2 to 3 in. long, 11⁄4 to 15⁄8 in. wide, shortly acuminate, finely saw-toothed, almost glabrous even when young, and then slightly bronze-tinged. Flowers about 1 in. or slightly more wide, six to eight together in somewhat nodding, glabrous racemes. Calyx-tube glabrous; sepals hairy on the inside, slowly reflexing after flowering. Fruits ripe in July, at first bright red, dark purple when ripe, juicy and sweet, about 1⁄2 in. wide.
A hybrid of A. laevis, of which the other parent is uncertain. The original plant was received at the Boskoop Experimental Station in 1970 from Messrs Hillier under the erroneous name of 'A. ovalis', but almost certainly came originally from a continental nursery. It was named and described by Harry van de Laar in 1980 (Dendroflora No. 17, pp. 3-5). It has been suggested that it is a cultivar of A. lamarckii, but it is impossible to accept this conclusion.
'Ballerina' is remarkably floriferous, the racemes being borne close together at the tips of the previous season's growths. But the autumn colour is less remarkable, a dark, purple-brown. It is already in commerce in Britain.
The author is grateful to Mr Harry van de Laar for plants and leaf-specimens of some of the cultivars discussed above.