Cornus alba L.
Synonyms: C. sibirica Raf.; C. tatarica Mill.; Swida alba (L.) Opiz; Thelycrania alba (L.) Pojark.
A deciduous, wide-spreading shrub, producing a thicket of stems erect to prostrate; ultimately 10 ft high. Bark of the young shoots becoming in autumn and winter rich red. Leaves opposite, ovate to oval, rounded or wedge-shaped at the base, with short slender points; variable in size, but usually from 2 to 41⁄2 in. long; dark green above, glaucous beneath, with minute flattened hairs on both sides; veins in about six pairs; stalks 1⁄3 to 1 in. long. Flowers small, yellowish white, in cymes 11⁄2 to 2 in. across. Fruit whitish or tinted with blue, about the size of a pea. Stones longer than wide, flattened at each end.
Introduced from Siberia in 1741, and a native also of China. This is a rampant shrub, apt to smother anything less vigorous than itself growing near. It is therefore best adapted for forming an isolated mass on a spacious lawn, or on the banks of a pond, where its deep red stems are remarkably effective all through the winter. A number of varieties are in cultivation, of which the following form a representative set:
cv. ‘Elegantissima’. – Leaves with an irregular margin of creamy white, centre grey-green; winter-stems red. Also known as ‘Sibirica Variegata’; both names are in use, but the one adopted here seems to be the better established, at least in this country. The epithet argenteo-marginata has been applied both to this clone and to ‘Variegata’, but is not a valid name for either.
cv. ‘Gouchaultii’ . – A variegated form, margined with yellow and stained with rose. It is duller than ‘Spaethii’, and with more green and rose in the centre. ‘Froebelii’ and ‘Tricolor’ differ but little and are no better.
cv. ‘Kesselringii’. – Branchlets dark brownish purple; unfolding leaves reddish.
cv. ‘Sibirica’. – Not so rampant a grower as the type, the branches of a paler and brighter red; fruit bluish; leaves mostly more rounded and more shortly acuminate at the apex. The plants that correctly bear this name were put into commerce by Loddiges as “Cornus sibirica” and described by Loudon under the name C. alba var. sibirica. Unfortunately, some nineteenth-century botanists, believing that the C. alba of Linnaeus was the American red osier dogwood (properly C. stolonifera), used the name C. alba var. sibirica for the Siberian dogwood in general, which may explain why some of the plants in commerce as C. alba sibirica are typical C. alba and not the true ‘Sibirica’.
The plants grown as “Westonbirt”, “the Westonbirt dogwood” or atrosanguinea do not, judging from the trials at Wisley, differ in any way from the true ‘Sibirica’. It is at present represented at Westonbirt only by a few plants in the home nursery; the common dogwood there is ordinary C. alba.
‘Sibirica’, being of rather weak constitution, should be grown in a damp, well-cultivated soil. The bark is most brightly coloured on the previous summer’s growths and gradually darkens as spring approaches.
cv. ‘Spaethii’. – Undoubtedly the handsomest of all the variegated cornels, and perhaps the most effective of all deciduous, yellow-variegated shrubs in cultivation. A mass on a lawn has a most striking aspect all the summer through, for the plant has the great virtue of never having its foliage scorched by summer sun, although the major part of the leaf is bright yellow; nor does it become dull as the season advances, like many shrubs of this colour do. When visiting Spath’s nursery at Rixdorf, near Berlin, many years ago, I was told that this remarkable shrub originated there on a stem of ordinary Cornus alba, on which had been grafted a scion of the variegated sort. The graft died, but just beneath the point of union a yellow variegated twig appeared, which was removed and propagated, and is the ‘Spaethii’ as we know it today. The bark is red in winter. The shrub does not need a very rich soil, and like the rest of the forms of C. alba, can be propagated by cuttings of leafless wood placed in the open ground in late autumn, or by late summer leafy shoots under glass. The outer branches can be easily layered.
cv. ‘Variegata’. – Leaves margined with creamy white. ‘Elegantissima’ is less vigorous and often preferable.
From the Supplement (Vol. V)
cv. ‘Elegantissima’. – It was stated that ‘Sibirica Variegata’ is an alternative name for ‘Elegantissima’. In fact, two distinct clones are involved. The true ‘Sibirica Variegata’, which is still grown and propagated in Holland, has broader leaves than ‘Elegantissima’, and there is a pink flush in the marginal variegation. It makes a smaller, sturdier plant, and is hardy even in the coldest parts of Canada, where ‘Elegantissima’ does not succeed. We are grateful to Mr H. J. van de Laar for this information.
cv. ‘Sibirica’. – Graham Thomas tells us that another reason why this dogwood did not thrive in the open at Westonbirt was that it was continually eaten by rabbits. This information came from John Mitchell, who was for many years Curator of the Westonbirt collection. It should be emphasised that the name “Westonbirt dogwood” is applicable only to this very distinct clone, with rather slender stems of the brightest red, but is often misapplied in the trade to ordinary C. alba.
cv. ‘Spaethii’. – The true cultivar is becoming uncommon in the trade. In recent trials held at the Long Ashton Research Station, it was found that of the samples received under this name from eleven nurseries only one was correctly named, the others being C. alba ‘Gouchaultii’ (Gard. Chron., April 11, 1980, p. 25). The true ‘Spaethii’ is not a strong grower, but has a well-marked golden edge to the leaf; ‘Gouchaultii’ is more vigorous, but the colouring is much duller.