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A group of hybrids between H. japonica and H. mollis, originally described by Rehder in 1945 from plants growing in the Arnold Arboretum, the seed parent of which was H. mollis (the Wilson introduction), and the pollen parent a yellow-flowered H. japonica. The foliage of these hybrids was described by Rehder as being intermediate between those of the parents in shape and indumentum. It is very likely that some of the seedlings of H. mollis raised and distributed over the past half-century belong to H. × intermedia. At any rate, plants under the name H. mollis have been noted which differ from that species in having the leaves narrower at the base, darker green above, more sparsely downy beneath and with longer and more slender stalks.
Some of the best known witch-hazel hybrids were raised at Kalmthout in Belgium, where as early as 1902 the nurseryman Kort had a collection of the species and cultivars then known (Rev. Hort. Belg., Vol. 28 (1902), p. 61). Later he must certainly have added the newer introductions, including H. mollis and H. japonica var. flavopurpurascens. In the late 1920s this nursery fell into decay, but after the second world war part of the site was purchased by MM. Georges and Robert de Belder, who have carried on the work started by Kort. In a lecture to the Royal Horticultural Society Robert de Belder said of these Kalmthout hybrids: ‘I am still doubtful about the origin of our plants. I presume that they were originally seedlings of a plant labelled H. japonica var. flavopurpurascens. There are two possibilities: either the plant that we grow at Kalmthout under that name is hybrid already or the plant, being a form of japonica, has been pollinated by mollis and, subsequently, by intermediate forms. Either way, the large intermedia plants that we grow show hybrid vigour and are very fertile. This enables us to raise thousands of seedlings for selection. Flower colour varies from pale to dark yellow, orange, red and dark red’ (Journ. R.H.S., Vol. 94 (1969), p. 85).
Varieties of H. × intermedia have also been raised in Britain, Denmark, Germany and Japan. The following is only a selection, and further information can be found in the works cited in the introductory note to Hamamelis.
’Arnold Promise’. – An interesting feature of this cultivar is that it does not bloom until March, a character inherited from its pollen-parent H. japonica ‘Zuccariniana’. See further in Arnoldia, Vol. 41, pp. 30–33 (1981).
† ‘Diane’. – Flowers opening in February, uniform rich red. Award of Merit 1969, when exhibited by its raiser Robert de Belder. The leaves colour well in the autumn. This is an improvement on ‘Feuerzauber’.
† ‘Primavera’. – Another of the Kalmthout hybrids raised by M. de Belder. Flowers primrose-yellow in February, so starting to bloom just as H. mollis ‘Pallida’ is going over.