Deciduous tree to about 6 m, with pendulous branches, a graft hybrid between Mespilus germanica and Crataegus monogyna. Branches variously intermediate between the parents, sometimes with some branches exactly resembling one or the other parent.
+ Crataegomespilus dardarii is of great interest (if not always of great beauty) as one of only two woody graft hybrids which are at all well known (see also + Laburnocytisus adamii). Such hybrids form at graft unions, rarely. Tissues of the two species remain more or less distinct, sometimes as layers, within a shoot. Each cell belongs unambiguously to one or the other parental species in genetic terms, although the proximity of alien tissue may affect their development, resulting in genuinely intermediate characteristics (Byatt, Ferguson & Murray 1977). The medlar–hawthorn graft hybrid has arisen on at least three independent occasions (Byatt, Ferguson & Murray 1977), thanks to the practice of grafting quince cultivars onto hawthorn rootstocks. This led to an unhelpful trail of historical names, although material seen today might well all be from the first and best-known origin. Since these are inherently unstable plants, distinct intermediate forms barely qualify as cultivars even if named as such, and more than one may appear spontaneously on a single tree.
The first known origin was in the garden of a M. Dardin at Bronvaux, near Metz, France, in the late 19th century. Two branches, both intermediate but not alike, emerged just below a graft union; they were shown to the nearby Simon-Louis nursery in 1895 (Bean 1976). These branches were themselves propagated by grafting and distributed.
The first form, labelled simply as + C. dardarii or as a cultivar ‘Dardarii’, tends towards Mespilus. It was described by Bean (1976) as having downy, more or less spiny branchlets, oblong, oval or ovate oblong; leaves 4–10 × 2.5–4.5 cm, entire or very finely toothed, downy on both sides, with a 3 mm petiole; white flowers 4 cm across, up to 12 in a corymb, on downy 1–2.5 cm pedicels; calyx with five narrow, pointed lobes 8–13 mm long, very downy; and fruit medlar-like, but smaller and in clusters.
The second form has been variously labelled + C. asnieresii, or as a cultivar ‘Asnieresii’ or better (an earlier name) ‘Jules d’Asnières’. It tends more to the Crataegus parent. Bean (1976) considered it beautiful, describing it as having wooly branchlets, with occasional haythorn-like spines; leaves obovate to broadly ovate, 4–7.5 × 2.5–4.5 cm, some entire, others deeply lobed as in Hawthorn, mealy-looking when young, softly downy beneath; flowers in corymbs, Hawthorn-like but larger and with a downy calyx; petals white, rose-tinted with age; fruit oblong, brown, downy, roughly Hawthorn-sized.
These two states form part of a transitional series, and one cannot expect a tree propagated from either to remain ‘pure’; branches of another intermediate, or of either parent may appear (Byatt, Ferguson & Murray 1977; Bean 1976). Owen Johnson notes a specimen planted in 1976 on the University of Surrey campus which by 2018 appeared to be purely Mespilus (The Tree Register 2023).