Soon after the introduction of C. japonica in 1869 spontaneous hybrids began to occur between it and C. speciosa, but their mixed parentage was not at first suspected and they were put into the trade as forms of “Cydonia maulei”, which is the name under which C. japonica was first grown. The first of these to be recognised as a hybrid had been named var. superba, which by Rehder was made the type of the hybrid group C. × superba (Frahm) Rehd. To it belong many of the smaller chaenomeles grown in gardens at the present time.
Generally they are low, spreading shrubs to 4 or 5 ft high. In foliage they are intermediate between the two parents (leaves coarsely toothed in C. japonica, 1 to 2 in. long, obovate or rounded: finely toothed in C. speciosa, up to 31⁄2 in. long, ovate or oblong). In the character of the shoots they incline towards C. japonica (downy and rough the first year, warty in the second; in C. speciosa the young growth is smooth and glabrous or only slightly downy and the second-year twigs are smooth also). Colour ranges through the whole gamut from white, pink, and crimson to various shades of orange and orange-scarlet. The following is a selection of some of the better-known forms:
‘Boule de feu’. – Flowers orange-scarlet; fruits bright yellow. This and its sister seedling ‘Vermilion’ are of interest as the first deliberate crosses between C. speciosa and C. japonica; they were raised by Barbier of Orleans in 1913.
‘Coral Sea’. – Flowers of the unusual and attractive shade known as Chinese Coral (HCC 614/1); it grows to about 3 ft high. ‘Yaegaki’, a clone of Japanese origin, has flowers of the same colour, but they are double and the plant is of very dwarf habit.
‘Crimson and Gold’. – A dense, spreading shrub to 3 ft high; flowers large, deep red, with golden anthers. Raised by W. B. Clarke of California and put into commerce in 1939. It is said to be invasive and suckering on some soils.
‘Knap Hill Scarlet’. – An old variety, raised by Anthony Waterer around 1870; of low, spreading habit; flowers large, brilliant red, very freely borne.
‘Rowallane’. – Of low, spreading habit in the open ground, but makes a good wall plant. Flowers to 11⁄2 in. across, brilliant crimson. Raised at Rowallane, Co. Down, in 1920.
C. × californica Weber – By crossing C. cathayensis with a form of C. × superba, the late W. B. Clarke of California founded a new hybrid group in which all three species of Chaenomeles are united. So far, according to Weber, the cross has not been repeated, the forms put into commerce being seedlings from the original cross and their offspring (some of which may be back-crosses). All so far distributed are erect spiny shrubs of stiff habit, with lanceolate leaves; the flowers are in shades of pink and rose red and remarkable for their size, which may be 2 in. across in some of the forms.
Some of the cultivars of C. × californica have been introduced to Kew, where they grow well both as lawn specimens and on walls, and bear handsome, bright yellow fruit. There are several named clones in commerce in the U.S.A., of which one of the finest is said to be ‘Cardinal’.