First blooming of a new intergeneric hybrid between Chaenomeles and Pyrus (Rosaceae)

Remote hybridization plays an important role in the evolution and breeding of plants, especially in subtribe Malinae (Rosaceae). The study deals with the issues of introducing and flowering of a new artificial intergeneric hybrid ×Pyromeles (= Chaenomeles × Pyrus). The Japanese quince (Chaenomeles japonica) is a plant that is widely appreciated for its ornamental qualities and is being considered as a novel and promising fruit option. Following the apple tree, the pear (Pyrus communis) is recognized as the second most important pome crop. There are natural and artificial intergeneric hybrids derived from Pyrus such as ×Pyraria (= Aria × Pyrus), ×Pyronia (= Cydonia × Pyrus), ×Pyralus (= Malus × Pyrus), and ×Sorbopyrus (= Pyrus × Sorbus), which have nutritional value and are also used as rootstocks, virus indicators, and in the breeding of pears and other pome fruit crops. Many scientists have crossed Japanese quince with quince, pear, rowan and apple trees in the last century, but no true hybrids have been produced. Only ×Pyromeles was developed in 1988 from a cross between Chaenomeles japonica and Pyrus communis. This cross combination resulted in a seedling with intermediate morphological characteristics. The original seedling was propagated and preserved by grafting onto a quince rootstock but the grafted plants were characterized by stunted growth and a prolonged lack of flowering. Over the course of several decades, the putative hybrid did not advance to the generative phase and was at risk of extinction on multiple occasions due to accidental causes. In 2017–2018, the hybrid was grafted into the crown of pear and Swedish whitebeam trees. These six-year-old grafts flowered for the first time in 2024. The hybrid bloomed later, after the parent species had already finished flowering. The molecular methods were not used to identify the hybrid nature of this genotype, instead intermediate morphological features provided confirmation. Its flowers are of intermediate morphology, with pink petals like Japanese quince and purple anthers like pear, confirming the hybrid origin of the plant. Pollen is formed in the anthers and eggs are produced in the ovaries. One fruit was formed from the six inflorescences available, but it did not reach the ripening stage because it fell off prematurely. The cultivar ×Pyromeles ʻClaude Weberʼ has been described, which may be valuable as a bonsai due to its ornamental flowers and super dwarf habit.