Variable hybrids between M. baccata and M. prunifolia. Leaves pubescent beneath, at least at first; pedicels slender; calyx usually glabrous, sometimes persisting, sometimes not; petals white or pinkish; fruit subglobose to ellipsoid, to 2 cm diameter, red or yellow, slender-stalked (Rehder fide Fiala 1994).
RHS Hardiness Rating H6
Conservation status Not evaluated (NE)
Showy in autumn with their long-persisting fruit, hybrid Siberian crabs have been in cultivation far longer than they have been recognized as a distinct hybrid group. They seem to have arisen in East Asia. One form (‘Bigg’s Everlasting Crab’) was raised from Siberian seed at Cambridge Botanic Garden in 1816; ‘Red Siberian’ and ‘Yellow Siberian’ were grown in Europe by the second half of the 19th century (Rehder 1920; Jefferson 1970; Bean 1981). There were further introductions in the early decades of the 20th century by Wilson, Sargent and Purdom, from the Beijing area and Japan (Arnold Arboretum 2020; Fiala 1994). Rehder (1920) brought these together under M. × robusta, based on their inferred parentage, something which seems to have been accepted without question thereafter. Nevertheless, the name M. × robusta on its own is almost never seen on plants, rather as a portmanteau for named cultivars, notably ‘Dolgo’ (see ‘Cultivars D-F’) and ‘Red Sentinel’ (see ‘Cultivars R’). Even then, concrete evidence for their belonging here rather than being more complex hybrids is lacking; ‘Dolgo’, for example, is said to have been a seedling from M. × robusta.