Quercus × rehderi Trel.

This hybrid varies considerably between the very different parents but can be distinguished from Quercus velutina by its more shrubby habit and smaller leaves that are grey-tomentose beneath at least when young. Some forms can be close to Q. ilicifolia, but it can usually be distinguished from that species by the large leaves that lose a lot of the tomentum with age and the often more conspicuously divided and toothed upper lobes.

It was named by Trelease in 1917, presumably after Alfred Rehder, who found it in 1900 in the Blue Hill Reservation, Massachusetts (Rehder 1901). He described finding two trees, one 5 m high with a girth of 18 cm where the first branches appear and the smaller about 4 m high. He suspected they came from a common root and that they were secondary growth from a decayed stump. At the same location, he mentioned that the area was ‘almost exclusively covered by the low growth of Quercus ilicifolia, hardly exceeding 5 ft [1.5 m] in height.’

According to Palmer (1948), it is frequent where the parents grow together, and most specimens seen were shrubby but sometimes stouter and more tree-like than Q. ilicifolia.

According to Sargent (1922), the hybrid was introduced into cultivation by the Arnold Arboretum: a tree provided by Thomas Meehan and Son, Germantown, Pennsylvania, was accessioned in 1874 and had a dbh of 14.7 cm in 2020, while a second, from seed probably collected off this plant, was accessioned in 1895 and had a dbh of 11.2 cm (Arnold Arboretum 2025). Three plants at Arboretum des Pouyouleix, France, derive from seed collected at Martha’s Vineyard, Massachusetts, in 2015. One plant is listed at Arboretum de Passadou, France.