A complex hybrid with red foliage in spring and summer (Molnar 2011).
USDA Hardiness Zone 4
RHS Hardiness Rating H7
In the years from 1968, Harry Lagerstedt at Oregon State University experimented with hybridising clones of Corylus × colurnoides with fruiting hazels of European origin, in the search for a non-suckering commercial rootstock. He also had the idea of incorporating the genes for red leaf colour, so that any sprouts from below the graft would be easy to spot. Corylus ‘Ruby’ was released in 1990 as a by-product of this breeding programme: a controlled hybrid of C. × colurnoides ‘Gellatly 4’ with a plant grown as C. avellana ‘Fuscorubra’; the young leaves of ‘Ruby’ retained their reddish-purple colour for longer in summer than earlier red-leaved fruiting selections (Molnar 2011).
‘Ruby’ was quickly superseded as an ornamental purple hazel with good hardiness and some resistance to Eastern Filbert Blight by another Oregon State University complex hybrid, Corylus ‘Rosita’ (q.v.), whose habit is neater and more compact (Smith & Mehlenbacher 2002).