Complex sentence: Variegated English Elm has been in commerce since the 18th century, and remains so in the UK, "U. procera"'Argenteo-Variegata', RHS, rhs.org.uk/plants/nurseries-search-result ?
Split into simpler sentences: Variegated English Elm has been in commerce since the 18th century. The tree remains in cultivation in the UK, "U. procera"'Argenteo-Variegata', RHS, rhs.org.uk/plants/nurseries-search-result?