sentences:  The fastigiate cultivar ‘Erecta’, with bright yellow autumn colouring, has gained the Royal Horticultural Society’s Award of Garden Merit.The hybrid with "Populus alba" (white poplar), known as grey poplar, "Populus" × "canescens", is widely found in Europe and central Asia.Hybrids with several other aspens have also been bred at forestry research institutes in order to find trees with greater timber production and disease resistance (e.g.