[Wikipedia] Identifcation: The best way to separate large bindweed from hedge bindweed (C. sepium) in flower is by the bracteoles, which subtend the flower and wholly or partially encompass the sepals. Large bindweed has short, wider bracteoles which overlap where they meet, whereas hedge bindweed has narrower, longer ones which leave a gap between them, allowing a glimpse of the sepals. Vegetatively, large bindweed can be distinguished from hedge bindweed by the shape of the sinus - the gap between the lobes at the base of the leaves. The former has a U-shaped sinus, in contrast to the usually V-shaped one in the latter. (link added by Mary Ann Machi)