These plants have often been treated as a small-seeded variety of scandens that tends to occur in drier habitats: fruiting perianth 4-7 mm (versus 7-10 mm), with wings 1-1.7 mm wide (versus 1.5-3 mm) and more or less undulate (versus more or less flat); see F, FNA 5, Y and W. Horton (1972) indicated that the variation may be continuous, and further study is needed in the field, garden and herbarium. Kim et al. (2000) have recommended variety status for cristata, but their morphological analysis showed clear separation from scandens. It is notable that these plants often occur in subxeric acid woods with chestnut oak, while typical scandens occurs mostly in fertile lowland woods. F. Levy (pers. comm.) has found similar segregation in ne. Tenn. F. dumetorum (L.) Holub, in its strict sense, is an alien from Eurasia that has often been confused with cristata and reported from Ky. (B, M, FNA 5); but no verified colls. have been seen. See also notes under convolvulus.