The two most common European species may form natural hybrids whenever they are sympatric (growing together). One, P. veris, is a central-to-east European/west Asian species with clusters of 10-30 nodding flowers on tall flower stalks, each flower not wider than 15 mm. The other, P. vulgaris, is from western and southern Europe, NW Africa, and SW Asia. It bears upright flowers of larger diameter, sized more like flowers in this photo, each on its own short stalk (flowers positioned at the same level as heavily wrinkled leaves). In hybrid plants, flower stalks are of intermediate height, bearing only a few flowers each (another intermediate character).