Cinquefoil

Potentilla /ˌpoʊtənˈtɪlə/ is a genus containing over 300 species of annual, biennial and perennial herbaceous flowering plants in the rose family, Rosaceae. They are usually called cinquefoils in English. Potentilla are generally only found throughout the northern continents of the world (holarctic), though some may even be found in montane biomes of the New Guinea Highlands. Several other cinquefoils formerly included here are now separated in distinct genera - notably the popular garden shrub P. fruticosa, now Dasiphora fruticosa. Some species are called tormentils, though this is often used specifically for common tormentil (P. erecta). Others are referred to as barren strawberries, which may also refer to P. sterilis in particular, or to the closely related but not congeneric Waldsteinia fragarioides. Typical cinquefoils look most similar to strawberries, but differ in usually having dry, inedible fruit (hence the name 'barren strawberry' for some species). Many cinquefoil species have palmate leaves. Some species have just three leaflets, while others have 15 or more leaflets arranged pinnately. The flowers are usually yellow, but may be white, pinkish or red. The accessory fruits are usually dry but may be fleshy and strawberry-like, while the actual seeds – each one technically a single fruit – are tiny nuts. Among the Rosaceae, cinquefoils are close relatives of avens (genus Geum) and roses (Rosa), and even closer relatives of agrimonies (Agrimonia). Yet more closely related to Potentilla are lady's mantles (Alchemilla) and strawberries (Fragaria). Dryas is not as closely related as long believed. Analysis of internal transcribed spacer DNA sequence data has yielded valuable information on cinquefoil relationships, supporting previous hypotheses about their relationships, but also resulting in a number of changes to the circumscription of Potentilla. The genera Horkelia (horkelias) and Ivesia (mousetails) are sometimes included in Potentilla today. The mock-strawberries of Duchesnea have been included. Conversely, the shrubby plants previously included in this genus are now separated in the genus Dasiphora, while some distinctive and apparently protocarnivorous herbaceous cinquefoils are placed in Drymocallis. The marsh cinquefoil is now in the genus Comarum, and the three-toothed cinquefoil makes up the monotypic genus Sibbaldiopsis. As already proposed by John Hill in the 18th century, the silverweeds of genus Argentina may be distinct, but as the immediate sister genus of Potentilla, its boundary is still unclear. Estimates of the number of valid species in this large genus depend on the circumscription used, and they recently vary from 'over 300' to 400 to 500 to 'several hundred'. See the list of Potentilla species.