 Compounding the problem is that apomixis is common in several genera.This results in an uncertainty in the number of species contained in each of these genera, due to the difficulty of dividing apomictic complexes into species.For example, "Cotoneaster" contains between 70 and 300 species, "Rosa" around 100 (including the taxonomically complex dog roses), "Sorbus" 100 to 200 species, "Crataegus" between 200 and 1,000, "Alchemilla" around 300 species, "Potentilla" roughly 500, and "Rubus" hundreds, or possibly even thousands of species.