Crataegus flava, summer haw, yellow-fruited thorn is a very rare species of hawthorn that was long known in cultivation in England but apparently is no longer grown. Unfortunately, due to an error by Sargent the name C. flava was, and often still is, used for a different species C. lacrimata, which belongs to a different series, the Lacrimatae. Series Flavae is another group of species that were thought to be related to the misidentified C. flava, and although it is now apparent that they are not related, the name of the group remains. Because the true identity of this species has only recently been discovered, the name is rarely used correctly.