Berries are classified as drupes, true berries, epignyous fruits, compound fruits and poisonous fruits, according to LoveToKnow. Drupes and epignyous fruits don't meet the classic definition of berries, but these fruits are referred to as such by mistake. True berries meet the technical definition of berries and are defined as fruits that are produced from a single ovary. Compound fruits are berries that contain multiple seeds.
Love To Know further notes that compound fruits include strawberries, blackberries and raspberries. Drupes are fleshy fruits with small stones and include acai berries, sugarberries and hackberries. Grapes, barberries and elderberries are fruits that are considered true berries. Citrus fruits are known as modified berries or juicy berries. Some epignyous fruits are blueberries, juniper berries and cranberries. Cranberries and blueberries are classified as false berries, because these fruits are produced from the ovary and different parts of flowers. Strawberries and raspberries form from different flower parts and fall under aggregate fruits or drupes.
Poisonous berries can comprise different fruit types. Mistletoe berries are poisonous and are normally found on mistletoe. Holly berries are bright red and grow on holly plants. Yew berries are bright red with a green stone comprising the core and normally grow on evergreen shrubs. Jerusalem cherries are berries that take on the appearance of cherry tomatoes. Red and green nightshade berries grow on weed-like plants. Elderberries spawn vibrant, red berries that are poisonous, but the purple ones can be used for cooking and medicinal purposes. However, the leaves and stems of purple elderberries are poisonous. Certain poisonous berries spawn mild symptoms, such as stomach complications, but others are potent enough to kill.