Forms of Fruit

The fruits of different species of plants exhibit a variety of forms, and fruit form is a valuable trait in classifying plants. The wall of a ripened ovary is called the pericarp. The pericarp may consist of two or three layers: the exocarp, mesocarp, and endocarp. A berry has a fleshy pericarp with a thin skin. Examples of berries are grapes, tomatoes, peppers, and blueberries. A drupe is a single-seeded fruit having a stony endocarp (that is, a pit). Examples of drupes are cherries, peaches, and olives. A legume derives from a single carpel and splits along two lines. Examples of legumes are beans and peas. A follicle is similar to a legume but splits along one line. An example is milkweed. An achene is a small fruit having a single seed and a hard pericarp. Buckwheat and dandelion are two examples. The list of fruit characteristics goes on, and those who study taxonomic botany make much use of fruit characteristics in the course of classification, see figure 36-1.