Plants secrete a variety of substances from specialized structures called secretory structures—nectaries are the structures that secrete nectar, a sugary compound that attracts insects, birds, or other animals. Most nectaries are associated with flowers and are called floral nectaries. Nectar is 10 to 50 percent sugar, especially sucrose, glucose, and fructose. Plants usually produce small amounts of nectar, which forces foraging animals to visit several flowers before obtaining a full meal. A single insect or bird can, therefore, pollinate tens or hundreds of plants.