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Nicotiana (tobacco; family Solanaceae) A genus of annual and perennial herbs whose leaves are of varying shape, without stipules. The flowers are regular and composed of 5 sepals and 5 petals fused to form a tube. The stamens are attached to the corolla, the ovary is superior with 2 fused carpels and 1 style. The fruit is a berry with seeds containing a copious endosperm. N. tabacum is the cultivated tobacco. Many species contain the highly toxic alkaloid nicotine, which is a powerful insecticide. Some species are cultivated for their bright flowers. There are 67 species, and the genus is represented in Australia, the south Pacific, subtropical regions of N. and S. America, and in south-western Africa.