Nicotiana tabacum, or cultivated tobacco, is an annually-grown herbaceous plant.
It is found in cultivation, where it is the most commonly grown of all plants in the genus Nicotiana, and its leaves are commercially grown in many countries to be processed into tobacco.
It grows to heights between 1 and 2 meters. Research is ongoing into its ancestry among wild Nicotiana species, but it is believed to be a hybrid of Nicotiana sylvestris, Nicotiana tomentosiformis, and possibly Nicotiana otophora.
he plant is native to the Caribbean, where the Arawak/Taino people were the first to use it and cultivate it. In 1560, Jean Nicot de Villemain, then French ambassador to Portugal, brought tobacco seeds and leaves as a “wonder drug” to the French court.
Nicotiana tabacum Linné is a robust annual branched herb up to 2.5 m (8.2 ft) tall, with large green leaves and long, trumpet-shaped, white-pinkish flowers. All parts of the plant are sticky, being covered with short viscid-glandular hairs which exude a yellow secretion containing nicotine.
Tobacco leaf surface under an optical microscope, magnification 100x:
2. Epidermal cells
Varied in size, the lower leaves are the largest at up to 60 cm (24 in) long, short-stalked or unstalked, oblonged-elliptic, shortly acuminate at the apex, decurrent at the base, the following leaves decrease in size, the upper one sessile and smallest, oblong- lanceolate or elliptic.
In terminal, many flowered inflorescences, the tube 5–6 cm (2.0–2.4 in) long, 5 mm (0.20 in) in diameter, expanded in the lower third (calyx) and upper third (throat), lobes broadly triangular, white-pinkish with pale violet or carmine colored tips tube yellowish white; calyx with five narrowly triangular lobes which are 1.5–2 cm (0.59–0.79 in) long. A capsular ovoid or ellipsoid, surrounded by the persistent calyx and with a short apical beak, about 2 cm (0.79 in) long. Seeds are very numerous, very small, ovoid or kidney shaped, brown.
Almost every part of the plant except the seed contains nicotine, but the concentration is related to different factors such as species, type of land, culture and weather conditions. The concentration of nicotine increases with the age of the plant. Tobacco leaves contain 2 to 8% nicotine combined as malate or citrate. The distribution of the nicotine in the mature plant is widely variable: 64% of the total nicotine exists in the leaves, 18% in the stem, 13% in the root, and 5% in the flowers.[citation need