What species of tobacco is primarily used for smoking and chewing products?

The species primarily used for smoking and chewing products is Nicotiana tabacum. This plant has been cultivated for centuries and is the most important source of tobacco products around the world. Nicotiana tabacum contains higher concentrations of nicotine compared to other species of tobacco, making it particularly popular for its psychoactive effects. Its leaves are processed and manufactured into various products, including cigarettes, cigars, and chewing tobacco.

The other species, while related to tobacco, are not commonly used in commercial tobacco products. For instance, Nicotiana rustica, known as Aztec tobacco, has been used historically but doesn't have the same level of commercial production as Nicotiana tabacum. Nicotiana glauca, often referred to as tree tobacco, contains nicotine but is not utilized for mainstream tobacco products due to its different chemical makeup and characteristics. Nicotiana benthamiana is primarily used in research and as a model organism in genetic studies, rather than for any tobacco products. Thus, the prominence of Nicotiana tabacum in the tobacco industry clearly establishes it as the primary species for smoking and chewing products.