American tobacco belongs almost exclusively to that group of this family which comprise the genus _Nicotiana_. Of this genus there are about 50 separate species, one of which, _Nicotiana Tabacum_, supplies almost all the tobacco of commerce. Plants of this species grow from 2 feet to 9 feet in height; they have numerous wide-spreading leaves sometimes as much as 3 feet in length; these leaves may be oval, oblong, pointed, or lanceolate in shape, and are generally of a pale green color when young; they are arranged alternately in a spiral on the stem; the root is large and fibrous; the stem is erect, round and viscid, branching near the top. The alternate arrangement of the leaves on the stalk, succeeding each other spirally, so that the 9th overhangs the 1st, the 10th the 2nd, and so on, is very characteristic. The distance on the stalk between the leaves is about 2 inches. Flowers are in large clusters, with corollas of rose color, or white tinged with pink. The leaves and stalks are covered with soft downy hair. The plant is perennial but crops are usually raised from seed. Of this species (N. Tabacum) there are probably more than 100 varieties grown in the U. S. alone. Some of the best known will be described later. To this same species (N. Tabacum) Havana, East Indian and European tobaccos principally belong. The other important species are: _Nicotiana Persica._ Grown in Persia. This has a white flower and the leaves almost enwrap the stem. It is used almost exclusively as a pipe-smoking tobacco. Some claim that this is only a variant of N. Tabacum. _Nicotiana Repanda._ This is a species of Cuban tobacco entirely different from that grown in the Havana district. It is also called Yara. _Nicotiana Rustica._ A kind of wild growing tobacco principally cultivated in Mexico, and which is claimed as the parent of some of the Turkish, Syrian and Latakia tobaccos although many authorities claim that these tobaccos belong to the species _N. Tabacum_. The European tobacco is hardier than the American parent plant. The leaves are smaller. _N. Rustica._ Also includes common Hungarian and Turkish tobaccos. There are large and small leaved varieties. _N. Crispa._ Grown in Syria and largely in Central Asia. Used as a cigarette tobacco in the Orient. It has been stated above that there are many varieties of _N. Tabacum_ in the U. S. Of these the most important are known to botanists by the names, _Nicotiana Tabacum Macrophylla_ and _Nicotiana Tabacum Angustifolia_. Maryland tobacco belongs to the _Macrophylla_ variety and there are many other types differing from each other according to shape of the leaf, size of the stalk, etc. Virginian tobacco is of the _Angustifolia_ variety, and of this also there are many different types. Most European and other grown tobaccos have been raised from original plants of the Maryland and Virginian varieties.