SOLAN ACE^ 597 



stamens attached to the corolla tube; the filaments are slen- 

 der, and the anthers split lengthwise. The two-celled ovary 

 bears a single, slender style, and a capitate stigma. 



Fruit. — The fruit is a two-celled capsule bearing numerous 

 very small seeds ; it splits into two or four valves at maturity. 



Geographical Distribution and Economic Importance. — 

 The genus includes about 50 species, mostly of the American 

 tropics. A number of species are grown for ornamental pur- 

 poses. N. tabacum (tobacco) is the only one of great commer- 

 cial importance. 



NICOTIANA TABACUM (Tobacco) 



Habit, Roots, Stems. — The common tobacco is a strong 

 annual plant, 3 to 5 feet tall. The root system is quite ex- 

 tensive and fibrous. The American varieties bear large, 

 thick stems which are hairy and sticky. In tobacco culture 

 it is customary to "top" the plants, that is, remove the 

 flower stalks, so that a considerable portion of the food supply 

 which would normally go to flower and fruit production may 

 be directed to leaf growth. Topping stimulates the produc- 

 tion of "suckers" (new shoots). They must be removed 

 before reaching any great size, as the quality of the leaves is 

 damaged by their growth. The "one-sucker" type of 

 tobacco is one that throws out one or only a few suckers. 



Leaves." — There is great variation in the shape, color, tex- 

 ture, and number of leaves. In cigar-wrapper tobaccos, the 

 leaves are thin, fine in texture, and small-veined. The 

 leaves of plug and pipe tobaccos are usually coarser, thicker, 

 and tougher. The leaves are sessile, decurrent, and either 

 narrow or broad, most commonly lanceolate or ovate, and 

 pointed. The number of leaves on a plant, which is, of 

 course, important commercially, is different in the various 

 types and also varies considerably from plant to plant in the 



