3. Nicotiana tabacum L. (tobacco)

Map 2620

Plants annual (biennial or short-lived perennial elsewhere), sometimes taprooted. Stems 100–250 cm long, stout, densely pubescent with a mixture of shorter and longer, woolly or matted to mostly spreading, multicellular, gland-tipped hairs. Leaves numerous above the often persistent basal rosettes and only gradually reduced toward the stem tip (the stems appearing densely leafy), the lowermost leaves sometimes with short, winged petioles, the other stem leaves sessile, the bases expanded and decurrent along the stem for a short distance below the attachment point. Leaf blades (8–)12–50 cm long, lanceolate or oblanceolate to elliptic or ovate; the margins entire to slightly wavy, relatively flat, the surfaces sparsely to densely pubescent with short, mostly gland-tipped hairs, more densely so along the veins, usually also with sessile glands. Inflorescences short to more commonly elongate or somewhat pyramidal panicles, mostly with numerous flowers. Calyces 12–20 mm long, faintly 5-ribbed, glandular-hairy, the tube longer than the 5, triangular lobes, these tapered to sharply pointed tips. Corollas 5–6 cm long, glandular-hairy, the tube funnelform (the tubular base expanded abruptly above the midpoint), white, often greenish-tinged toward the base and pinkish- or reddish-tinged toward the tip, the lobes 5–8 mm long, triangular to broadly triangular, pink or red, rarely white. Fruits 15–20 mm long, ellipsoid to ovoid, oblong-obovoid, broadly ovoid, or nearly globose. Seeds 0.4–0.6 mm in longest dimension, the surface with a network of ridges, brown to dark brown. 2n=48. July–October.

Introduced, uncommon, known thus far only from a single historical collection from St. Louis County (native of South America, introduced sporadically in the U.S.; Canada). Habitat unknown, but presumably open disturbed areas.

Tobacco is among the most controversial of crop plants in the United States. Originally cultivated in Andean South America, the species is an example of the ancient exchange of goods between South American and North American cultures, having become widely cultivated in the North America during pre-Columbian times (Heiser, 1969). Early Spanish and English explorers in North America were quick to notice this plant, which was used medicinally for a number of ailments and also ceremonially by the peoples they encountered. During the 1600s, tobacco became an important export item from the Colonies to Europe, and over time its cultivation proliferated as European expansion pushed westward on the North American continent. Because tobacco cultivation is a labor-intensive practice, the industry became closely associated with slavery prior to the American Civil War. During the first half of the nineteenth century, tobacco was a major crop plant in Missouri, but the industry began a long decline following the Civil War. Today, a few farms continue to produce slightly more than 1,700 tons of dried leaves annually, down from more than 3.3 million tons in 1902 (W. Williams, 1904). The history of Missouri’s tobacco industry is interpreted at Weston Bend State Park (Platte County).

Tobacco is grown primarily for its leaves, which are harvested and then cured through drying. The leaves contain thousands of biochemically active compounds (National Cancer Institute, 1998), but the mild sedative and euphoric effect is caused primarily by nicotine, a highly addictive alkaloid. The fermented and dried, ground leaves most frequently are burned and the smoke inhaled through smoking in cigars, cigarettes, and pipes. They are also taken orally by allowing the juice to diffuse from a small amount inserted into the mouth (between cheek and gum). To a lesser extent, the finely ground leaves also have been inhaled directly as snuff. Tobacco is a controlled substance in the United States, a legal drug whose production and distribution are heavily regulated and taxed by federal and state governments. Ingestion of tobacco is considered very unhealthy (with direct causal links established to various cancers [especially lung cancer] and leukemia). Since the early 1960s, the federal government has invested heavily in attempts to educate Americans about the evils of tobacco products. Although this has led to a decline in the sales of cigarettes, it has not made the desired impact on the public demand for tobacco products. Smokers also should note that nicotine and its biosynthetic derivatives are an important ingredient in some poisons used as insecticides.