Flora of North America species comparison

Nicotiana tabacum is the principal tobacco of commerce and was the mainstay of the economy of the Chesapeake Bay region during Colonial times. It replaced N. rustica as the main cultivated species in North America in the early 1600s. Most herbarium specimens of N. tabacum come from gardens or research greenhouses, but it occasionally escapes and is an ephemeral weed where the climate is mild. Commercial tobacco cultivars are grown for their large leaves, and flowers are removed to allow further growth of top leaves before harvest, but if marginal individuals are not harvested and are collected, they could be mistaken for naturalized weeds. Nicotiana tabacum is widely cultivated across North America.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species ca. 75 (12 in the flora).

Nicotiana is recognizable by its tubular flowers and usually sticky pubescence. Of the species occurring in North America, only N. glauca is not sticky-pubescent. The genus has long been of interest due the high number of allopolyploid species (T. H. Goodspeed 1954; M. W. Chase et al. 2003; E. W. McCarthy et al. 2015).

Most species of Nicotiana in the flora area have distinct basal rosettes until flowering occurs, and cauline leaves usually differ in morphology from those in the basal rosette. Many species occur as short-lived perennials in areas without frost, but occur as annuals where winters are harder. The tree tobacco (N. glauca) is the only truly woody species occurring in North America.

Species of Nicotiana that bloom in the evening usually have white or cream flowers and are pollinated by moths, while day-flowering species have yellow, pink, or cream flowers and are pollinated by bees; however, this overall pattern does not hold strictly true. Nicotiana attenuata has become a model system for the study of the complex interplay between pollinators and herbivores in the evolution of floral and other traits (for example, C. Diezel et al. 2011; D. Kessler et al. 2015).

Nicotiana species are often cultivated and occur occasionally as garden or greenhouse escapes. Nicotiana alata Link & Otto and N. × sanderae W. Watson have been reported for the flora area but are known only as ephemerals or from cultivation. Some records of N. alata are possible misidentifications for N. longiflora, from which N. alata differs in its strongly decurrent cauline leaves and larger corollas with wider tubes. Nicotiana × sanderae has striking red salverform corollas; various horticultural hybrids of this long-flowered species are possible ephemeral occurrences on waste heaps.

The two tobaccos of commerce, Nicotiana rustica and N. tabacum, are cultivated as ornamentals or as sources of leaves for human use. Although most herbarium specimens from the flora area are clearly from cultivation, both taxa are sometimes adventive.

The small seeds and weedy habits of Nicotiana species predispose them to become invasive; for example, the non-native species N. glauca is a common component of ecosystems in western North America. This propensity to grow in disturbed areas means cultivated species are likely to become established briefly in areas where soil is loose or in old garden sites.

(Discussion copyrighted by Flora of North America; reprinted with permission.)