This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Viscid-pubescent annual or perennial branching herbs, with entire leaves, and axillary or terminal solitary white violet or purple flowers (in cultivation sometimes variegated). Calyx deeply 5-cleft or 5-parted, the segments narrow. Corolla funnelform or salverform, the limb plicate, spreading, slightly irregular. Stamens 5, inserted on the throat of the corolla, 4 of them didy-namous, perfect, the fifth smaller or obsolete; filaments slender; anthers ovoid, 2-lobed. Disk fleshy. Ovary 2-celled; ovules numerous in each cavity; style filiform; stigma 2-lamel-late. Capsule 2-celled, 2-valved, the valves entire. Seeds small, the testa rugose. [Petun, an Indian name of tobacco.]
About 12 species, natives of South America. Type species: Petunia parviflora Juss. Corolla white, its tube cylindric.
1. P. axillaris.
Corolla violet-purple, its tube campanulate.
2. P. violacea.
Nicotiana axillaris Lam. Encycl. 4: 480. 1797. Petunia nyctaginiflora Juss. Ann. Mus. Paris, 2: 215.
pl. 47. f. 2. 1803. Petunia axillaris B.S.P. Prel. Cat. N. Y. 38. 1888.
Very viscid; stem stout, about 1° high. Leaves ovate to obovate, obtuse or blunt-pointed at the apex, sessile, or the lower narrowed into short margined petioles, 3'-4' long, 1-2' wide; peduncles slender, 2'~4' long, often longer than the leaves; calyx-segments linear-oblong, obtuse; corolla white, its tube cylindric, slightly enlarged above, 1'-1 1/2 long, 3-4 times as long as the calyx, its limb about 2' broad, the lobes rounded.
In waste places, escaped from gardens, southern New York and Pennsylvania. Native of Brazil. July-Sept.
Petunia violacea Lindl. Bot. Reg. pl. 1626. 1833.
Similar to the preceding species, but usually rather lower, and the stem slender. Leaves ovate or obovate, all but the uppermost petioled, mostly obtuse, \'-2\' long; peduncles slender, 1'-2' long; calyx-segments linear, subacute, or obtuse; corolla violet-purple, its tube campanulate, 9"-15" long, the limb less abruptly spreading, 1'-1 1/2' broad, the lobes subacute.
In waste places, escaped from gardens, southern New York and Pennsylvania. Native of southern Brazil and Paraguay. June-Sept.
Petunia parviflora Juss., a prostrate pubescent annual, with small linear to spatulate leaves, and a funnelform corolla 4"-5" long, has been found on ballast about the eastern seaports, from South America.