1	"Perennial soft-wooded shrub or small tree to 6 m high; corolla yellow"	"Nicotiana glauca"
1	"Annual or short-lived perennial herb to 3 m high; corolla white or pink"	2
2	"Plant 1–3 m high; filaments of all stamens inserted near base of corolla-tube; inflorescence short, dense, panicle-like; corolla white or pink"	3
2	"Plant usually less than 1 m high; filaments of 4 stamens inserted near summit of corolla-tube; inflorescence elongated, loose, panicle- or raceme-like, or flowers solitary in axils; corolla white"	4
3	"Leaves radical and cauline, upper ones subsessile to sessile; corolla white, trumpet- shaped; corolla-tube 65–85 mm long"	"Nicotiana sylvestris"
3	"Leaves nearly all cauline, upper ones shortly petiolate; corolla white to pink, funnel- shaped; corolla-tube 30–55 mm long"	"Nicotiana tabacum"
4	"Plant pubescent or velvety with soft woolly hairs on all parts"	"Nicotiana velutina"
4	"Plant glabrous or almost so (more or less glandular-hairy on flowers and sometimes sparsely hairy on lower stems)"	5
5	"Corolla-tube less than 20 mm long, less than 3 mm wide at apex of calyx, limb less than 12 mm diam.; seeds C-shaped"	"Nicotiana goodspeedii"
5	"Corolla-tube 20–55 mm long, mostly 3–5 mm wide at apex of calyx, limb 14–35 mm diam.; seeds reniform or angled"	"Nicotiana suaveolens"