1	"Shrub, small tree; herbage glabrous, glaucous"	"Nicotiana glauca"
1	"Annual, perennial herb; herbage generally glandular-hairy"	2
2	"Corolla 50--75 mm; cauline leaves generally elliptic; basal leaf petioles winged"	"Nicotiana sylvestris"
2	"Corolla 15--50(65) mm; cauline leaves generally lanceolate; basal leaf petioles winged or not"	3
3	"Upper cauline leaves clasping; perennial herb, base often +- woody; corolla open during day"	"Nicotiana obtusifolia"
3	"Upper cauline leaves not clasping; annual; corolla generally +- closed during day"	4
4	"Cauline leaves generally +- sessile (except lowest)"	5
4	"Cauline leaves petioled"	6
5	"Corolla tube 15--20 mm, limb 8--10 mm wide; stamens attached +- at 1 level below tube middle; calyx lobes very unequal"	"Nicotiana clevelandii"
5	"Corolla tube 25--50 mm, limb 20--50 mm wide; stamens attached at various levels generally above tube middle; calyx lobes +- unequal"	"Nicotiana quadrivalvis"
6	"Calyx dark-striped, lobes narrowly lanceolate, unequal, generally +- >= tube, not pock-marked; plant densely glandular-hairy"	"Nicotiana acuminata var. multiflora"
6	"Calyx not striped, lobes triangular, +- equal, < tube, pock-marked; plant glabrous to +- sparsely glandular-hairy"	"Nicotiana attenuata"