1	"Fruit surfaces smooth; leaves equally green on both surfaces; plants of marshy to aquatic habitats"	"Datura ceratocaula"
1	"Fruit surfaces never completely smooth, usually with distinct spines; abaxial leaf surfaces usually paler than the adaxial; plants of mesic to dry habitats"	2
2	"Fruit pedicels erect; seeds without elaiosomes"	3
2	"Fruit pedicels recurved; seeds with elaiosomes"	5
3	"Fruit spines numerous, sometimes highly reduced, not markedly different in length, evenly distributed; interior unlobed portion of leaves ovate elliptic, width ??? Of length"	"Datura stramonium"
3	"Fruit spines fewer, the upper spines markely longer than those below (Datura ferox)"	4
4	"Unlobed interior of leaves broadly ovate; midveins not or sparsely hispid on lower surface"	"Datura ferox subsp. ferox"
4	"Unlobed interior of leaves narrowly ovate to elliptic; midveins densely hispid on lower surfaces"	"Datura ferox subsp. quercifolia"
5	"Outer margins of seeds triple-ridged,"	6
5	"Outer margins of seeds not triple-ridged"	10
6	"Seeds dark brown with smooth, shiny, depressed central area"	"Datura reburra"
6	"Seeds black, grey or light brown, without smooth, shiny depressed central area"	7
7	"Leaves glabrous; fruit spines short, blunt, sometimes reduced to bumps; corollas usually with two whorls and outer surfaces purple or yellows"	"Datura metel"
7	"Leaves pubescent; fruit spines never reduced, finely pointed; corollas with a single whorl, not purple on the outer surface"	8
8	"Corollas glabrous externally"	"Datura innoxia"
8	"Corollas pubescent externally"	9
9	"Leaf surfaces densely covered with short hairs, appearing grey; leaves smelling of peanut butter when rubbed"	"Datura wrightii"
9	"Leaf surfaces densely covered with fine long white hairs, appearing white; leaves not smelling of peanut butter"	"Datura lanosa"
10	"Seed coats verrucose"	"Datura kymatocarpa"
10	"Seed coats not verrucose"	11
11	"Fruiting calyces deflexed in fruit"	"Datura leichhardtii"
11	"Fruiting calyces reflexed in fruit"	12
12	"Corollas more than 8 cm long, their throats purple"	"Datura discolor"
12	"Corollas no more than 4 cm long, uniformly white to lavender"	"Datura arenicola"