1	"Leaves lobed, the lobes usually toothed or sinuate; capsule erect; seeds black or grey"	2
1	"Leaves entire to sinuate or lobed, the lobes entire; capsule deflexed; seeds brown or yellow"	3
2	"Flowers 6–10 cm long; capsule with more than 100 slender spines of various lengths, randomly distributed"	"Datura stramonium"
2	"Flowers 4.5–6 cm long; capsule with 40–60 stout spines, upper longer than lower"	"Datura ferox"
3	"Plants glabrous or sparsely pubescent with non-glandular hairs"	4
3	"Plants tomentose with non-glandular and/or glandular hairs"	5
4	"Branches green; flowers 4.5–7 cm long; capsule with numerous sharp spines"	"Datura leichhardtii"
4	"Branches tinged with purple; flowers 14–20 cm long; capsule with numerous short, blunt tubercles"	"Datura metel"
5	"Hairs glandular, erect; stigma well below level of anthers; margin of corolla limb angular"	"Datura inoxia"
5	"Hairs mostly non-glandular and retrorse, some glandular and erect; stigma usually exserted well above anthers; margin of corolla limb rounded"	"Datura wrightii"