1	"Stems without glochids, not segmented (sometimes branching); seeds dark brown or black"	Echinopsis
1	"Stems with ""glochids"" (tiny barbed spines) in addition to normal spines; stems usually segmented; seeds with a hard pale bony covering (""aril"")"	2
2	"Stems distinctly flattened and pad-like, linear to linear-elliptic, oblanceolate to broadly obovate or orbicular"	Opuntia
2	"Stems cylindrical or rarely with some stems distinctly compressed, often flabellate with wavy margins"	3
3	"Stems of indefinite growth, branching laterally; spines without a papery sheath"	Austrocylindropuntia
3	"Stems segmented; spines covered with a loose or firmly attached papery covering forming a sheath"	Cylindropuntia