Echinopsis sensu latiore (Friedrich, 1974), including Echinopsis Zucc., Trichocereus Ricc., Helianthocereus Backbg., Pseudolobivia Backbg. p.p., Soehrensia Backbg. and Hymenorebutia Fric ex Buin., can be divided by seed characters into a limited number of sub-generic units. 48 SEM photos show representative seeds of group Ia = large northern Trichocerei, group Ib = Chilean Trichocerei, group IIa = southern Trichocerei including Helianthocereus and Soehrensia, group IIb = E. terscheckii and the ‘Pasacanas’, group IIIa = Echinopsis sensu stricto and Pseudolobivia pro parte, group IIIb = E. leucantha and F. chacoana, group IVa = E. aurea and related species, group IVb = Hymenorebutia. Chamaecereus silvestrii is attached here as group IVc (Echinopsis chamaecereus nom.nov.). Useful seed characters for this grouping were the size and the outline of the seed, the form and position of the hilum, the shape and size of testa cells and the microsculptural patterns of the testa caused by cuticular pleatings. Apart from nine new combinations, formal taxonomic changes, though suggested, are postponed until a monographic treatment brings additional facts.