Attempts to resolve this have followed two opposing positions, lumping and splitting. Either accepting one artificial large catch-all polyphyletic genus, "sensu lato" ("Sedum s.l."), or splitting it into many smaller genera, "sensu stricto" ("Sedum s.l."). In the 1930s, Berger represented the splitting school of thought segregating genera such as "Orostachys", "Rosularia", "Pseudosedum" and "Sempervivella". In contrast, Fröderströmm favoured retaining a broader construct of "Sedum", recognising only "Pseudosedum". In more recent times Ohba (1978) proposed the narrower view, segregating "Rhodiola", "Hylotelephium" and "Prometheum", among other genera. Ohba then subdivided the old world taxa of his now reduced "Sedum" into five subgenera:   Grulich (1984) continued this process, proposing "Aizopsis" (subgenus "Aizoon"), "Asterosedum" (subgenus "Spathulata"), "Petrosedum" (subgenus "Sedum" series "Rupestria") and "Oreosedum" (subgenus "Sedum" series "Alba") as separate genera. As many as 32 segregate genera have been published, and most Eurasian crassulacean species were originally included in "Sedum", but subsequently segregated ("see" Sempervivoideae). Subsequently, various revisions have proposed fewer subfamilies. Takhtajan (1987) initially submerged Sempervivoideae in Sedoideae and Cotyledonoideae in Kalanchiodeae to produce four, but later (1997) only three, Crassuloideae, Kalanchoideae and Sedoideae. Thorne (1992) also proposed three (Sedoidea, Cotyledonoidea, Crassuloidea), and then two (2000), Crassuloideae and Sempervivoideae. Prior to the use of molecular methods of classification, attempts to replace Berger's system were largely unsuccessful. Subsequently, Hart and colleagues (1995) proposed two subfamilies, based on molecular phylogenetic data with chloroplast DNA, based on 49 species in 26 genera, which identified seven clades, named for constituent genera or species.