The rosids are members of a large clade (monophyletic group) of flowering plants, containing about 70,000 species,[2] more than a quarter of all angiosperms.

Molecular clock estimates indicate that the rosids may have originated in the Aptian or Albian stages of the Cretaceous, between 125 and 99.6 million years ago.

In 1967, Armen Takhtajan showed that the correct basis for the name "Rosidae" is a description of a group of plants published in 1830 by Friedrich Gottlieb Bartling.

[2][10] This is one of three groups that comprise the Pentapetalae (core eudicots minus Gunnerales),[11] the others being Dilleniales and the superasterids (Berberidopsidales, Caryophyllales, Santalales, and asterids).

[10] Vitales Zygophyllales Celastrales Malpighiales Oxalidales Fabales Rosales Fagales Cucurbitales Geraniales Myrtales Crossosomatales Picramniales Sapindales Huerteales Brassicales Malvales The nitrogen-fixing clade contains a high number of actinorhizal plants (which have root nodules containing nitrogen fixing bacteria, helping the plant grow in poor soils).