Chenopodioideae

The Chenopodioideae are a subfamily of the flowering plant family Amaranthaceae in the APG III system, which is largely based on molecular phylogeny, but were included - together with other subfamilies - in family Chenopodiaceae in the Cronquist system. 
Food species comprise Spinach ("Spinacia oleracea"), Good King Henry ("Blitum bonus-henricus"), several "Chenopodium" species (Quinoa, Kañiwa, Fat Hen), Orache ("Atriplex spp."), and Epazote ("Dysphania ambrosioides").
Description.
The Chenopodioideae are annual or perennial herbs, subshrubs, shrub or small trees. The leaves are usually alternate and flat.
The flowers are often unisexual. Many species are monoecious or have mixed inflorescences of bisexual and unisexual flowers. Some species are dioecious, like "Spinacia", "Grayia", "Exomis", and "Atriplex". In several species of tribe Atripliceae, the female flowers are without perianth, but enclosed by two bracts. The species with a perianth have up to five tepals. The seed is horizontal or vertical, with annular or horseshoe-shaped embryo.
Distribution.
The subfamily Chenopodioideae is distributed worldwide, but originates from Eurasia.
Systematics.
The genera of this subfamily were formerly classified in family Chenopodiaceae in the Cronquist system.
According to Fuentes-Bazan et al. (2012) and based on molecular genetic research, the subfamily comprises 4 tribes and includes about 26 genera:
Fossil record.
The oldest fossil records for Chenopodioideae are pollen grains recovered from Maastrichtian sediments of the Edmonton Formation in Canada.