Chenopodium is a genus of numerous species of perennial or annual herbaceous flowering plants known as the goosefoots, which occur almost anywhere in the world.[2] It is placed in the family Amaranthaceae in the APG II system; older classification systems, notably the widely used Cronquist system, separate it and its relatives as Chenopodiaceae,[3] but this leaves the rest of the Amaranthaceae polyphyletic. However, among the Amaranthaceae, the genus Chenopodium is the namesake member of the subfamily Chenopodioideae.[1]
The species of Chenopodium (s.str., description according to Fuentes et al. 2012)[1] are annual or perennial herbs, shrubs or small trees.[4] They generally rely on alkaline soil.[4] They are nonaromatic, but sometimes fetid. The young stems and leaves are often densely covered by vesicular globose hairs, thus looking farinose. Characteristically, these trichomes persist, collapsing later and becoming cup-shaped. The branched stems grow erect, ascending, prostrate or scrambling. Lateral branches are alternate (the lowermost ones can be nearly opposite). The alternate or opposite leaves are petiolate. Their thin or slightly fleshy leaf blade is linear, rhombic or triangular-hastate, with entire or dentate or lobed margins.[1]
Inflorescences are standing terminal and lateral. They consist of spicately or paniculately arranged glomerules of flowers. Plants are monoecious (rarely dioecious). In monoecious plants flowers are dimorphic or pistillate. Flowers consist of (4–) 5 perianth segments connate, basally or close to the middle, usually membranous margined and with a roundish to keeled back; almost always 5 stamens, and one ovary with 2 stigmas.[1]
In fruit, perianth segments become sometimes coloured, but mostly keep unchanged, somewhat closing over or spreading from the fruit. The pericarp is membranous or sometimes succulent, adherent to or loosely covering the seed. The horizontally oriented seeds are depressed-globular to lenticular, with rounded to subacute margin. The black seed coat is almost smooth to finely striate, rugulose or pitted.[1]
The genus Chenopodium contains several plants of minor to moderate importance as food crops as leaf vegetables – used like the closely related spinach (Spinacia oleracea) and similar plants called quelite in Mexico – and pseudocereals.[citation needed] These include white goosefoot (C. album), kañiwa (C. pallidicaule) and quinoa (C. quinoa). On the Greek island of Crete, tender shoots and leaves of a species called krouvida (κρουβίδα) or psarovlito (ψαρόβλητο) are eaten by the locals, boiled or steamed.[citation needed] As studied by Bruce D. Smith, Kristen Gremillion and others, goosefoots have a history of culinary use dating back to 4000 BC or earlier, when pitseed goosefoot (C. berlandieri) was a staple crop in the Native American Eastern Agricultural Complex,[citation needed] and white goosefoot was apparently used by the Ertebølle culture of Europe.[citation needed] Members of the eastern Yamnaya culture also harvested white goosefoot as an apparent cereal substitute to round out an otherwise mostly meat and dairy diet c. 3500–2500 BC.[5]
There is increased interest in particular in goosefoot seeds today, which are suitable as part of a gluten-free diet.[citation needed] Quinoa oil, extracted from the seeds of C. quinoa, has similar properties, but is superior in quality, to corn oil.[citation needed] Oil of chenopodium is extracted from the seeds of epazote, which is not in this genus anymore.[citation needed] Shagreen leather was produced in the past using the small, hard goosefoot seeds.[citation needed] C. album was one of the main model organisms for the molecular biological study of chlorophyllase.[citation needed]