Chenopodium


Chenopodium is a genus of numerous species of perennial or annual herbaceous flowering plants known as the goosefoot, which occur almost anywhere in the world. 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, but this leaves the rest of the Amaranthaceae polyphyletic. However, among the Amaranthaceae, the genus Chenopodium is the namesake member of the subfamily Chenopodioideae.

Description

The species of Chenopodium are annual or perennial herbs, shrubs or small trees. They generally rely on alkaline soil. 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 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.
Inflorescences are standing terminal and lateral. They consist of spicately or paniculately arranged glomerules of flowers. Plants are monoecious. In monoecious plants flowers are dimorphic or pistillate. Flowers consist of 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.
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.

Taxonomy

The genus Chenopodium was described by Carl Linnaeus in 1753. Type species is Chenopodium album. This generic name is derived from the particular shape of the leaf, which is similar to a goose's foot: from Greek χήν, "goose" and πούς, "foot" or , "little foot".
In its traditional circumscription, Chenopodium comprised about 170 species. Phylogenetic research revealed, that the genus was highly polyphyletic and did not reflect how species were naturally related. Therefore, a new classification was necessary. Mosyakin & Clemants separated the glandular species as genus Dysphania and Teloxys in tribe Dysphanieae. Fuentes-Bazan et al. separated many species to genera Blitum, Chenopodiastrum, Lipandra, and Oxybasis. They included Rhagodia and Einadia in Chenopodium.

Species

132 species are currently accepted.
Certain species grow in large thickets, providing cover for small animals. Goosefoot foliage is used as food by the caterpillars of certain Lepidoptera. The seeds are eaten by many birds, such as the yellowhammer of Europe or the white-winged fairy-wren of Australia. Goosefoot pathogens include the positive-sense ssRNA virusesapple stem grooving virus, sowbane mosaic virus and tobacco necrosis virus.

Uses

The genus Chenopodium contains several plants of minor to moderate importance as food crops as leaf vegetables - used like the closely related spinach and similar plants called quelite in Mexicoand pseudocereals. These include white goosefoot, kañiwa and quinoa. On the Greek island of Crete, tender shoots and leaves of a species called krouvida or psarovlito are eaten by the locals, boiled or steamed. 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 was a staple crop in the Native American Eastern Agricultural Complex, and when white goosefoot was apparently used by the Ertebølle culture of Europe. Members of the eastern European 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.
There is increased interest in particular in goosefoot seeds today, which are suitable as part of a gluten-free diet. Quinoa oil, extracted from the seeds of C. quinoa, has similar properties, but is superior in quality, to corn oil. Oil of chenopodium is extracted from the seeds of epazote, which is not in this genus anymore. Shagreen leather was produced in the past using the small, hard goosefoot seeds. C. album was one of the main model organisms for the molecular biological study of chlorophyllase.
Goosefoot pollen, in particular of the widespread and usually abundant C. album, is an allergen to many people and a common cause of hay fever. The same species, as well as some others, have seeds which are able to persist for years in the soil seed bank. Many goosefoot species are thus significant weeds, and some have become invasive species.
According to the 1889 book The Useful Native Plants of Australia, the species Chenopodium auricomum is "another of the salt-bushes, which, besides being invaluable food for stock, can be eaten by man. All plants of the Natural Order Chenopodiaceae are more or less useful in this respect." The book goes on to give the following account from the Journal de la Ferme et des Maisons de campagne:
We have recently gathered an abundant harvest of leaves from two or three plants growing in our garden. These leaves were put into boiling water to blanch them, and they were then cooked as an ordinary dish of spinach, with this difference in favour of the new plant, that there was no occasion to take away the threads which are so disagreeable in chicory, sorrel, and ordinary spinach. We partook of this dish with relish—the flavour—analogous to spinach, had something in it more refined, less grassy in taste. The cultivation is easy: sow the seed in April in a well-manured bed, for the plant is greedy; water it. The leaves may be gathered from the time the plant attains 50 centimetres in height. They grow up again quickly. In less than eight days afterwards another gathering may take place, and so on to the end of the year.

Safety

occur in the leaves, stem, pith and mesophloem.

Fossil record

†Chenopodium wetzleri fossil seeds of the Chattian stage, Oligocene, are known from the Oberleichtersbach Formation in the Rhön Mountains, central Germany.