Chenopodium berlandieri, also known by the common names pitseed goosefoot,[1] lamb's quarters (or lambsquarters), and huauzontle (Nahuatl) is an annual herbaceous plant in the family Amaranthaceae.

[2] The fast-growing, upright plant can reach heights of more than 3 m. It can be differentiated from most of the other members of its large genus by its honeycomb-pitted seeds, and further separated by its serrated, evenly lobed (more or less) lower leaves.

[3] Although widely regarded as a weed, this species was once one of several plants cultivated by Native Americans in prehistoric North America as part of the Eastern Agricultural Complex.

[6] The lenticular shape is more typical of wild members of the species while cylindrical seeds (said to have a "truncated margin") predominate in domesticated varieties.

Cupping the flower is a green calyx with 5 lobes 0.5 to 1.5 mm long and variable shape: triangular or egg-shaped, strongly keeled, blunt to rounded at the tip and thin and papery around the edges.

The tips may be pointed or blunt, while wedge-shaped or straight across at the base tapering to a stalk up to 3+1⁄2 inches (89 mm) long.

Lower leaves are largest, irregularly toothed, 1+1⁄2 to 2+ times as long as wide and usually with a pair of shallow lobes near the base.

[18][19] Archaeological evidence shows the species was extensively foraged as a wild plant in eastern North America as early as 6,500 BC.

[13] The oldest evidence for domestication comes from caches of thin-testa seeds from rock shelters in the Ozark Plateaus and Ohio River basin.

[6] According to Le Page, the Natchez people cultivated a grain-like crop called Choupichoul that was delicious, nutritious, highly productive, and required minimal human labor.

[6] Chenopodium berlandieri was cultivated alongside three other starchy, seed-bearing plants, namely maygrass, little barley and knotweed, providing an important nutritional basis for indigenous groups at the time.

[25] These qualities may explain why indigenous people kept cultivating Chenopodium berlandieri despite the large effort of harvesting its minuscule seeds.

When exposed to full sun conditions, the plants tend to be robust with many lateral branches producing high quantities of seed.

Plants growing in shaded conditions tend to be more gracile, taller, with fewer lateral branches and produce less seed.

Although occurring in vast numbers, seed size makes collecting enough for daily or long-term subsistence needs of an individual or group challenging.

[25] The yield of pitseed goosefoot can vary substantially due to the differences in amount of sunlight received by the plants.

[20] Members of the Chenopodium species have been implicated among the greatest weed threats to agriculture in North America and globally.

[34] This success can be attributed to their ability to survive across a range of environmental conditions due to a high reproductive capacity, variation in their dormancy and germination requirements, and abiotic stress tolerance.

[34] Most research identifies European species C. album as a prime candidate for resistance to multiple herbicides, in particular to triazines and glyphosates.

The weed status and herbicide tolerance of C. berlandieri is less researched and less clear due to its many wild and semi-domesticated forms resulting from frequent hybridization and polyploidy.

[39] This cross-compatibility and hybridization leads to the formation of crop-weed complexes, between C. berlandieri plants as well as with other members of the Chenopodium species.

This may be due to a recent Western bias against weedy plants, as well as a manifestation of colonial history which led to a disconnect from the local environment and indigenous knowledge.

[45] Another method involves chemical processing, whereby gradual, controlled heating of the seeds detoxifies them, allowing nutrients to be bioavailable for digestion.

[20] People with gout, arthritis, rheumatism, kidney stones, or hyperacidity should use caution when consuming the plant, as it may aggravate their condition.

[45] As with other Amaranthacae species, Chenopodium berlandieri is rich in macronutrients of proteins, carbohydrates and fats, as well as micronutrients including vitamins and minerals.

[47] They have shown significant contents of protein, inorganic nutrients of Calcium (Ca), Iron (Fe) and Magnesium (Mg).

[47] It also has a high percentage of oleic, linoleic and linolenic acids, which are essential for human nutrition,[48] and highest total flavonoids index (TFI) when compared to other Amaranthacae species.

[45] Studies have shown that some saponins may form insoluble complexes with minerals, such as zinc and iron, thus negatively affecting absorption and bioavailability of nutrients in the gut.

[46] Saponins are bitter, but break down during the cooking process, rendering them harmless and allowing nutrients to be bioavailable to humans.

C. berlandieri shares some qualities with its medicinally useful relatives such as Chenopodium ambrosioides which is a widely known vermifuge and a potential food preservative.