The species includes two subspecies: the type subspecies (i.e. Chenopodium berlandieri ssp. berlandieri) and Chenopodium berlandieri ssp. nuttalliae. The latter, which also goes by the common names huauzontle, huauthili and Nuttall's goosefoot, is a domesticated line still in cultivation in Mexico, and is distinguished by a substantial reduction in testa thickness.
The type species includes the following varieties:
C. b. ssp. berlandieri var. berlandieri
C. b. ssp. berlandieri var. boscianum
C. b. ssp. berlandieri var. bushianum (Bush's goosefoot)
C. b. ssp. berlandieri var. macrocalycium
C. b. ssp. berlandieri var. sinuatum
C. b. ssp. berlandieri var. zschackii (Zschack's goosefoot)
Additionally, there are three important cultivars of the nuttalliae subspecies:
'Huauzontle' - This cultivar is a more recent selection used in commercial cultivation for a broccoli-like crop. It is a "naked" variety and has a testa only 2-7 µm thick (cf. human hair, which is about 100 µm wide).
'Chia' - Grown as a grain crop, this cultivar is declining and is only cultivated on a local level. It also has a very thin testa, though slightly thicker than the previous at 10-20 µm.
'Quelite' - This cultivar is also grown only locally and is likewise in decline. It is cultivated for its spinach-like leaves.
The species is capable of hybridizing with the related introduced European Chenopodium album, which it resembles, giving the hybrid C. × variabile Aellen.
Chenopodium berlandieri, also known by the common names pigweed, pitseed goosefoot, huauzontle, and lambsquarters, is an annual herbaceous plant in the goosefoot family.
The species is widespread in North America, where it is native to Alaska and northern Canada south to Michoacán, Mexico, and including every U.S. State except Hawaii. 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 serrate, more or less evenly lobed lower leaves.
Although widely regarded today as a weed, this species was once part of the Eastern Agricultural Complex of prehistoric North America, and was a fully domesticated pseudocereal crop, similar to the closely related quinoa C. quinoa. It continues to be cultivated in Mexico as a pseudocereal, as a leaf vegetable, and for its broccoli-like flowering shoots.
Chenopodium berlandieri is one of the few plants that was domesticated in the prehistoric and Woodland period in eastern North America, making it a part of the so-called Eastern Agricultural Complex. There is archaeological evidence that shows that Chenopodium berlandieri was extensively foraged as a wild plant in eastern North America as early as 8,500 BP (6,500 BCE). By 3700 BP (1700 BCE) the plant had clearly been domesticated as a pseudocereal crop. A variety of regional cultivars have even been recovered from various widely separated sites. The oldest evidence for domestication comes in the form of stashes of thin-testa seeds from rock shelters in eastern Kentucky. The crop ceased to be cultivated in the region by about 1750 CE.
Although cultivation of the species died out in eastern North America, the plant continues to be grown as a domesticated crop in Mexico, though its cultivation has been declining. This cultivated form of the plant is ranked as a subspecies, namely Chenopodium berlandieri ssp. nuttalliae. There are three varieties of the subspecies which are grown as a pseudocereal, as a leaf vegetable, and for its broccoli-like flowering shoots, respectively.
Based on similarities between this modern cultivated form and the archaeological specimens from eastern North America, it was suggested that the species was first domesticated in Mexico and later brought to upper North America. There is currently no archaeological evidence to support this position, with some experts even suggesting that the crop may have been absent from Mexico until the 16th century CE. Genetic studies have shown that wild eastern North American plants and the Mexican cultivated forms have considerable genetic distance between them. This has been interpreted as indicating a later second domestication event in Mexico.[