Chenopodium berlandieri, also known by the common names pitseed goosefoot, lamb's quarters (or lambsquarters), and huauzontle (Nahuatl), is an annual herbaceous plant in the family Amaranthaceae.
The species is widespread in North America, where its range extends from Canada south to Michoacán, Mexico. It is found in 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 serrated, evenly lobed (more or less) lower leaves.
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. C. berlandieri was a 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.
Description
Leaves and stems The leaves are alternate, long and up to wide. The leaves are variable in shape: diamond to triangular to egg-shaped to lance-elliptic in outline. The tips may be pointed or blunt, while wedge-shaped or straight across at the base tapering to a stalk up to long. The lower leaves are largest, irregularly toothed, to 2 or more times as long as wide and usually with a pair of shallow lobes near the base. Leaves become smaller and less toothy as they ascend the stem with the uppermost leaves often much narrower, proportionately longer and toothless.
Surfaces are green, hairless and moderately to densely white-mealy, especially when young. The upper surface usually becomes smooth, while the lower surface usually remains white-mealy. Stems are also highly variable: erect to ascending, unbranched to much branched and sparsely to densely white-mealy, especially on the upper stem. The stem color may vary from green to purple-striped to red.
Flowers Very small flowers are tightly packed in small round clusters (glomerules) in spike-like and branching arrangements at the top of the stem, at the tips of branching stems and arising from upper leaf axils. The glomerules usually crowd on the branch. Within a glomerule, flowers may be at different stages of development: some just budding and others with maturing fruit. Flowers lack petals, have 5 stamens and a round, green ovary with a 2-parted style at the tip that is not divided all the way to the base. 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. Bracts are leaf-like or sometimes absent. The calyx, stalks and branches are moderately to densely white-mealy.
Seeds
Chenopodium seeds vary in shape between lenticular and cylindrical. 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.
The nutritive perisperm tissue is encircled by the embryo along the seed margin. The radicle protrudes slightly, producing a visible bump in the circumference of the seed (called the "beak"). Surrounding the perisperm and embryo are three layers: the inner epiderm, the outer epiderm, and the pericarp. The inner epiderm is also called a tegmen. The outer epiderm is synonymous with testa. Together, the outer and inner epiderm make up the seed coat. In Chenopodium literature, the terms outer epiderm, testa, and seed coat are often used interchangeably.
The pericarp is often dehiscent, but is non-dehiscent in some varieties. In domesticated varieties, the seed coat may be reduced or absent. Uniform seed assemblages with seed coats less than 20 μm thick are considered to represent domesticated population. Conversely, wild populations tend to produce seeds with seed coat thicker than 20 μm.
Taxonomy The species includes two subspecies: the type subspecies (i.e. C. b. ssp. berlandieri) and C. b. ssp. nuttalliae. The latter, which also goes by the common names huauzontle, huauthili and Nuttall's goosefoot, is a domesticated variety cultivated in Mexico.
As many as six extant varieties of C. b. ssp. berlandieri have been identified: C. b. subsp. berlandieri var. berlandieri C. b. subsp. berlandieri var. boscianum C. b. subsp. berlandieri var. bushianum (Bush's goosefoot) C. b. subsp. berlandieri var. macrocalycium C. b. subsp. berlandieri var. sinuatum C. b. subsp. berlandieri var. zschackii (Zschack's goosefoot) The extinct variety is well-documented, though it may represent more than one taxon: C. b. subsp. jonesianum Additionally, the cultivars of the C. b. nuttalliae subspecies are: '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 cultivated only 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 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.
Domestication C. berlandieri is the progenitor of all domesticated Chenopodium varieties in North and South America. In prehistoric eastern North America it was a part of the Eastern Agricultural Complex, a set of cultivated and domesticated species which supported sedentary and migrant populations for thousands of years. Archaeological evidence shows the species was extensively foraged as a wild plant in eastern North America as early as 6,500 BC. By 1700 BC, the plant had clearly been domesticated as a pseudocereal crop. The name given to the domesticated variety is C. b. ssp. jonesianum. The oldest evidence for domestication comes from caches of thin-testa seeds from rock shelters in the Ozark Plateaus and Ohio River basin. The only known potential historic record of C. b. ssp. jonesianum is a ca. 1720 account by Antoine Simon Le Page du Pratz. 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. Multiple lines of evidence suggest that the crop was a domesticated variety of C. berlandieri.
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.Smith, Bruce D. (1987). The economic potential of Chenopodium Berlandieri in prehistoric Eastern North America. J. Ethnobiol. 7(1):29-54. https://ethnobiology.org/sites/default/files/pdfs/JoE/7-1/Smith1987.pdf Around approximately 1600 BC, another annual starchy seed crop, maize, appeared in the Eastern Woodlands. Maize would later on come to dominate much of North American agriculture, but for about 3000 years, maize formed only a minor component of garden or field plots. By approximately 1150 AD, maize became a major dietary constituent of prehistoric populations in the Eastern Woodlands. This led to a substantial decrease in Chenopodium berlandieri cultivation. Nonetheless, pitseed goosefoot remained important up until the point of European contact, after which it virtually disappeared.
Indigenous people used pitseed goosefoot not only for subsistence, but also for medicinal and preservative reasons. Chenopodium berlandieri prevents intestinal parasites and has the capacity of preserving foods. These qualities may explain why indigenous people kept cultivating Chenopodium berlandieri despite the large effort of harvesting its minuscule seeds.Robinson, Daniel Shelton, " Chenopodium berlandieri and the Cultural Origins of Agriculture in the Eastern Woodlands. " Master's Thesis, University of Tennessee, 2012. https://trace.tennessee.edu/utk_gradthes/1198 It is the raw leaves that were used medicinally, rather than the seeds.
Although cultivation disappeared in eastern North America, C. b. subsp. nuttalliae continues to be cultivated as a domesticated crop in Mexico. Three varieties of the subspecies are grown as a pseudocereal, as a leaf vegetable, and for its broccoli-like flowering shoots, respectively.
The principal difference between wild and domesticated forms of Chenopodium is the thickness of the seed coat. In the domesticated varieties, due to selective pressures during domestication, the testas are less than 20 microns thick; the testas of wild chenopods are 40 to 60 microns thick.Smith, Bruce D. (1995), The Emergence of Agriculture, New York: Scientific American Library, p. 184 This morphological characteristic is shared by the modern cultivated chenopod C. b. subsp. nuttalliae and the archaeological specimens of C. b. ssp. jonesianum. Genetic studies have shown that eastern North American and Mexican cultivated forms have considerable genetic distance between them. Despite the initial assumption of a single domestication event, consensus in the field now supports at least two independent domestication events in North America. Similarly, C. berlandieri's South American branch likely experienced at least two independent domestication events, both of which are called C. quinoa.
Weed status Members of the Chenopodium species have been implicated among the greatest weed threats to agriculture in North America and globally. 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.
Importantly, the Amaranthaceae family is one of five weed families (along with Poaceae, Asteraceae, Brassicaceae, and Chenopodiaceae) that represent only 50% of the world's principal weeds but account for approximately 70% of all cases of herbicide resistance. 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.
The spread and sporadic domestication of C. berlandieri across eastern North and Central America has resulted in a complex network of domesticated and wild sub-species known to co-exist and interact in shared ecosystems. Human paleofeces collected from Salts Cave in Kentucky and Big Bone Cave in Tennessee were found to contain both seeds from weed and crop forms of the plant seemingly consumed within hours of each other, suggesting close spatial proximity and a potential for hybridization between populations.
Morphological studies identified that seeds from weedy varieties of C. berlandieri tend to have a thicker testa (seed coat), a more rounded or biconvex margin configuration, more prominent testa patterning, a less developed beak, and a smaller overall size when compared to their domesticated counterparts. However, intermediate morphologies were also identified, indicating genetic interaction (crossing over) between these groups.