Chenopodium berlandieri

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. 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. 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: • '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 oldest evidence for domestication comes from caches of thin-testa seeds from rock shelters in the Ozark Plateaus and Ohio River basin. Multiple lines of evidence suggest that the crop was a domesticated variety of C. berlandieri. 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. Indigenous people used pitseed goosefoot not only for subsistence, but also for medicinal and preservative reasons. 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. 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. == 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. 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. For example, following the spread of C. quinoa across North America as a novel crop, one study found that up to 30% of wild C. berlandieri grown along the periphery of quinoa fields were crop/weed hybrids. Gene flow was observed to be asymmetric (from crop to weed), due to a preferential flow of pollen from high-density populations of domesticated C. quinoa to dispersed populations of wild C. berlandieri. This directional crop-weed interaction has implications for the future of introgressive change in wild C. berlandieri varieties. While genetic introgression is often degenerative for both crops and wild plants, it may also promote greater biodiversity in conventional cropping systems and present research opportunities for new crop varieties. == Cultivation ==

Climate & soil requirements Chenopodium berlandieri is an extremely versatile plant; it can handle a variety of elevations, commonly found growing at sea level and at elevation, such as in the San Juan mountains of Colorado. In the Andes of South America, there are varieties of lambsquarter that grow at over . It is very cold hardy and therefore one of the later weeds to be killed by frost. It dislikes shade. 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. Chenopodium berlandieri thrives in many types of soil with varying pH levels. When the soil is fertile, it will grow large and full in size and form very attractive stands of vegetation. The presence of a stand of healthy lambsquarter is one of the best indicators for vital soil. However, it can also handle the worst of soils and has been known to even survive in disturbed soils such as annual vegetable gardens, neglected fields and coal-pit heaps. Like its close relatives, it can serve as a cover crop and natural fertilizer because of its dense nutrient content. The seeds themselves can stay dormant for many years and take root when the conditions are ideal. The species is hermaphroditic, having both male and female organs on the same plant, which are wind-pollinated. It is known to cross-pollinate with Chenopodium album to create a hybrid. The plant is in flower from July to October, with green-hued flowers. From August to October, the seeds ripen. == Nutrition ==

As with other Amaranthaceae species, C. berlandieri is rich in macronutrients of proteins, carbohydrates and fats, as well as micronutrients including vitamins and minerals. Its high nutritional quality has given rise to researching its use for food security in rural populations. The leaf nutritional content, expressed per 100 g of fresh weight: 0.2 kJ Fat, 3.45 kJ Protein, 3.17 kJ total dietary fiber (primarily insoluble fiber; 8.3% to 12.8% of the recommended daily intake), 111.8 kJ energy, 2.21 kJ available carbohydrates. and highest total flavonoids index (TFI) when compared to other Amaranthacae species. In the plant, the saponin quantity is too small to harm humans. 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. Saponins are bitter, but break down during the cooking process, rendering them harmless and allowing nutrients to be bioavailable to humans. Cooking also reduces the oxalic acid content, which may also raise concerns. == Uses ==

Chenopodium berlandieri has little presence in the current world food system, especially compared to other plants within its genus, such as Chenopodium quinoa or C. ambrosioides. 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. Tests for and analyses of bioactive chemical compounds would likely resolve questions about the use of Chenopodium berlandieri and the medicinal use may be evident in the concentration of these compounds. ==See also==