Misc. Tuberous Legumes
Pachyrihzus aphia
Pachyrihzus aphia is a tuberous legume found in the same genus as jicama. Originally grown in South America, this plant is cultivated by Native Americans in the area, though the practice is less common now. This plants' root is often eaten fresh and contains a high amount of vitamin C and carbohydrates (starch/sugar). The tuber is normally turned into juice during the festival of Todos Santos. The tuber is also used to make gluten-free flour, is often added as a thickener like starch, or used in a traditional southern dish called sari. Root starch theoretically could also be used to make biodegradable plastics.
The seeds of P. aphia have a high protein content and oils similar to soybean. They do contain rotenone, a toxin, which is why the seeds are not used for feed or food.
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Like most legumes, Pachyrihzus aphia can fix nitrogen via symbiosis with bacteria, forming nodules that develop spherically and then branch off.
Reference: Rodrigues-Navarro, Dulce; Marten Osrensen, Eduardo Leide. Ahipa, Pachyrhizus ahipa: a legume with edible tuberous roots
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Pediomelum esculetum
Pediomelum esculetum, also known as "prairie turnip", is a nitrogen-fixing herbaceous perennial native to the Great Plains of North America. A fun fact about this plant is it hosts a nitrogen fixing endophyte (Bracillus spp.) that is passed vertically through generations!
The taproots of prairie turnip normally take 2-4 years to mature and the root has a thin inedible bark that must be removed prior to consumption. The tuber can be roasted, boiled, or dried and ground into a flour. The flour can be used in recipes like America Indian frybread which is what makes the bread extra light and fluffy.
Reference: Stai, Jacob. Ethnography of prairie turnip, Pediomelum esculentum
Pueraria spp.
The genus Pueraira includes many woody lianas (like kudzu) that originate from Asia. Some of the plants in this genus can produce large tubers up to 400 lbs! The uses of tubers range from food to medicine, soil remediation and enrichment, and more.
P. tuberosa comes from the Himalayans and is used as food or in ayurvedic medicine as a rejuvenating tonic to help with inflammation, diuretic conditions, and other aliments. It can also be used as a contraceptive.
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P. candollei var. mirifica hails from Thailand where it is known for its rejuvenating abilities to aid menopausal or andropausal women and men. The roots are dried, powdered, then mixed with honey to form pills which are claimed to restore menstruation and hair loss, improve sleep, promote appetite, and other cures. These reactions are likely due to phytoestrogens~ phytoesterols, isoflavnoids, coumenstans, where are all found in the tuber.
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P. lobate, more commonly known as Kudzu, originates near China, Korea, and Japan where it was gathered at used for “food, fodder, fiber, paper, and medicine”. Tubers are dried to from a Ge Gen powder, or kuzo-ko tea, used to treat spasms and aid in circulation, help reduce fevers, headaches, and stiffness in the neck along with many other ailments. The tubers are also cooked or turned into flour. The flour is often used in Japan as a thickening agent. Kudzu is a nitrogen fixer and was initially planted in the United States as a cover crop to help enrich soils, until it’s fast growth turned it into an invasive species that is now banned in many space. However, it does have some redeeming qualities like a potential biofuel that's similar to corn.
Reference: Egan, Ashley. Economic and ethnobotanical uses of tubers in the genus Pueraria DC
Vigna subterranea
Vigna subterranea or bambara groundnut is native to sub-Saharan Africa where it is grown as a grain legume whose seeds are eaten fresh or ground into flour or fed to livestock. It does not produce a tuber, but is an important legume in local agro-ecosystems and is vital in helping local communities with food security.
Reference: Silue, Napkalo; Yay Toure, Sergio Ochatt, Mongomake Kone. In vitro culture of Bambara groundnut [Vigna subterranea (L.) Verdc.]: State of the Art