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Apios americana Medik.


Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Med and Vet Use
  5. Description
  6. Germplasm
  7. Distribution
  8. Ecology
  9. Cultivation
  10. Harvesting
  11. Yields and Economics
  12. Energy
  13. Biotic Factors
  14. References


Attractively-flowered plant suggestive of Wisteria, described by the NAS (1979) as a "useful, sweet-scented ornamental." I have enjoyed the tubers raw or cooked. During the potato famine of 1845, Apios was introduced to Europe. Its cultivation there as a food crop was abandoned when potato growing again became feasible. The plant was much esteemed by Early American Settlers who ate them boiled, fried, or roasted, calling them groundnuts, potato beans, or Indian potatoes. The Pilgrims of New England survived their first few winters by living on them. Krochmal and Krochmal (1974) give one recipe for the root and one for the beans. Erichsen-Brown (1979) recounts many of the Indian uses. Even bread was made from the root. Indians were said to eat the seeds like lentils. I would like to join the ranks of Ed Croom, Janet Seabrook, and Noel Vietmeyer and advocate more studies of the economic potential of this interesting tuber, harvestable all year round. Advocates should be aware of its weed potential, however.

Folk Medicine

According to Hartwell (1967–1971), the tubers were used in folk remedies for that cancerous condition known as "Proud Flesh" in New England. Nuts were boiled and made into a plaster, "For to eat out the proud flesh they (Indians) take a kind of earth nut boyled and stamped" (Hussey, 1976).


Some describe the plant as having a milky juice. Seabrook (1973) suggests that the latex could be used commercially. According to the NAS, the only published analysis (Yanovsky and Kingsbury, 1938) records a remarkable protein content of 17.5%. Duke, in an Appendix to the NAS book, mentions that 17.5 plus 57.1 g total carbohydrate and 4.7 g ash. Duke et al (1984) report more than 17% crude protein, 5% ash, 3.5% fat, and 73% total carbohydrate on a dry weight basis. At least 60% of the total N is protein. Tannin content (10.35 mg/g) and trypsin inhibitor activity (2228 units/g) are twice that reported for winged bean tubers. Saponins have been reported in the genus, and the absence of tannins (Gibbs, 1974), refuted above. Whether or not the plant exports its fixed nitrogen as ureides (allantoin, allantoic acid) as is typical of many of the subtropical Phaseoleae or as the more soluble amides (asparagine and glutamine) as in such temperate legumes as Lupinus, Pisum, Trifolium, and Vicia remains to be seen. Because it is suggested to have a cowpea type Rhizobium, I predict it will be a ureide exporter. Some calculations suggest it takes ca 2 1/2 times as much water (remember this is an aquaphyte) to export N as ureides. But the ureides are more economical with a C:N ratio ca 1:1 cf 1:1 for asparagine, 5:2 for glutamine (Sprent, 1981). Many legume sprouts are rich in allantoin, widely regarded as a vulnerary medicinal compound. According to the Merck Index, allantoin is a product of purine metabolism in animals, while it is prepared synthetically by the oxidation of uric acid with alkaline potassium permanganate

Med and Vet Use

Has been used topically in suppurating wounds, resistant ulcers, to stimulate growth of healthy tissue (Merck, 1968). Dorland's Illustrated Medical Dictionary puts it differently: allantoin (ah-lan'to-in) chemical name: 5-ureidohydantoin. A white crystallizable substance, C4H6N4O3, the diureide of glyoxylic acid, found in allantoic fluid, fetal urine, and many plants, and as a urinary excretion product of purine metabolism in most mammals but riot in man or the higher apes. It is produced synthetically by the oxidation of uric acid, and was once used to encourage epithelial formation in wounds and ulcers and in osteomyelitis. It is the active substance in maggot treatment, being secreted by the maggots as a product of purine metabolism. The direct role of allantoin in gout, if any, should be of great intereat to the 8% of American males who have gout, especially if they ingest large quantities of legume sprouts or comfrey. Apios produces a complex pterocarpan that appears structurally similar to glyceollin III, a phytoalexin of the cultivated soybean (Ingham, 1981).


Twining, herbaceous vine, the stems short-pubescent to glabrate, 1–3 a long. the roots moniliform, with numerous, fleshy tubers 1–8 cm thick. In winter the stems have a distinctive brown color and are locally flattened, enabling the experienced collector to distinguish it from honeysuckle. Leaves once-pinnate, 1–2 dm long; leaflets 5–7, ovate or ovate-lanceolate to lanceolate, ca 3–6 cm long, glabrous to short-pubescent, obscurely stipellate; petioles mostly 2–7 cm long; stipules setaceous, soon deciduous, 4–6 mm long. Inflorescence 5–15 cm long, nodes swollen, flowers 1–2 per node, subtended by linear-subulate bracts 2–2.5 mm long; pedicels 1–4 mm long with 2 linear-subulate bractlets near apex. Calyx sparsely short-pubescent, broadly campanulate, tube ca 3 mm long; petals brownish purple, the standard obovate or orbicular to obcordate, reflexed, obscurely auricled, 9–13 mm long, the wings shorter, alightly auricled, the keel strongly incurved; stamens diadelphous, 1 and 1. Legume linear, 5–12 cm long, 4–7 mm broad, 2-many seeded, dehiscing by 2 spirally twisted valves (Radford et al. 1968). Germination cryptocotylar (Seabrook, 1973).


Reported from the North American Center of Diversity, groundnut, or cvs thereof, is reported to coterate acid and bog soils, slopes, and waterlogging. In 1982, the Plant Introduction Officer of the USDA suggested to me the possibility of mounting a germplasm expedition to collect germplasm of this species, and its endangered relative, Apios priceana Robinson, which produces a single large tuber instead of a string of small tubers. NAS (1979) speculates that a bush-like mutant may be found in nature. Seedlings from Tennessee had 22 chromosomes, while plants from the northern part of the range were triploid. (2n = 22).


Widely distributed in eastern Canada and the US (often around ancient Indian campsites) (Florida, Texas, to Nova Scotia. Minnesota, and Colorado). Usually in low damp bottomland or riparian woods and thickets. Seems to be associated with Alnus in Rocky Gorge Reservoir, Maryland, as well as on the eastern shore of Maryland. Unfortunately, it can become a serious weed in cranberry plots (Devlin, pers. commun., 1981). Perhaps the cranberry sales men could find a market for the groundnuts, since both are Native American Food Plants.


Ranging from Subtropical Dry through Cool Temperate Forest Life Zones, groundnut is reported to tolerate annual precipitation of 9.7 to 11.7 dm (mean of 2 cases = 10.7), annual temperature of 9.9 to 20.3°C (mean of 2 cases = 15.1), and pH of 4.5 to 7.0 (mean of 2 cases = 5.8). Produces well in South Florida. I have successfully germinated fall harvested seed, after soaking in hot water, room temperature water, or frozen water, seeds that sunk and seeds that floated after soaking. These took four months to germinate while their unsoaked counterparts had still not germinated.


According to Vilmorin-Andrieux (1976), since seed do not ripen in France, it is multiplied by division in March and April, or in the latter part of summer. Divisions are planted in good, light, well-drained soil 1–1.5 m apart in every direction. Stems should be supported by poles or stakes. Ground should be kept free of weeds by an occasional hosing. Cultivation, if overdone, might discourage the runner roots and their tubers. Seedlings require at least two years growth and a minimum photoperiod of 14 hours to induce flowering (Seabrook, 1973). Tuber dormancy can be broken by chilling or using ethylene.


According to Vilmorin-Andrieux (1976), the tubers are not large enough to be gathered for use until the second or third year after planting. Once large enough, they can be dug at any time of the year when the ground is not frozen. If carefully dug, strings of four score tubers can be achieved.

Yields and Economics

According to Elliott (1976), Asa Gray once said that if advanced civilization had started in North America instead of the Old World, the groundnut would have been the first tuber to be developed and cultivated. Fernald et al. (1958) recount an anecdote indicating the economic value of the groundnuts to the pilgrims, "The great value to the colonists of this ready food is further indicated by a reputed town law, which in 1654 ordered that, if an Indian dug Groundnuts on English land, he was to be set in stocks, and for a second offence, to be whipped." Duke et al (1984) report tuber yields from cranberry bogs approaching 30 MT/ha.


Currently, this looks like a poor prospect for biomass production. However, one should at least consider the possibility of developing the crop for marginal habitat (swamp), the tubers as the main crop, the aerial biomass, as residue, might be used for production of rubber, leaf protein, and power alcohol. The nodulated roots fix nitrogen. Around Rocky Gorge Reservoir, in Maryland, the plant is most commonly intertwined in N-fixing Alnus species. Nodules were recorded on A. americana but root-nodule location relative to tuber formation was not specified. Root hairs are said to be lacking on secondary roots of mature plants. Four rhizobial strains isolated from A. americana nodules were not tested on the host, but since they produced nodules on cowpea plants, the species was considered a member of the cowpea miscellany. The rhizobia are described as monotrichously flagellated rods with cowpea-type, slow cultural growth (Allen and Allen, 1981). Duke et al (1984) cite a personal communication suggesting conservatively, that the Apios fixes >100 kg N/ha. With no idea of the solubility of N fixed by the groundnut, I recommend it be studied as a potential intercrop for marsh and aquatic plants, especially rice and wild rice. It might also be considered for cultivation around the edges of reservoirs used for irrigation, hence adding a small token of nitrogen to the irrigation waters. Because of their tolerance to both acidity and waterlogging, they might be especially advantageous around impoundments in stripmine reclamations. Certainly the scoring by Roth et al (1982) do not speak well for the energy potential of Apios. They give it a score of 14, in a system whereby only species receiving scores of 11 or less were regarded as potential renewable energy sources.

Biotic Factors

Agriculture Handbook No. 165 lists the following diseases affecting this species: Alternaria sp. (leaf spot), Cercospora tuberosa (leaf spot), Erysiphe polygoni (powdery mildew), Microsphaera diffusa, Phymatotrichum omnivorum, and Puccinia andropogonis var. onobrychidis (rust). Although most Erythrinae are bird pollinated, Apios seems to be mostly bee pollinated (Kalin Arroyo, 1981).


Complete list of references for Duke, Handbook of Energy Crops
Last update December 29, 1997