Solanum jamesii


Solanum jamesii distribution map
Solanum jamesii distribution map

Solanum jamesii, sometimes known as the “Four Corners potato,” is a wild potato of the United States and northern Mexico, with a couple of separate populations in central Mexico.  It is the only wild species with a distribution primarily in the United States, where it is found mostly in New Mexico and Arizona, but also reaches slightly into Colorado, Utah, and Texas at elevations above 5000 feet.  Plants are small, reaching about 6 to 15 inches in the wild, but taller under cultivation.  The specific epithet honors Edwin James, a US Army surgeon who first collected the species.

S. jamesii was (and still is to a small extent) used for food by native Americans, likely cultivated to some degree, and possibly even improved.  Louderback (2017) studied starch grains on ancient pottery and determined that this species was used as food in Utah as early as 8950 BC.  If it were used consistently over such a long period, it would be surprising if it had not been improved through selection, even inadvertently.  The primary pieces of evidence for its cultivation are (1) that populations are frequently found in close association with sites of previous human habitation; (2) that high levels of genetic diversity in some locations may indicate that plants were collected from other areas (Kinder 2017); and (3) that the tuber size and starch granule size of collections made near known archaeological sites are larger than those of collections not associated with such sites (Herzog 2018).  Bamberg (2016) reported that that majority of the genetic diversity present in the USDA collection of this species could be found in one site at Mesa Verde, suggesting the possibility that many different genotypes were brought together there by man.  According to Ortman (2018), although it later branched out to include other tuberous plants, the Tewa word sego refers specifically to Solanum jamesii, which must indicate that this was a plant of some importance prior to the introduction of other edible tubers that later were included under the same name.  This evidence is sometimes combined to support the thesis that S. jamesii is the earliest domesticated potato.  If it was improved, the differences between wild and relict cultivated populations are pretty small.  Overall, it seems like a stretch to describe this species as domesticated, but it makes for more attention grabbing headlines.  That may change though, as there are efforts underway to expand the use of this potato in native communities.

S. jamesii tubers are small, rarely reaching an inch in diameter and perhaps twice that for elite selections under cultivation.  With tubers from mixed accessions, I have found an average of 480 tubers per pound (1056 tubers per kg).  The tubers are usually white to tan, occasionally turning purple, apparently as a response to environmental conditions, as happens with many North American species.  Tubers can remain dormant for very long periods.  Bamberg (2010) found that tubers of many collections would store successfully at 41 degrees F (5 C) for eight years and recounted a story from a landowner who observed plants growing on resumption of irrigation after 39 years.  While 39 years seems unlikely, the upper limit for dormancy in S. jamesii remains unknown.

Kinder (2017) reported that wild collected tubers of S. jamesii had twice the protein content of S. tuberosum, along with substantial increases in potassium, calcium, magnesium, and other minerals.  These nutrient levels can probably be attributed primarily to the small size of the tubers.  In the domesticated potato, smaller tubers have a greater proportion of nutrient-rich skin and cortex to flesh and this probably holds true in all potato species.  Hale (2008) found that S. jamesii had high antioxidant activity.

Jarvis (2008) predicts that this species will lose 91% of its present range by 2055 due to climate change, most likely entailing a critical loss of genetic diversity.


This species can survive frosts down to 26 degrees F (-3.5 C) (Li 1977).  Vega (1995) found that this species is less frost tolerant than domesticated potato.  Johnson (1937) found that some tubers of this species were able to survive freezing for multiple days and Bamberg (2020) found that tubers could survive freezing down to 5 degrees F (-15 C) for as long as a week.

Pelletier (1999) found that Colorado potato beetles have increased adult and larval mortality and low egg production on this species.

At least one accession of this species carries a gene that confers resistance to the Chinese late blight strain (2013-18-306) that has cracked all S. demissum derived resistance genes (R1-R11) (Zheng 2020).

Condition Type Level of Resistance Source
Alternaria solani (Early Blight) Fungus Not resistant Jansky 2008
Cold Abiotic Resistant Bamberg 2020
Drought Abiotic Resistant Watanabe 2011
Globodera pallida (Pale Cyst Nematode) Invertebrate Resistant Castelli 2003
Globodera pallida (Pale Cyst Nematode) Invertebrate Not resistant Bachmann-Pfabe 2019
Globodera rostochiensis (Potato Cyst/Golden Nematode) Invertebrate Resistant Castelli 2003
Leptinotarsa decemlineata (Colorado Potato Beetle) Invertebrate Somewhat resistant Machida-Hirano 2015, Pelletier 1999
Meloidogyne spp. (Root Knot Nematode) Invertebrate Somewhat resistant Machida-Hirano 2015
Myzus persicae (Green Peach Aphid) Invertebrate Not resistant to moderately resistant Alvarez 2006
Pectobacterium carotovorum (Blackleg/Soft Rot) Bacteria Not resistant Chung 2011
Phytophthora infestans (Late Blight) Fungus Resistant Bhardwaj 2018
Phytophthora infestans (Late Blight) Fungus Resistant Bachmann-Pfabe 2019
Potato Leaf Roll Virus (PLRV) Virus Somewhat resistant Machida-Hirano 2015
Potato Virus A (PVA) Virus Moderate Webb 1961
Potato Virus X (PVX) Virus Moderate Webb 1961
Potato Virus Y (PVY) Virus Somewhat resistant Cai 2011
Streptomyces scabiei (Scab) Bacterium Immune Reddick 1939
Synchytrium endobioticum (Wart) Fungus Somewhat resistant Machida-Hirano 2015

Glykoalkaloid content

Gycoalkaloids in this species have been measured between 8.6 and 128 mg per 100 grams of fresh tuber.  Most of the published measurements fall into the lower part of the range (Johns 1990, Nzaramba 2009).  The generally accepted safety limit for potato glycoalkaloids is 20 mg / 100 g.  People can usually perceive bitterness at about 10 mg / 100 g.  The primary glycoalkaloid in this species is tomatine, unlike the domesticated potato, in which the primary glycoalkaloids are solanine and chaconine.  The normal expectation that bitterness is proportional to glycoalkaloid concentration may not hold with this species.  Johns (1986) reported that Aymara potato cultivators could not detect a significant flavor difference in tomatine solutions ranging from 40 to 80 mg / 100 ml, while they could easily detect differences in the same range of solanine and chaconine.  According to several sources, this species was traditionally eaten with clay or processed in some fashion and used dried (White 1944, Moerman 1998) in order to eliminate some of the glycoalkaloids.

If we assume that 128mg/100g is the upper limit for this species (which is certainly not a safe assumption), then a 150 pound person could probably eat about three ounces without experiencing symptoms of glycoalkaloid toxicity.  This is just an example and you should not consider it any kind of guidance for consuming this species.  There are no named cultivars and thus no way to know how the glycoalkaloid levels might vary from one plant to another.  It is possible that it is overly conservative to assume the same safe dosage for tomatine as for the more common potato glycoalkaloids solanine and chaconine.  Green tomatoes, which are a fairly common food, may contain anywhere from 50mg/100g to 500mg/100g of tomatine.  Although it hasn’t been studied in humans, this suggests that we may tolerate tomatine better than the more common potato glycoalkaloids.

Many people report eating this species without ill effect and I have done so myself, although I got a few plants with tubers that were noticeably bitter in 2018.  As with most potatoes that contain tomatine, I find that the tubers with (presumably) higher glycoalkaloids tend to taste more sour than bitter.  Overall, I think that S. jamesii is probably pretty safe, but we are working with a small amount of somewhat contradictory information, so it makes sense to proceed carefully until we know more.  The reports that S. jamesii was traditionally eaten with clay are a warning sign, regardless of what laboratory results say.


Aerial plant of the wild potato species Solanum jamesii
Solanum jamesii plant
Tubers of the wild potato species Solanum jamesii
Solanum jamesii tubers
Tubers of the wild potato species Solanum jamesii
Solanum jamesii tubers from a SE Utah accession
Tubers of the wild potato species Solanum jamesii
Solanum jamesii tubers from a Mesa Verde accession
Seedlings of the wild potato species Solanum jamesii
Solanum jamesii seedlings
Aerial plant of the wild potato species Solanum jamesii
Solanum jamesii plant
Aerial plant of the wild potato species Solanum jamesii
Solanum jamesii plant
Aerial plant of the wild potato species Solanum jamesii
Solanum jamesii plant
Tubers of the wild potato species Solanum jamesii
Solanum jamesii tubers
Emerging plant of the wild potato species Solanum jamesii
S. jamesii emerging foliage
Flower buds of the wild potato species Solanum jamesii
Solanum jamesii flower buds
Flowers of the wild potato species Solanum jamesii
Solanum jamesii flowers
Flowers of the wild potato species Solanum jamesii
Solanum jamesii flowers
Berries of the wild potato species Solanum jamesii
Solanum jamesii berries


Solanum jamesii grows in the high desert of the southwest United States and northern Mexico.  It is adapted to dry conditions, growing in sandy soils, with hot days and cold nights.  In the wild, S. jamesii usually sprouts during the rainy season in July and August (Kinder 2017).  Plants flower and fruit from June to October (Spooner 2004).  In cultivation, with irrigation, it can be started much earlier in the year, but I have found that flowering is poor here from an April sowing.  While the plants emerge and grow well, they produce few flowers.  In 2020, I planted in late June and the plants flowered more abundantly in our slightly warmer summer weather.

Tubers of this species have very long dormancy and that dormancy is not always easy to break.  Tubers sometimes do not sprout the same year that they are planted.  Planting into warm soil and keeping it well watered increases the probability of sprouting.  I recommend mixing tubers into an equal amount of damp potting soil in a plastic bag and leaving it in a warm place.  Plant the sprouted tubers.  This way, you will achieve a much more even stand than you would just planting dormant tubers.

I have found S. jamesii seeds easy to germinate, using the standard conditions for S. tuberosum.  Albino or chlorophyll deficient seedlings seem to be common in S. jamesii.  The albinos will die as seedlings and the variegated types are inferior and not worth keeping.  The USDA potato genebank has observed that germination of some accessions of this species is inhibited by gibberellic acid (Bamberg 1999).

Towill (1983) found that seeds of this species stored at 1 to 3 degrees C germinated at 38 to 94% after 15 years.

As with most wild potatoes, I recommend growing S. jamesii either in pots or in buried mesh bags to keep the stolons under control.  The tubers are small and form on long stolons, so harvest is a frustrating experience at best without some kind of containment.  It could easily spread and become difficult to eradicate.  Liter pots or bags work well for this species, although shallower and wider is better than deep and narrow containers.

I haven’t had much luck getting S. jamesii to flower in this climate, which is unusual, since virtually every other wild potato flowers well here.  Our spring and summer temperatures may be too cool for it.  So far, only about 1 in 20 plants have flowered and those only briefly.  Bamberg (1995) found that at least some accessions of S. jamesii flower better at high temperatures than under typical temperate growing conditions.  Flowering was better when greenhouse temperatures exceeded 100 degrees F for several hours during the day.  Pollen viability was also about the same regardless of temperature in several accessions, although markedly lower in others.

Trapero-Mozos (2018) determined that this species will tolerate a temperature of 40 C even without prior acclimatization to warm temperatures.

Accessions Evaluated

The following accessions were examined to prepare this profile.  I have evaluated 35/183 accessions currently available from the US Potato Genebank.

PI 275168

Colorado, Mesa Verde National Park, Navajo Canon, 1958.

PI 564052

Arizona, Apache County, Nelson Reservoir, 1992.

PI 564055

New Mexico, Catron County, Quemado, 1992.

PI 585117

New Mexico, Cibola County, Near Grants, 1992.

PI 585119

Colorado, Mesa Verde Nat. Monument at juct. Spruce and Navajo Canyons, 1994.

PI 592397

New Mexico, Near Albuquerque, just East of Tajique, 1995.

PI 592411

Arizona, Apache County, near Eagar, 1995.

PI 592416

Arizona, Apache County. Near Eagar, 1995.  Large plants noted.

PI 595783

New Mexico, San Miguel Co, 1996.  Large plants noted.

PI 603051

Utah, Garfield County. Escalante, 1997.

PI 603052

Utah, Garfield County. Escalante, 1997.

PI 603054

Colorado, Garfield County. Escalante, 1997.  Noted Anasazi site.

PI 603055

New Mexico, San Juan County. NE of Crownpoint. Chaco Culture National Historical Park, 1997.

PI 603057

New Mexico, San Juan County. NE of Crownpoint. Chaco Culture National Historical Park, 1997.

PI 605357

New Mexico, San Miguel Co. N of Pecos, 1998.

PI 605366

New Mexico, Cibola Co. Near Grants, 1998.

PI 605367

New Mexico, Catron Co. Near Pie Town, 1998.

PI 605369

New Mexico, Torrance Co. Near Tajique, 1998.

PI 612450

Colorado, Mesa Verde National Park. Junction of Spruce and Navajo canyons, 1998.

PI 612455

Arizona, Coconino County, 1999.  Large leaves noted.

PI 632324

Arizona, Navajo County. Sitgreaves National Forest, 2002.  Abundant fruit noted.

PI 632326

Arizona, Navajo County. Sitgreaves National Forest, 2002.  Large plants and abundant fruit noted.

PI 634364

Arizona, Mohave County. Fredonia area, 2003.  Large plants noted.

PI 641941

Utah, East of Escalante in the Escalante River Gorge, 2005.

PI 663210

Colorado, Mesa Verde. Navajo Canyon, 2011.

PI 664006

Arizona, Apache National Forest. Big Lue Mountains, 2011.  Large plants with fruit noted.

PI 664009

New Mexico, Gila National Forest. Mogollon Mountains, 2011.  Large plants with fruit noted.

PI 669594

Arizona, Apache National Forest. Near Eagar, 2013.  Large plants with fruit noted.

PI 673364

Arizona, Sitgreaves National Forest. Near Chevelon Creek, 2014.  Large plants with fruit noted.

PI 676014

Arizona, Coconino National Forest. Near Flagstaff, 2015.  Large plants with fruit noted.

PI 679921

Arizona, Sitgreaves National Forest. W of Eagar, 2016.  Large tubers noted.

PI 686446

New Mexico, Santa Fe National Forest. Near Glorieta, 2017.  Large plants noted.

PI 689409

Arizona, Navajo County, 2018. 

PI 689422

New Mexico, Catron Gila Cliff Dwellings. Gila National Forest, 2018.

PI 689425

New Mexico, Pinos Altos. Gila National Forest, 2018.  Large plants and large tubers noted.


As is true of most diploid potato species, S. jamesii is an outbreeder.  More than one clone is required to produce seed.

Crosses with S. tuberosum

There is a lot of interest in crossing S. jamesii with domesticated potatoes in order to introduce some of its interesting features like long dormancy to domesticated lines.  Unfortunately, it is very difficult to make crosses between this 1EBN species and either 2EBN or 4EBN domesticated potatoes.  The most likely way to get there is to cross S. jamesii with a 2EBN tetraploid species like S. acaule or S. stoloniferum, relying upon S. jamesii to produce unreduced gametes.  This would yield 2EBN tetraploid progeny.  The progeny could then be crossed to diploid domesticated potatoes, resulting in a triploid.  Triploids aren’t ideal, because they have limited potential for further breeding, but that doesn’t mean that they aren’t valuable on their own.  Progeny from this cross would be 1/3 domesticated and 2/3 wild genetics and, due to the likelihood of disomic segregation in the tetraploid parent, some of the progeny should be 2/3 S. jamesii genetics and 1/3 domesticated potato.

Another possibility would be to cross S. jamesii to S. verrucosum, a more closely related 2EBN diploid species.  S. verrucosum has shown some ability to cross successfully with S. jamesii, although the rate of success is low.  Despite the low rate, the progeny of such crosses are 2EBN diploids, providing the ability to cross directly to domesticated diploid potatoes, or to tetraploids through unreduced gametes.

Livermore (1940) attempted to make reciprocal crosses between tetraploid S. tuberosum and chromosome doubled S. jamesii without success.  This is consistent with what we know of S. jamesii.  It is a diploid species with 1 EBN.  After chromosome doubling, it would behave as a tetraploid with 2EBN.  Because S. tuberosum is tetraploid and 4 EBN, the cross is not compatible even after doubling.

Female Male Berry Set
Seed Set Germ Ploidy Source
S. jamesii S. tuberosum None None     Jackson (1999)
S. tuberosum S. jamesii None None     Jackson (1999)

Crosses with other species

The easiest crosses to make with S. jamesii will be those with other 1EBN diploids.  The problem is that most of those species have similar deficits to S. jamesii, namely small tubers and long stolons.  S. ehrenbergii and S. cardiophyllum (collectively known as cimatli), both have been through some light domestication and there are types with larger tubers.  It should be relatively easy to cross those with S. jamesii, but the question is what you would get in the bargain that those species don’t already have.

Matsubayashi (1977) examined chromosome pairing in hybrids and determined that S. x sambucinum and S. jamesii were highly compatible and likely closely related.  They found irregular chromosome pairing and reduced pollen fertility in crosses with S. bulbocastanum.

Watanabe (1991) found that 7.8% of varieties of this species produced 2n pollen and Jackson (1999) found 1-18%, which would be effectively tetraploid and 2EBN.

Female Male Berry Set
Seed Set Germ Ploidy Source
S. jamesii
S. bulbocastanum
Yes Yes   2x Matsubayashi 1977
S. jamesii S. commersonii Yes Yes     Reddick 1939
S. jamesii
S. polyadenium
Yes Yes     Magoon 1958
S. polyadenium
S. jamesii
Yes Yes     Magoon 1958
S. x sambucinum
S. jamesii
Yes Yes   2x Matsubayashi 1977


Solanum jamesii at Solanaceae Source

Solanum jamesii at GRIN Taxonomy

Solanum jamesii at CIP

Solanum jamesii at SEINet

2 thoughts on “Solanum jamesii

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    Robert says:

    Regarding toxicity of S. Jamesii., it grows in thisarea. The native people, and others, reccomend eating only newer immature tubers. Just put the old one back. It is much stronger.

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      bill says:

      Thanks Robert, that’s interesting information. That may help to account for the conflicting information about edibility with this species.

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