Jícama: A Toxic Plant with Tasty Roots

Pachyrhizus erosus (L.) Urb.

Jícama with Cactus: photo by Sophia Healey (2021).

Do you find it odd that there is a giant bulbous tuber— that belongs to an otherwise toxic tropical plant —being offered for dirt cheap in most big-box grocery stores in America?

We are talking about a root commonly referred to by an ancient Nahuatl name, jícama. It is most commonly pronounced as HICK-em-uh, or he-CAH-mah. Thankfully, due to the musicality of language, there will never be a definitively “correct” colloquial pronunciation.

I’ll divert you briefly down the alley of digression:

Isn’t it beautiful that the Nahuatl term far easier to say than the clonky English moniker, “yam bean tuber?” The later exudes all of the grace and poetry of a drunken farmer falling down a staircase.

Back to business:

The jícama tuber is substantially larger than your average softball, making it not only a root vegetable, but a minor commitment. When you peel the fibrous (and toxic [8]) brown rind from the outside of the tuber, you expose a crispy-wet white flesh that is slightly sweet when crunched on raw. If this intrigues you, you may be left to wonder: “what the heck do I do with the rest of this thing?”.

Well, Traveller, we have searched the world for answers, and we come bearing gifts. Welcome to the bulbous and bodacious world of an ancient New World bean tuber. Welcome to the world of Pachyrhizus erosus.

Jícama!

Image created by Forest Starr and Kim Starr are licensed under a Creative Commons Attribution 3.0 License, permitting sharing, adaptation, and commercial use with attribution.

Family — Fabaceae

Family Characteristics —  Fabaceae family members have flowers with a classic “banner, wing, and keel” morphology and tend to fix atmospheric nitrogen.

Aliases —  Mexican turnip, Mexican water chestnut, potato bean, yam bean, yam bean tuber; sar-gott, 豆薯 (CHINA); sinkama (FILIPINO); dolique bulbeuse (FRENCH); bengkuang (INDONESIAN); chicam, štšikam, tšikam, xicam (MAYA); jícama (NAHUATL); củ đậu {meaning: bean root}, củ sắn (VIETNAM);

Binomial Etymology —Pachy- is derived from GREEK and is used to connote thickness, or the word thick; -rhizus, also derived from GREEK, refers to the the plant’s root; erosus, is a derived reference to the GREEK god of love, EROS [1]. You may know this god by the name, CUPID, from the Roman pantheon.

I have a sneaking suspicion that this “thick root of love” might have some reputed aphrodisiac effects so I prepared some for my beautiful wife. Only time will tell.

[Update: No dice].

Binomial Pronunciation: — pack-ee-RISE-us ~ eh-ROSE-us

Archaic synonyms— Cacara erosa; Dolichos erosus, Dolichos bulbosus; Pachyrhizus bulbosus; P. tuberosus; P. angulatus.

Is the Jícama Plant Toxic?

The short answer is YES!

While the root itself is quite edible and nutritious, all other parts of the Pachyrhizus erosus vine, including the root epidermis, leaves, and seeds contain an insecticidal and piscicidal toxin called rotenone.

Rotenone, or 2R,6aS,12aS)-1,2,6,6a,12,12a-hexahydro-2-isopropenyl-8,9-dimethoxychromeno[3,4-b]furo[2,3-h]chromen-6-one

Rotenone disrupts the respiratory mitochondrial chain [7], and if the the vegetative/rotenone containing parts of Pachyrhizus erosus are consumed, death can occur. One Taiwanese man, said to have eaten 2 lbs of uncooked jícama seeds, died only two hours later of respiratory failure [6].

Yes, eating any part of this plant besides the crispy white tuber is bad news, however, rotenone is not a heat-stable toxin [7].

In a pamphlet produced by the U.S. Navy during World War II, called Edible and poisonous Plants of the Caribbean Region, the Navy asserted that the “young pods can be cooked and eaten like string beans” [2]. The consumption of cooked young pods may be warranted in survival situations as cooking and/or drying the plants seeds has been shown to eliminate rotenone content by up to 80% [7].

Jícama Habitat

Pachyrhizus erosus is native to the tropical and subtropical areas of the Americas, but is currently naturalized in Southeast Asia.

How to Prepare Jícama

In the Americas, jícama is often grated into a slaw or cut into sticks and combined with various chili powders, citrus juices, a little vegetable oil, and pinches of salt and sugar to create a cold salad or side [e] [h]. It can be diced and utilized as a crispy addition to pico de gallo, or ceviche.

Jícama can be julienned, seasoned, and baked as “French fries” [f][I], or cooked and combined with sugar and coconut as a sweet desert [g].

In CHINA, jícama is often stir fried with other vegetables like carrots and shallots, soy sauce, garlic, and MSG [a], or scrambled with eggs [b]. Of course, the jícama is also known to make a great cold side salad with citrus and sugar [c], or with sesame, soy sauce, and vinegar [d].

Jicama can be preserved and canned in the form of a coleslaw [j], pickles [k], and relish [l].

Jícama is most often served cold and raw as a cooling and thirst quenching vegetable. I highly recommend this. As you see in the picture below, we tried the time-honored lime juice + Tajin treatment with raw tuber, and on the left we lightly coated the jícama in olive oil and Tajin and air fried them.

Jícama two Ways: Photo by Sophia Healey (2021)

As you see, the jícama lost much of its mass to evaporation when air fried. The end product was a sweaty and limp impersonation of French fries.

Jícama Nutritional Value

Jícama is high in vitamin C, providing up to 40% of your recommended daily intake in a single serving [9]. This root is 80-90% water, is full of dietary fiber, and, hey diabetics, it also has a low glycemic index for worry-free snacking [10].

Ethnobotany of Jícama

In MEXICO, jícama seeds were ground and steeped in oil to be used as a topical medicine to combat psoriasis, scabies, itching, and various skin afflictions [4]. in MEXICAN folk medicine, a tincture of the seeds is used to kill head lice [3].

Indigenous people of French Guiana use Pachyrhizus erosus seeds to poison and eat fish [4].

In INDONESIA, the root of Pachyrhizus erosus is used as a sunscreen, and to whiten the skin [11].

Jícama in Music

The following song by Angelica Garcia was on Barack Obama, and the New York Times’ greatest songs lists. With any luck, you’ll be bopping around to the tune of “jícama, jícama” for the rest of your life whenever you see this plant.

You are welcome!

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For my beautiful wife and son, as always.

References are available in the comments. While you are there… I’d love to hear from you!