Amorphophallus konjac: Can You Resist the Lure of the Devil’s Tongue?

Detail of the male and female flowers (Photo A. Culham)

You are probably familiar with Amorphophallus titanum, the titan arum, which has the largest unbranched inflorescence in the world, but do you know about its smaller, red tongued sibling Amorphophallus konjac?

A bunch of A. konjac in bloom
(Photo courtesy of
James Steakley, 2012)

Family Description

A. konjac is a member of the Araceae family (Arum and Duckweed family) within the order Alismatales. Araceae consists of perennial and mostly terrestrial herbs, with some that are aquatic. Distinct features that help indentify members of this monocotyledonous family include bifacial leaves with parallel or netted venation.  The inflorescence is a usually fleshy spadix consisting of many small flowers with a subtending, sometimes colorful, sheathing bract referred to as a spathe.  Raphides and laticifers are both common.  They also tend to have endospermous seeds.[i]

Subfamily Description

There are eight subfamilies represented in the Araceae: Gymnostachydoideae, Orontioideae, Pothoideae, Monsteroideae, Lasioideae, Calloideae, Lemnoideae, and Aroideae.  The genus Amorphophallus lives within Aroideae, the largest of the subfamilies, with 72 genera found in predominantly tropical to subtropical regions.  Amorphophallus is typically limited to the Asian and African tropics.[ii]  There are approximately 170 species within Amorphophallus, some of which have a pleasant or neutral smell.  However, many produce rancid odors that mimic the sent of dead flesh to attract insects for pollination, A. konjac being one of them![iii]

Morphology

An herbaceous perennial, A. konjac produces a single divided leaf from a subterranean globose tuber.  As new leaf growth occurs the tuber begins to reduce in size, later replaced by a new larger tuber during the growing period.  Leaf size correlates to tuber size, which means some can get up to as big as 125cm in diameter.  This is pretty impressive considering A. konjac only has one leaf!  This large bright green leaf divides into many smaller leaflets, which look like many diverging paths off a central road.  The leaflets are supported by a rachis which extends from the characteristic petiole.[iv]  At about 122 to 152cm tall, the fleshy stem exhibits a greenish-pink mottled pattern.[v]  Upon maturation, a single inflorescence emerges from tubers, producing a deep purplish-maroon spathe surrounding the long purple tongue like spadix.  If the smell of rotten flesh isn’t enough to entice carrion flies to help with pollination, the dark purplish-red inflorescence can look like rotten meat.[vi]

Nomenclature

Etymology

Dr Louise Johnson, adopted mother of this wonderful arum. (Photo A. Culham)

Amorphous means “without a clearly defined shape or form” with origins dating back to the mid 18^th century from the New Latin amorphous and the Greek amorphos meaing ‘shapeless’ or ‘misshapen’.[vii]  Phallus means penis and originates in the early 17^th century via Late Latin from the Greek phallos.[viii]  The first known use of the word Amorphophallus occurred in 1836[ix] and meaning “misshapen penis”, aptly referring to the shape of the A. konjac spadix.[x]

Origins of the word konjac prove a bit more difficult to track down, but seem to be derived from the Japanese word konjaku or konnjaku.  The name may be in reference to the Konjaku Monogatari Shu, “A Collection of Tales of Long Ago”, which is an ancient compilation of tales from Japan, China, and India.[xi]  Although there is no known author, this piece of work is considered to be an integral piece of Japanese literature. Despite the potential connection to this literary collection, the full etymology of the word “konjac” remains unknown.

Common Names

There are a variety of common names for A. konjac including, devil’s tongue, elephant-yam, konnyaku, mo-yu, voodoo lily, and snake palm.  Two of these common names are derived directly from plant features of A. konjac: devil’s tongue for the long deep red spadix and snake palm for the unique spotted petiole.[xii]

Synonyms

A. mairei H.Lév.

A. nanus H.Li & C.L.Long

A. palmiformis Durieu ex Rivière

A. rivierei Durand ex Carrière

A. rivierei var. konjac (K.Koch) Engl.

Brachyspatha konjac (K.Koch) K.Koch

Conophallus konjak Schott

C. konniaku Schott ex Fesca

Hydrosme rivierei (Durand ex Carrière) Engl.

Proteinophallus rivierei (Durand ex Carrière) Hook.f.

Tapeinophallus rivierei (Durand ex Carrière) Baill.[xiii]

Distribution

A. konjac is native to South-Central China and was introduced in North-Central and Southeast China, East Himalaya, Korea, Nansei-shoto, Philippines, Thailand, Tibet, and Vietnam.[xiv] Although not represented on the map below, A. konjac is also heavily cultivated throughout Japan and found its way there in the sixth century from China and Korea.[xv]

A. konjac distribution
(Map courtesy of © Digital Image © Board of Trustees, RBG Kew)

 Culinary Importance

I’m not eating that, says MSc Plant Diversity student Will Simpson. (Photo A. Culham)

Amorphophallus are considered to be an important food source throughout many Asian countries and make up a number of their food staples because of the starchy, edible tubers they produce.  Konjac is an especially popular food ingredient in Japan.  Many Japanese grocery stores contain a multitude of A. konjac (known as konnyaku) based food products, like noodles, jelly, flour, and miso-soup.[xvi]  The tubers can be turned into a brown jelly which is used as a vegetarian substitute for gelatin as well as jelly-based desserts.  Although the taste is considered rather bland, many like to eat A. konjac because of its texture and versatility.  It is also widely used as an emulsifier in foods and drinks.[xvii]

Medicinal Uses

Before it was popularized as a food source, people valued A. konjac as a medicinal aid to relieve intestinal ailments.[xviii]  The tubers in A. konjac contain polysaccharides which are used widely throughout China and Japan for commercial konjac glucomannan (KGM) production.[xix]  Glucomannan is a water-soluble dietary fibre.[xx]  Today, glucomannan works to help manage weight, control blood sugar levels, reduce cholesterole, heal wounds more quickly, and improve digestion.[xxi]  The glucomannan in A. konjac is also used as an ingredient in certain cosmetics to help improve skin conditions because as a natural humectant it helps retain moisture.[xxii]  It is also said to alleviate pain caused by rheumatism, and the crushed seeds can be used to stop toothaches.[xxiii]  A. konjac has also been used as a cancer treatment in Japan, but the benefits have yet to be proven.[xxiv]

Globose tuber of A. konjac used in both food and medicine
(Photo courtesy of mr_subjunctive)

Hazards

Although A. konjac is both a popular food item and recognized as having many health benefits, one must be careful when ingesting it.  Eating more than 1kg a day may cause intestinal blockage.[xxv]  In its jelly form, konjac can become a choking hazard so it is best to drink water during consumption.[xxvi]

Ornamental Uses

Despite the rancid smell of A. konjac, many still purchase and proudly display this plant, waiting with bated breaths for the devil’s tongue to reveal itself!

References

[i] Simpson, Michael G. (2010) Plant Systematics. 2nd Edition. Elsevier Academic Press Publications (North America). ISBN 9780123743800

[ii] Heywood, V.H., Brummitt, R.K., Culham, A. & Seberg, O. (2007) Flowering plant families of the world. Kew Books (Europe) Firefly Books (North America). ISBN 9781554072064

[iii] Kew Science (2018) Amorphophallus titanium. Plants of the World Online. http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:84456-1 (Accessed 13/01/2018)

[iv] Master Gardener Program (2018) Voodoo Lily, Amorphophallus konjac. https://wimastergardener.org/article/voodoo-lily-amorphophallus-konjac/ (Accessed 13/1/2018)

[v] Plant Delights Nursery, Inc. (2018) Amorphophallus konjac. Plant Delights Nursery. https://www.plantdelights.com/collections/amorphophallus-corpse-flower/products/amorphophallus-konjac (Accessed 14/1/2018)

[vi] Royal Botanic Gardens, Kew (2018) Amazing Amorphophallus Kew. https://www.kew.org/blogs/in-the-gardens/amazing-amorphophallus (Accessed 14/1/2018)

[vii] Oxford University Press (2018) Definition of amorphous in English by Oxford Dictionaries. https://en.oxforddictionaries.com/definition/amorphous (Accessed 11/1/2018)

[viii] Oxford University Press

[ix] Merriam-Webster (2018) Definition of AMORPHOPHALLUS. https://www.merriam-webster.com/dictionary/amorphophallus (Accessed 11/1/2018)

[x] Isaak, M. (2015) Curiosities of Biological Nomenclature. http://www.curioustaxonomy.net/etym/ribaldry.html (Accessed 12/1/18)

[xi] Kelsey, W. Michael (1975) Konjaku Monogatari-shu. Toward an Understanding of Its Literary Qualities. Monumenta Nipponica, 30 (2): 121. https://www.jstor.org/stable/2383839

[xii] The Exotic Rainforest (2018) Amorphophallus konjac K. Koch. http://www.exoticrainforest.com/Amorphophallus%20konjac%20pc.html (Accessed 14/1/2018)

[xiii] E-monocot (2018) Amorphophallus konjac K.Koch. http://e-monocot.org/taxon/urn:kew.org:wcs:taxon:8190 (Accessed 14/1/2018)

[xiv] Kew Science (2018) Amorphophallus konjac. Plants of the World Online. http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:84377-1 (Accessed 13/01/2018)

[xv] Japan National Tourism Organization (2014). Konnyaku (Konjac), Authentic Japanese product. http://japan-brand.jnto.go.jp/foods/other_food/39/ (Accessed 14/1/2018)

[xvi] NuPasta.inc. (2017) The History and Evolution of Konjac Foods. https://www.nupasta.com/the-history-and-evolution-of-konjac-foods/ (Accessed 14/1/2018)

[xvii] Japan National Tourism Organization

[xviii] Japan National Tourism Organization

[xix] Borompichaichartkul, C. (2016) Tracing the Evolution and Economic Potential of Konjac Glucomannan in Amorphophallus species (Araceae) using Molecular Phylogeny and RAPD Markers. Phytotaxa, 282 (2): 81.

[xx] NuPasta.inc. (2017) What is Konjac?  https://www.nupasta.com/what-is-konjac/ (Accessed 14/1/2018)

[xxi] Burgess, L. (2017) Konjac: 6 potential health benefits. Medical News Today. https://www.medicalnewstoday.com/articles/319979.php (Accessed 14/1/2018)

[xxii] Barresi, T. (2016) Konjac Powder – Ingredient Highlight. Essential Wholesale Resource Library. http://library.essentialwholesale.com/konjac-powder/ (Accessed 14/1/2018)

[xxiii] WebMD LLC (2018) GLUCOMANNAN: Uses, Side Effects, Interactions and Warnings – WebMD. https://www.webmd.com/vitamins-supplements/ingredientmono-205-glucomannan.aspx?activeingredientid=205&activeingredientname=glucomannan (Accessed 14/1/2018)

[xxiv] My Jungle Garden (2018) Amorphophallus konjac. https://myjunglegarden.com/2015/11/amorphophallus-konjac/#.WlusxyOLRsM (Accessed 14/1/2018)

[xxv] Japan National Tourism Organization

[xxvi] Amerman, D. (2017) Side Effects of Konjac Root. https://www.livestrong.com/article/149231-side-effects-of-konjac-root/ (Accessed 14/1/2018)

Images

All photos by Lauryn Gilroy unless otherwise attributed.