Plant Name: Dioscorea alata L.

Common name

Marathi:                Chaivel/ Chaikand/ Chayavel

Hindi:                    Ratalu

English:                Purple yam

Jawhar:                 Chaivel/ Chaikand/ Chayavel

Interesting facts and history

1. alata is a highly invasive plant outside cultivated areas. It is included in the Global Compendium of Weeds, and is listed as a noxious weed in Florida Exotic Pest Plant Council and as an invasive species in Cuba, Costa Rica and several islands in the Pacific.

Identification guide

Stem

Stem twining to right, 4-5-winged; wings sometimes reduced to ribs. Bulbils globose, ovoid or obpyriform, occasionally with rootlets.

Leaves 

Leaves opposite or rarely subopposite, 7-18 x 4-10 cm, broadly ovate or deltoid-ovate, base cordate or subsagittate, apex acuminate, primary veins 7; petiole to 8 cm long, winged. Male Spike on axillary branchlets, paniculate; rachis winged.

Flowers

Flowers 1.5 mm long; bracts to 1 mm long, deltoid-ovate; tepals 1-1.5 mm long, widely ovate, obtuse; stamens 6, free; pistillode conical. Female spike solitary in axils, axis 10-20 cm long. Flowers laxly arranged, sessile; bracts 1-1.5 mm long, ovate; tepals fleshy, c. 1 mm long, broadly ovate; staminodes 6, very small; ovary c. 3 mm long. Capsule 2-2.5 mm long, broadly obcordate.

Tubers

Tubers one to several, polymorphic, variously branched or lobed.

Habit / Habitat

It is a climber. Mostly prefer tropical areas and, yams occur at the edges or in the canopy gaps of rainforests and woodlands.

Occurrence

1) Availability of the plant species in India: Moist deciduous and evergreen forests of India

2) Global distribution: Native of Asia and Africa, however it has been recorded that Chinese yam has increased its range in northern as well as southern US habitats also

Edible parts

World wide use                                         Tubers        

Used by tribal community in Jawhar       Tubers

Method of consumption

Jawhar tribal

Tender leaves mixed with other wild vegetable (especially with Dioscorea sp.) and cooked to remove itchiness after taste.

Other Recipe

Baked Purple Yam and Paneer Cake

Makes 4 servings

Ingredients

To Be Mixed Into A Yam Mixture

3 cups cooked and grated purple yam (kand), 1 tbsp green chilli paste

1 tsp ginger (adrak) paste, 1 tbsp sugar

1 1/2 tbsp lemon juice, 3 tbsp finely chopped coriander (dhania)

3/4 cup roasted and coarsely crushed peanuts, salt to taste

To Be Mixed Into A Stuffing

1 cup grated paneer (cottage cheese), 3 tbsp finely chopped onions

3 tbsp finely chopped capsicum, 1 tbsp finely chopped coriander (dhania)

2 tsp finely chopped green chillies, 2 tsp chaat masala, salt to taste

For The Tempering

1 1/2 tbsp oil, 1/2 tsp mustard seeds ( rai / sarson)

1 tbsp sesame seeds (til), a pinch of asafoetida (hing)

1/2 tsp chilli powder, 3 to 4 curry leaves (kadi patta)

Other Ingredients

Oil for greasing, 1/2 cup green chutney

Method

For the tempering

o Heat the oil in small pan, add the mustard seeds and sesame seeds.

o When the seeds crackle, add the asafoetida, chilli powder and curry leaves and sauté on a medium flame for 30 seconds. Keep aside

How to proceed

o Divide the yam mixture into 3 equal portions and keep aside.

o Take a baking dish and grease it with oil.

o Put 1 yam mixture and spread it evenly using a back of a spoon.

o Put the prepared stuffing over it and press it lightly.

o Put the 2nd portion of the yam mixture over it and spread it evenly.

o Pour the chutney over it and spread it.

o Add the remaining yam mixture over it and finally pour the tempering over it and bake in a pre-heated oven at 200°c (400°f) for 25 minutes.

o Serve hot.

Nutritional and medicinal information

Nutritive Significance:

2. Twenty varieties of Dioscorea alata (water yam) were investigated to ascertain the potential health benefits and alternate usage in comparison with Dioscorea rotundata. Their total dietary fiber (TDF), dry matter and amylose contents were found to be ranging from 4.10 to 11.00%, 19.10 to 33.80% and 27.90 to 32.30% respectively. It also contains certain essential minerals like Zinc (10.10-17.60 mg/kg), calcium (260-535 mg/kg) and Magnesium (390-595 mg/kg). TDF contents of the varieties were higher than that reported for brown rice while two varieties had comparable values to whole wheat flour. Moreover, the low sodium but high potassium and TDF contents indicate the possible preventive role that D. alata could play in managing related chronic diseases. There is a need to exploit its use in food fortifications and formulations.

Pharmaceutical significance

1. Aqueous methanolic (50% MeOH) extracts of the tubers (peel and flesh) of nine cultivars of greater yam (Dioscorea alata) were tested for their antioxidant activities. Two cultivars (Ubing upo, purple; LA 096, white) were reported to have very high antioxidant activity which was comparable to α-tocopherol and butylhydroxyanisole (BHA). High activities were found in the 50% and 75% MeOH fractions; these were dried and further subjected to semi- or preparative HPLC chromatography using Develosil column.

Toxicity:

There are no studies to prove the toxic behaviour of purple yam, however its regular consumption have certain side effects:

o Its regular intake can lead to various health related problems such as diarrhea, headache, vomiting and many more.

o It acts as an estrogenic agent hence it should be avoided by people who have severe allergy towards it.

o It also amplifies the risk of clot formation among people who have intensive protein S deficiency.

Harvesting and preserving         

Leaves can be directly harvested from wild.       

Season of collection

Tubers are collected during summers before the onset of monsoons.

How to grow it?

Propagation is usually by tubers or bulbils planted in rainy season and they are usually dug in the dry season the year after planting . It grows for 8-10 months and then enters into a hibernating mode of 3-4 months. Hard soil with a pH ranging from 5.5 to 6.5, temperature around 30-40 degree Celsius and rainfall around 1500 millimeters is required for its growth.

Method of storage

1) Tubers both for propagules as well as for food

Other uses

• Yam is now being studied for manufacturing fructose sweeteners. In Philippines it is consumed as sweet jam.
• D. alata serves as an essential ingredient in minimizing water preservation and also helps to lighten vomiting and sickness symptoms during pregnancy.
• D. alata contains a chemical compound called as diosgenin, which is used to make steroids such as dehydroepiandrosterone.

Classification    

Kingdom:            Plantae

Division:              Spermatophyta

Sub-division:     Angiospermae

Class:                    Monocotyledonae

Series:                  Epigynae

Family:                 Dioscoreaceae

Genus:                 Dioscorea

Species:               alata

References        

1 http://www.stuartxchange.com/Ubi.html

2 http://manoa.hawaii.edu/botany/plants_of_micronesia/index.php/full-database/364-dioscorea-alata

3 http://www.botanical-online.com/english/yam_dioscorea_alata.htm

4 http://www.eattheweeds.com/yam-a-the-alata/

5 http://www.ars-grin.gov/cgi-bin/duke/ethnobot.pl?ethnobot.taxon=Dioscorea%20alata

6 https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?14175

7 The Yam: A tropical root crop, by Lucien Degras (1993) – Macmillan publication, ISBN-13: 9780333574560

8 http://www.cabi.org/isc/datasheet/19293