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Datasheet

Dioscorea alata (white yam)

Summary

  • Last modified
  • 22 June 2017
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Dioscorea alata
  • Preferred Common Name
  • white yam
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • D. alata is a vigorous twining herbaceous vine, which is an important edible tuber crop but also an invasive plant outside cultivated areas. It is included in the Global Compendium of Weeds (...

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Pictures

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PictureTitleCaptionCopyright
Dioscorea alata (winged yam, uhi); habit at Maui Nui Botanical Garden, Maui.  November 06, 2006
TitleInvasive habit
CaptionDioscorea alata (winged yam, uhi); habit at Maui Nui Botanical Garden, Maui. November 06, 2006
Copyright©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); habit at Maui Nui Botanical Garden, Maui.  November 06, 2006
Invasive habitDioscorea alata (winged yam, uhi); habit at Maui Nui Botanical Garden, Maui. November 06, 2006©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); habit. Maui Nui Botanical Garden, Maui.  November 06, 2006
TitleHabit
CaptionDioscorea alata (winged yam, uhi); habit. Maui Nui Botanical Garden, Maui. November 06, 2006
Copyright©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); habit. Maui Nui Botanical Garden, Maui.  November 06, 2006
HabitDioscorea alata (winged yam, uhi); habit. Maui Nui Botanical Garden, Maui. November 06, 2006©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); habit.  Maui Nui Botanical Garden, Maui.  November 06, 2006
TitleHabit and foliage
CaptionDioscorea alata (winged yam, uhi); habit. Maui Nui Botanical Garden, Maui. November 06, 2006
Copyright©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); habit.  Maui Nui Botanical Garden, Maui.  November 06, 2006
Habit and foliageDioscorea alata (winged yam, uhi); habit. Maui Nui Botanical Garden, Maui. November 06, 2006©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); leaves. Maui Nui Botanical Garden, Maui.  November 06, 2006
TitleLeaves
CaptionDioscorea alata (winged yam, uhi); leaves. Maui Nui Botanical Garden, Maui. November 06, 2006
Copyright©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); leaves. Maui Nui Botanical Garden, Maui.  November 06, 2006
LeavesDioscorea alata (winged yam, uhi); leaves. Maui Nui Botanical Garden, Maui. November 06, 2006©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); flowers. Maui Nui Botanical Garden, Maui.  November 06, 2006
TitleFlowers
CaptionDioscorea alata (winged yam, uhi); flowers. Maui Nui Botanical Garden, Maui. November 06, 2006
Copyright©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); flowers. Maui Nui Botanical Garden, Maui.  November 06, 2006
FlowersDioscorea alata (winged yam, uhi); flowers. Maui Nui Botanical Garden, Maui. November 06, 2006©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); yamlet.  Maui Nui Botanical Garden, Maui.  November 06, 2006
TitleYamlet
CaptionDioscorea alata (winged yam, uhi); yamlet. Maui Nui Botanical Garden, Maui. November 06, 2006
Copyright©Forest & Kim Starr Images-2006. CC-BY-3.0
Dioscorea alata (winged yam, uhi); yamlet.  Maui Nui Botanical Garden, Maui.  November 06, 2006
YamletDioscorea alata (winged yam, uhi); yamlet. Maui Nui Botanical Garden, Maui. November 06, 2006©Forest & Kim Starr Images-2006. CC-BY-3.0

Identity

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Preferred Scientific Name

  • Dioscorea alata L. (1753)

Preferred Common Name

  • white yam

Other Scientific Names

  • Dioscorea aculeata Wight
  • Dioscorea alata var. globosa (Roxb.) Prain
  • Dioscorea alata var. purpurea (Roxb.) A. Pouchet
  • Dioscorea alata var. tarri Prain & Burkill
  • Dioscorea alata var. vera Prain & Burkill
  • Dioscorea atropurpurea Roxb.
  • Dioscorea colocasiifolia Pax
  • Dioscorea eburina Lour.
  • Dioscorea eburnea Lour.
  • Dioscorea globosa Roxb. (1832)
  • Dioscorea javanica Queva
  • Dioscorea purpurea Roxb. (1832)
  • Dioscorea rubella Roxb.
  • Dioscorea sapinii De Wild.
  • Dioscorea sativa Munro
  • Dioscorea vulgaris Miquel (1859)
  • Elephantodon eburnea (Lour.) Salisb.
  • Polynome alata (L.) Salisb.

International Common Names

  • English: Asiatic yam; greater yam; ten-months yam; water yam; winged yam; yam (asiatic); yam (white)
  • Spanish: cara; name; name amarillo; name blanco; name bombo; name cola de pato; name de agua; name morado; name negro; name pelado; tabena
  • Portuguese: cará-inhame; cará-roxo
  • French: igname; igname ailée; igname de Chine; pacala
  • Chinese: shen shu

Local Common Names

  • Brazil: cara-inhama
  • Cambodia: dâmlông chiem moan; dâmlông phluk
  • Cuba: name de Guinea
  • Dominican Republic: name de monte pujador; yame blanco; yame de gallina
  • Germany: Wasser- Yam
  • Haiti: igname bombarde; igname caracol; igname française
  • India: purple yam; ratalu; violet yam
  • Indonesia: huwi; lame; uwi
  • Laos: man hlièmx
  • Malaysia: pokok ubi; ubi kipas; ubi tiyang
  • Netherlands: yamswortel, witte
  • Papua New Guinea: kolpur; nyaing; yam tru
  • Philippines: kinampay; ube; ubi
  • Puerto Rico: name de mina
  • Thailand: man-liam; man-sao; man-thu
  • United States Virgin Islands: native yam
  • Vietnam: cur casi; cur mowx; khoai vaje

EPPO code

  • DIUAL (Dioscorea alata)

Summary of Invasiveness

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D. alata is a vigorous twining herbaceous vine, which is an important edible tuber crop but also an invasive plant outside cultivated areas. It is included in the Global Compendium of Weeds (Randall, 2012), and is listed as a “noxious weed” in Florida (Florida Exotic Pest Plant Council, 2011; USDA-NRCS, 2012) and as an invasive species in Cuba, Costa Rica and several islands in the Pacific (Chacón and Saborio, 2012; Gonzalez-Torres et al., 2012; PIER, 2012). In Florida, this species is classified as an invasive plant category I with the potential to modify and collapse native plant communities by displacing native species, changing community structures and altering ecological functions (Florida Exotic Pest Plant Council, 2011).

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Dioscoreales
  •                         Family: Dioscoreaceae
  •                             Genus: Dioscorea
  •                                 Species: Dioscorea alata

Notes on Taxonomy and Nomenclature

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The family Dioscoreaceae includes about 4–6 genera and 870 species. The members of this family are often herbaceous climbing vines. The circumscription of this family still remains controversial. While some authors define this family in a strict context including only the genera Dioscorea, Tamus and Rajania; other authors define this family in a broader context including also the genera Avetra, Trichopus, Stenomeris and Tacca (Raz, 2003). The genus Dioscorea includes about 350–800 species distributed largely in the tropics, but also in warm and temperate regions. Species in this genus are dioecious, twining, and herbaceous to woody vines with single or clustered large tubers some of which are edible and are known as “yams” (Acevedo-Rodríguez, 2005). D. alata is widely cultivated throughout the tropics for its edible tubers and bulbils.

Description

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Non-woody vine, twining (toward the right), glabrous, attaining 10-15 m in length. Root system fibrous, shallow, mostly confined to the top 1 m of the soil. Tubers usually single, varying in size and shape, often very large; cylindrical or clavate in shape (often found as deep as 1.5 m) or globose, stout and short, pyriform, often variously lobed or fingered and fasciated or curved; skin brown to black; flesh white, cream or purplish (superficially or throughout). Stems are quadrangular, with 4 longitudinal winged, undulate, green or reddish projections; mature stems (at the base) cylindrical and spiny. Leaves are mostly opposite, sometimes alternate on branches of rapid growth, coriaceous, broadly ovate, 5-7-veined, 10-30 × 5-18 cm, the apex acute or acuminate, sometimes reflexed, the base cordiform; upper surface dark green, shiny, with the venation sunken; lower surface pale green, dull, with prominent venation; petioles 4-12 cm long, 4-winged, forming an auriculate sheath at the base, with a pair of pseudostipules that clasp the stem; bulbils elongate, pendulous, attaining 15 cm long, produced when the leaves begin to wither. Inflorescences are axillary, unisexual, pendulous. Staminate inflorescences are paniculate, 5-15 cm long, with numerous lateral and flexuous spikes that contain numerous male flowers. Pistillate inflorescences are racemose, with few flowers. Perianth 1-1.5 mm long in staminate flowers; 2-2.8 mm long in pistillate flowers. Fruit a 3-locular capsule, 2-3 cm wide, each locule flattened like a wing, with two seeds inside (Acevedo-Rodríguez, 2005). Seed orbicular, winged all round.

Plant Type

Top of page Herbaceous
Perennial
Seed propagated
Vegetatively propagated
Vine / climber

Distribution

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D. alata is native to southeastern Asia (Acevedo-Rodríguez, 2005) and entered into cultivation there. This species is virtually unknown in the wild state, except for occasional reports. It has the largest global distribution of all the yams, and is grown throughout the tropics. D. alata is widely grown in the West Indies (where it is the most important yam grown), in West Africa (where it is second only to Dioscorea rotundata), and in Central America. In South-East Asia, it is the most important species and is grown in virtually all countries of the region, especially in Indonesia, Malaysia, Papua New Guinea, Philippines, and Vietnam. It has become naturalized in Florida and parts of the West Indies after escaping from cultivation.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

Brunei DarussalamPresentGovaerts, 2013
China
-GuangdongPresentFlora of China Editorial Committee, 2012Cultivated
-HubeiPresentFlora of China Editorial Committee, 2012Cultivated
India
-Arunachal PradeshPresentGovaerts, 2013
-AssamPresentGovaerts, 2013
Indonesia
-JavaPresentGovaerts, 2013
-Nusa TenggaraPresentGovaerts, 2013
-SulawesiPresentGovaerts, 2013
-SumatraPresentGovaerts, 2013
JapanPresentFAO, 2013; Govaerts, 2013
Malaysia
-Peninsular MalaysiaPresentGovaerts, 2013
MyanmarPresentGovaerts, 2013
NepalPresentGovaerts, 2013
PhilippinesPresentFAO, 2013; Govaerts, 2013
SingaporePresentGovaerts, 2013
TaiwanPresentGovaerts, 2013
ThailandPresentGovaerts, 2013
VietnamPresentGovaerts, 2013

Africa

AngolaPresentGovaerts, 2013
BeninPresentFAO, 2013; Govaerts, 2013
BurundiPresentFAO, 2013; Govaerts, 2013
CameroonPresentFAO, 2013; Govaerts, 2013
Central African RepublicPresentFAO, 2013; Govaerts, 2013
ComorosPresentFAO, 2013; Govaerts, 2013
Congo Democratic RepublicPresentGovaerts, 2013
EritreaPresentGovaerts, 2013
GabonPresentFAO, 2013; Govaerts, 2013
GuineaPresentFAO, 2013; Govaerts, 2013
Guinea-BissauPresentGovaerts, 2013
MadagascarPresentGovaerts, 2013
MalawiPresentGovaerts, 2013
MaliPresentFAO, 2013; Govaerts, 2013
MozambiquePresentGovaerts, 2013
RwandaPresentFAO, 2013; Govaerts, 2013
SeychellesPresentGovaerts, 2013
TanzaniaPresentGovaerts, 2013
TogoPresentFAO, 2013; Govaerts, 2013
ZambiaPresentGovaerts, 2013

North America

MexicoPresentVillaseñor and Espinosa-Garcia, 2004
USA
-FloridaPresent Invasive Wunderlin and Hansen, 2008Invasive Category I and noxious weed
-GeorgiaPresentCarter et al., 2009
-LouisianaPresentThomas and Allen, 1997

Central America and Caribbean

Antigua and BarbudaWidespreadBroome et al., 2007; FAO, 2013
BahamasPresentCorrell and Correll, 1982
BelizePresentBalick et al., 2000; FAO, 2013
Costa RicaPresent Invasive Chacón and Saborío, 2012; FAO, 2013
CubaPresent Invasive González-Torres et al., 2012; FAO, 2013
DominicaWidespreadBroome et al., 2007; FAO, 2013
Dominican RepublicPresentAcevedo-Rodríguez and Strong, 2012; FAO, 2013
El SalvadorPresentGovaerts, 2013
GrenadaWidespreadBroome et al., 2007; FAO, 2013
GuatemalaPresentGovaerts, 2013
HaitiPresentAcevedo-Rodríguez and Strong, 2012; FAO, 2013
HondurasPresentDavidse et al., 1994
JamaicaPresentAdams, 1972; FAO, 2013
MartiniqueWidespreadBroome et al., 2007; FAO, 2013
MontserratWidespreadBroome et al., 2007
Netherlands AntillesWidespreadBroome et al., 2007Saba, St. Bartholomew, St. Eustatius
NicaraguaPresentGovaerts, 2013
PanamaPresentCorrea et al., 2004; FAO, 2013
Puerto RicoPresentAcevedo-Rodríguez and Strong, 2012; FAO, 2013
Saint Kitts and NevisWidespreadBroome et al., 2007; FAO, 2013
Saint LuciaWidespreadGraveson, 2012; FAO, 2013
Trinidad and TobagoPresentFAO, 2013; Govaerts, 2013
United States Virgin IslandsPresentAcevedo-Rodríguez and Strong, 2012St. John

South America

Brazil
-Mato GrossoPresentForzza et al., 2012Cultivated
-Minas GeraisPresentForzza et al., 2012Cultivated
-ParanaPresentForzza et al., 2012Cultivated
-Rio de JaneiroPresentForzza et al., 2012Cultivated
-Sao PauloPresentForzza et al., 2012Cultivated
ColombiaPresentIdárraga-Piedrahita et al., 2011; FAO, 2013
French GuianaPresentFunk et al., 2007
GuyanaPresentFunk et al., 2007; FAO, 2013
PeruPresentGovaerts, 2013
SurinamePresentFunk et al., 2007
VenezuelaPresentHokche et al., 2008Also in Venezuelan Antilles

Oceania

Australia
-Australian Northern TerritoryPresentGovaerts, 2013
-QueenslandPresentGovaerts, 2013
FijiPresentFAO, 2013; Govaerts, 2013
Marshall IslandsPresentGovaerts, 2013
Micronesia, Federated states ofPresentGovaerts, 2013
NiuePresentFAO, 2013; Govaerts, 2013
Papua New GuineaPresentFAO, 2013; Govaerts, 2013
Pitcairn IslandPresentGovaerts, 2013
SamoaPresentFAO, 2013; Govaerts, 2013
TongaPresentFAO, 2013; Govaerts, 2013
Wallis and Futuna IslandsPresentFAO, 2013; Govaerts, 2013

History of Introduction and Spread

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D. alata was apparently introduced to the Americas by Portuguese and Spanish slave traders in the 1500s (Coursey, 1967). In the West Indies, D. alata was reported for the island of Cuba as a “cultivated plant” as early as 1854 (Pichardo, 1854). In 1864, it is reported as commonly cultivated in Jamaica, Haiti, and the French Caribbean islands (Grisebach, 1864). In Puerto Rico, D. alata was first reported by Domingo Bello in 1883 (Bello, 1883). In the early twentieth century, Ignaz Urban reported this species as “naturalized” in Puerto Rico, Hispaniola, Guadeloupe, St. Vincent, Martinique, and Trinidad (Urban, 1905). Similarly, in 1924, N.L. Britton reported this species as “spontaneous after cultivation” for the islands of Puerto Rico, St Thomas, St. John, St. Croix, Tortola, Bahamas, Hispaniola, and Saba (Britton, 1924).

Risk of Introduction

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D. alata is an aggressive invasive plant that is widely cultivated in tropical regions of the world. Plants of D. alata have escaped from cultivation and spread rapidly into natural forest, climbing into the canopy of mature trees and forming dense stands (Langeland et al., 2008). It is a fast-growing plant that can be dispersed by seed, underground tubers, and bulbils which sprout forming new plants (Langeland et al., 2008). Thus, the probability of invasion of this species, especially in habitats near to cultivated areas, remains high.

Habitat

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D. alata can be found growing in partially to dense shaded areas in moist forests, mesic forests, and hardwood forests (Langeland et al., 2008). In Puerto Rico, this species is very common is disturbed areas and moist secondary forests at lower and middle elevations (Acevedo-Rodríguez, 2005). In Florida, D. alata has been documented in sandhills, maritime hammocks, upland pine forests, hardwood hammocks, mesic flatwoods, and ruderal communities (Langeland et al., 2008).

Habitat List

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CategoryHabitatPresenceStatus
Terrestrial-managed
Cultivated / agricultural land Present, no further details Harmful (pest or invasive)
Cultivated / agricultural land Present, no further details Natural
Cultivated / agricultural land Present, no further details Productive/non-natural
Disturbed areas Present, no further details Harmful (pest or invasive)
Disturbed areas Present, no further details Natural
Managed grasslands (grazing systems) Present, no further details Harmful (pest or invasive)
Managed grasslands (grazing systems) Present, no further details Natural
Managed grasslands (grazing systems) Present, no further details Productive/non-natural
Rail / roadsides Present, no further details Harmful (pest or invasive)
Rail / roadsides Present, no further details Natural
Terrestrial-natural/semi-natural
Natural forests Present, no further details Harmful (pest or invasive)
Natural forests Present, no further details Natural
Riverbanks Present, no further details Harmful (pest or invasive)
Riverbanks Present, no further details Natural

Biology and Ecology

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Genetics

D. alata is a polyploid species with several ploidy levels and its basic chromosome number varies from 2n = 40 to 2n = 80 (Arnau et al., 2009).

Reproductive Biology

D. alata is a dioecious species, with staminate and pistillate flowers occurring on separate plants. Staminate flowers may remain open for 4–5 hours while pistillate flowers open for 9–11 days. A study of the floral biology of this species has demonstrated that natural pollination is practically absent but parthenocarpic fruit development has been observed (Abraham and Nair, 1990).

In Puerto Rico, this species has been collected in flower in October and November and in fruit in January (Acevedo-Rodríguez, 2005).

Physiology and Phenology

As with most other edible yams, the growth and development of D. alata falls roughly into four phases. The first phase spans from 0-6 weeks after emergence, and is characterized by extensive root and vine growth, but very limited leaf expansion. The second phase, lasting from 6-12 weeks after emergence, is characterized by limited root growth, extensive shoot and leaf growth, and the onset of tuber formation. The third phase, lasting until the end of the season, is characterized by tuber bulking and maturity. Root and shoot growth are very limited in this phase. The total growing period is 8-10 months. In the fourth phase, the shoot senesces and dies back, and the tubers enter a dormant period lasting 2-4 months before sprouting again. 

Environmental Requirements

D. alata grows in areas with mild temperatures (around 15-35°C) and high precipitation (>1000 mm annual rainfall), at low to middle elevations. When cultivated, an annual rainfall of 1000-1500 mm, distributed over at least 6-7 months, is required. It is adapted to partially to fully shaded conditions, but does not tolerate frost. Tuberization is promoted by short days (less than 12 h). As with many species within the genus Dioscorea this species climbs by twining on other plants in order to capture sunlight (Langeland and Burks, 2008). D. alata is sensitive to aluminium toxicity in the soil, but tolerates poorer soils than most other cultivated yam species.

Cultivated Forms

D. alata is the most important yam for South-East Asia and is easily recognized by its quadrangular winged stems. The variability of the tubers in form, size, weight, colour and flesh is so great that in every country where it grows and is used, many forms, selections and cultivars exist, all with their own vernacular names.

Because D. alata is not known as a wild plant in its original range, a classification into cultivar groups and cultivars is most suitable, but there is no satisfactory world-wide system. In a study of 235 different cultivars from all over the world (Martin and Rhodes, 1977), 15 cultivar groups could be distinguished. The greatest variability was present in materials from New Guinea, Indonesia and the Philippines. Relevant groups for South-East Asia include:

- cv. group Purple Compact. Plants with a large content of anthocyanin, especially in the petiole; well developed, ruffled wings; tubers short with coloured flesh and cortex. Principal region: the Philippines. Cultivars include 'Morado', 'Vino Violeta', 'Kinampay'.

- cv. group Primitive Purple. Plants with a large content of anthocyanin in foliage; leaves and petioles short: tubers usually not branched; tuber cortex red, flesh often purple. Principal region: New Guinea. Some cultivars: 'Buster', 'Kiubu', 'Aupik'.

- cv. group Primitive Green. Plants with light green leaves, foliage almost free of anthocyanin; tubers long with prominent neck; cortex and flesh very white, cooking qualities poor. Principal regions: New Guinea, Indonesia. Cultivars include 'Masi', 'Lanswa', 'Suabab'.

-cv. group Compact. Plants with foliage tinged with anthocyanin; tubers short, wide; little coloration of cortex and flesh, very good cooking qualities. Principal regions: New Guinea and the Philippines. Some cultivars: 'Uhbisi', 'Toma', 'Kabusak'.

-cv. group Poor White. Plants with solitary tubers; cortex coloured but flesh whitish, pronounced gradient of colour and texture. Principal regions: New Guinea, India. Cultivars include 'Baron', 'Toa', 'Goarmago'.

Climate

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ClimateStatusDescriptionRemark
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Preferred < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Tolerated Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -2
Mean maximum temperature of hottest month (ºC) 35
Mean minimum temperature of coldest month (ºC) 0

Rainfall

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ParameterLower limitUpper limitDescription
Mean annual rainfall7004000mm; lower/upper limits

Rainfall Regime

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Soil Tolerances

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Soil drainage

  • free
  • seasonally waterlogged

Soil reaction

  • acid
  • neutral

Soil texture

  • light
  • medium

Special soil tolerances

  • shallow

Notes on Natural Enemies

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Glomerella cingulata is a serious disease affecting D. alata which results in blackening and dieback of the leaves. The yam beetle (Heteroligus spp.), scale insects and mealybugs may infest the tubers. Nematodes also attack plant of D. alata, resulting in warty appearance of the tubers.

Means of Movement and Dispersal

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D. alata spreads by seeds which can be dispersed by wind and by water and vegetatively by underground tubers and bulbils (Acevedo-Rodríguez, 2005; Langeland et al., 2008).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Crop productionEdible underground tubers (yams) and bulbils Yes Yes
Escape from confinement or garden escapeBulbils, plant fragments Yes Yes Langeland et al., 2008
ForageTubers (yams) and bulbils are also used to feed animals Yes Yes
People foraging Yes Yes

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Consumables Yes Yes
Debris and waste associated with human activitiesTubers (yams) and bulbils Yes Yes Langeland et al., 2008
Machinery and equipmentTubers (yams) and bulbils Yes Yes Langeland et al., 2008
Soil, sand and gravelTubers (yams) and bulbils Yes Yes Langeland et al., 2008
WindWinged seeds Yes Langeland et al., 2008

Impact Summary

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CategoryImpact
Economic/livelihood Positive and negative
Environment (generally) Negative

Environmental Impact

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D. alata is considered an aggressive and fast-growing vine with the potential to form dense colonies that engulf native vegetation. It climbs high into mature tree canopies and shades trees and shrubs in the understory (Langeland et al., 2008). This species also has the capability to completely out-compete native vegetation communities by displacing native species, changing community structures and altering ecological functions (Florida Exotic Pest Plant Council, 2011).

Risk and Impact Factors

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Impact mechanisms

  • Competition - monopolizing resources
  • Pest and disease transmission
  • Poisoning
  • Rapid growth
  • Rooting

Impact outcomes

  • Modification of successional patterns
  • Monoculture formation
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species

Invasiveness

  • Benefits from human association (i.e. it is a human commensal)
  • Fast growing
  • Has a broad native range
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
  • Highly mobile locally
  • Long lived
  • Pioneering in disturbed areas
  • Proved invasive outside its native range
  • Reproduces asexually
  • Tolerant of shade
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc

Likelihood of entry/control

  • Highly likely to be transported internationally deliberately
  • Highly likely to be transported internationally illegally

Uses

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The tubers and larger bulbils of D. alata are consumed by humans as a starchy staple, after cooking in various ways. They can be processed into yam flakes or yam flour. There are also used as source of starch. The cultivars with purple flesh are used in the manufacture of ice-cream and cakes. D. alata is also used in traditional medicine in Southeastern Asia. Tubers and bulbils are also used as an animal feed resource (USDA-ARS, 2012).

Uses List

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Animal feed, fodder, forage

  • Fodder/animal feed

Environmental

  • Agroforestry

General

  • Ornamental

Human food and beverage

  • Flour/starch
  • Root crop
  • Vegetable

Medicinal, pharmaceutical

  • Traditional/folklore

Similarities to Other Species/Conditions

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D. alata may be confused with Dioscorea bulbifera. However, D. bulbifera has small or lacks underground tubers and has more numerous bulbils (Langeland and Burks, 2008). Additionally, D. bulbifera has alternate leaves while D. alata has leaves which are mostly opposite with a pair of pseudostipules that enclose the stem (Acevedo-Rodríguez, 2005). Stems in D. alata are longitudinally winged while in D. bulbifera they are cylindrical (Acevedo-Rodríguez, 2005).

Prevention and Control

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Mechanical Control

All bulbils and tubers should be removed to prevent spread into new areas. Dense stands should be removed using specialized machinery. 

Chemical Control

Chemical control should include mechanical cutting followed by applications of glyphosate or triclopyr to the cut stems. Follow-up treatments are recommended at 6-month intervals until control is completed.

Bibliography

Top of page Alozie SO, Nwankiti AO, Oti E, 1987. Source of resistance in anthracnose blotch disease of water yam (Dioscorea alata) caused by Colletotrichum gloeosporioides Penz. 2. Relationship between phenol content and resistance. Beitrage zur Tropischen Landwirtschaft und Veterinarmedizin, 25(1):55-59.

King G, Hackett C, 1986. Tabular description of crops grown in the tropics. 13. Greater yam (Dioscorea alata L.). Technical Memorandum 86(4). Canberra, Australia: Commonwealth Scientific and Industrial Research Organization (CSIRO).

Martin FW, 1976. Dioscorea alata. In: Martin FW, Sadik S, Degras L, eds. Tropical yams and their potential. Part 3. Agriculture Handbook No 495. Washington, DC, USA: United States Department of Agriculture (USDA).

Martin FW, Rhodes AM, 1977. Intra-specific classification of Dioscorea alata. Tropical Agriculture (Trinidad), 54:1-13.

Onwueme IC, 1978. The tropical tuber crops. Chichester, UK: Wiley, 3-106.

Udoessien ET, Ifon ET, 1992. Chemical evaluation of some antinutritional constituents in four species of yam. Tropical Science (UK), 32(2):115-119.

References

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Abraham K; Nair PG, 1990. Floral biology and artificial pollination in Dioscorea alata L. Euphytica, 48(1):45-51.

Acevedo-Rodríguez P, 2005. Vines and climbing plants of Puerto Rico and the Virgin Islands. Contributions from the United States National Herbarium, 51:483 pp.

Acevedo-Rodríguez P; Strong MT, 2012. Catalogue of the Seed Plants of the West Indies. Smithsonian Contributions to Botany, 98:1192 pp. Washington DC, USA: Smithsonian Institution. http://botany.si.edu/Antilles/WestIndies/catalog.htm

Adams CD, 1972. Flowering plants of Jamaica. Mona, Jamaica: University of the West Indies.

Arnau G; Nemorin A; Maledon E; Abraham K, 2009. Revision of ploidy status of Dioscorea alata L. (Dioscoreaceae) by cytogenetic and microsatellite segregation analysis. TAG Theoretical and Applied Genetics, 118(7):1239-1249. http://www.springerlink.com/content/24870711l1j2135j/?p=b35a57c4a3c843f297228254f5ed2a45&pi=1

Balick MJ; Nee M; Atha DE, 2000. Checklist of the vascular plants of Belize. Memoirs of the New York Botanical Garden, 85:1-246.

Bello D, 1883. [English title not available]. (Apuntes para la flora de Puerto Rico. Segunda parte. Monoclamídeas.) Anales de la Sociedad Española de Historia Natural, 12:103-130.

Britton NL, 1924. Botany of Porto Rico and Virgin Islands. Scientific Survey of Porto Rico and Virgin Islands. New York, USA: New York Academy of Sciences, 200 pp.

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Correll DS; Correll HB, 1982. Flora of the Bahama Archipelago. Vaduz, Germany: J. Cramer, 1692 pp.

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FAO, 2013. FAOSTAT database. Rome, Italy: FAO. http://faostat3.fao.org/home/index.html [2011 data taken in 2013.]

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Florida Exotic Pest Plant Council, 2011. Florida EPPC's 2011 Invasive Plant Species List. http://www.fleppc.org/list/11list.html

Forzza RC; Leitman PM; Costa AF; Carvalho Jr AA, et al. , 2012. List of species of the Flora of Brazil (Lista de espécies Flora do Brasil). Rio de Janeiro, Brazil: Rio de Janeiro Botanic Garden. http://floradobrasil.jbrj.gov.br/2012/

Funk V; Hollowell T; Berry P; Kelloff C; Alexander SN, 2007. Checklist of the plants of the Guiana Shield (Venezuela: Amazonas, Bolivar, Delta Amacuro; Guyana, Surinam, French Guiana). Contributions from the United States National Herbarium, 584 pp.

González-Torres LR; Rankin R; Palmarola A (eds), 2012. Invasive plants in Cuba. (Plantas Invasoras en Cuba.) Bissea: Boletin sobre Conservacion de Plantad del Jardin Botanico Nacional, 6:1-140.

Govaerts R, 2013. World Checklist of Dioscoraceae. London, UK: Royal Botanic Gardens, Kew. http://apps.kew.org/wcsp/

Graveson R, 2012. Plants of Saint Lucia. http://www.saintlucianplants.com

Grisebach AHR, 1864. Flora of the British West Indian Islands. London, UK: Lovell Reeve & Co., 806 pp.

Hokche O; Berry PE; Huber O, 2008. Nuevo Catálogo de la Flora Vascular de Venezuela (New catalogue of the vascular flora of Venezuela). Caracas, Venezuela: Fundación Instituto Botánico de Venezuela, 860 pp.

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Langeland KA; Cherry HM; McCormick CM; Craddock Burks KA, 2008. Identification and Biology of Non-native Plants in Florida's Natural Areas. Gainesville, Florida, USA: University of Florida IFAS Extension.

Langeland KA; Craddock Burks KA, 2008. Datasheet: Dioscorea alata L. online information., USA: Florida Exotic Pest Plant Council. http://www.fleppc.org/ID_book/Dioscorea%20alata.pdf

Martin FW; Rhodes AM, 1977. Intra-specific classification of Dioscorea alata. Tropical Agriculture, Trinidad and Tobago, 54(1):1-13.

Pichardo E, 1854. Geografía de la Isla de Cuba ([English title not available]). Havana, Cuba: Establecimiento Tipográfico de D.M. Soler, 200 pp.

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Raz L, 2003. Dioscoreaceae: R. Brown: Yam Family. In: Flora of North America [ed. by Flora of North America Editorial Committee]. New York, USA: Oxford University Press, 479-485.

Thomas RD; Allen CM, 1997. Atlas of the Vascular Flora of Louisiana, Volumes 1-3. Baton Rouge, USA: Louisiana Department of Wildlife and Fisheries.

Urban I, 1905. Symbolae Antillanae. Volumen IV. Berlin, Germany: Fratres Borntraeger, 771 pp.

USDA-ARS, 2012. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

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Wunderlin RP; Hansen BF, 2008. Atlas of Florida Vascular Plants. Florida, USA: University of South Florida. http://www.plantatlas.usf.edu/

Contributors

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02/04/13 Updated by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA

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