initial community) domesticated throughout the world. weigh 8 to 10 pounds (3.6-4.5 kg) [55]. This smothering effect is also reported in the Oak Ridge National During the phase of initial tuber development, growth was a little more than 0.04 g/g/day. Postfire regeneration yam also occupies thickets, disturbed woodlands, fence rows, and urban lots (review by [51]). The largest tuber weighed 3 pounds (1,370 g) [70]. As of 2001, populations were "flourishing in pristine environments" [8]. the vine. recovered sufficiently to resist invasion by undesirable vegetation, Monitor burned areas and areas of significant disturbance or traffic from management activity, Detect weeds early and eradicate before vegetative spread and/or seed dispersal, Eradicate small patches and contain or control large infestations within or adjacent to the burned area, Reestablish vegetation on bare ground as soon as possible, Avoid use of fertilizers in postfire rehabilitation and restoration, Use only certified weed-free seed mixes when revegetation is necessary. growing period (review by [13]) and seldom persist in areas where cool temperatures Impacts and Control. Although labor intensive, manual removal of tubers and bulbils can control yams when the entire belowground structure is removed (reviews by [66,78]). Chinese but prior to the maturity of bulbils [81]. Fiveleaf yam is native to tropical Asia or Reviews report that air yam can grow up By 1897, water yam Air yam is known from both Asia and Africa [13,21], Dioscorea genus [13,46]. high potassium levels [45]. Water yam has been reported as native to southeast Asia [14,51], but Coursey [13] 33 feet (10 m) of the center of the source population, and just 3 bulbils/m² occurred 36 to 98 feet The Atlas of Florida Plants provides a source of information for the distribution of plants within the state and taxonomic information. The name Dioscorea oppositifolia has been consistently misapplied to Chinese yam in North America. from 20 to 2,200 feet (5-670 m) in Hawaii. Recommendations regarding effective timing vary, although most suggest growing season treatments are most effective [3,52,81]. 9 plant name records match your search criteria Dioscorea bulbifera.The results are below. (11-30 m) from the population center. Chinese yam similarly tolerates full sun to partial shade but tubers are edible or palatable, yet some are of such dietary importance that they have achieved social and religious importance as well. tubers [87]. means of regeneration, stems touching the ground are capable of producing adventitious roots and tubers [46,51]. (22 m) from the center of the source population [8]. Yams are reported in full sun Growth rates In Several sources report evidence of small mammals feeding on yam bulbils ([8,77], Leaves may reach 10 inches (26 cm) wide and long; leaf petioles are generally shorter than the leaf blade [21,51,89,93]. the average number of seeds/fruit was 2.7 and 3.2. Herbicides applied to Chinese yam "later" in the season may be translocated to tubers and may result Leaves are alternate and compound with 3 to 5 leaflets. biological control program requires "great caution" (review by [66]). lobata) [55]. other vegetation for support, they can damage or kill this vegetation as well as provide ladder fuels into the canopy. Flowers are rare or restricted to a [52]. In southern Florida hammocks, herbicide treatments in areas where air yam was hand pulled were no more effective than hand pulling alone. June to September or October in the upper Midwest [15,76]. Control method did not largely affect the abundance of Chinese yam in Great Smoky Mountains National Park. Water yam may begin producing tubers 14 to 40 days after can be rapid (Copeland 1916 cited in [13]), and production of bulbils has Line 1992 personal communication cited in [66]). Early in the growing season, the previous year's In Oklahoma, Chinese yam occupies thickets and woodlands [74]. [81]. 10 inches (5-25 cm) long [89]. However, tuber shape is likely [19]. especially coastal hammocks in southern Florida (EPPC 1996 cited in [41]). Bulbils may reach 4 inches (10 cm) long and 1.5 inches (4 cm) in diameter [12,21]. Invasive Species - (Dioscorea oppositifolia) Watch List Chinese Yam has slender vines that spiral counterclockwise and pointed, heart-shaped leaves that are often indented on the sides. Mature tubers can New York [55]. conditions for tropical yams are temperatures of about 86 °F (30 °C) and growing season precipitation Disturbed sites are often occupied by yam vines [94], and vines also persist in wooded areas (Milne-Redhead 1975 cited in [82], Putz 1992 personal communication cited in [66], Impacts: Climbing habits, rapid growth Like water flowers produce a pleasant odor thought to attract bees and other insects [45], True roots are only Soils were low in potassium, high in nitrogen, phosphorus, and calcium, and very high in magnesium. In 2001, escaped populations were reported from 21 Illinois counties (review by [8]). digging are potentially useful control methods for small, newly established yam populations. Zanzibar yam leaves and petioles are long. Reviews report that mature yam bulbils float in water [13,51], For air yams, 2 to 6 inches (6-16 cm) long, 2 to 5 inches (4-13 cm) wide, and have entire margins. pathogens released to control nonnative yam species. produced bulbils, and production averaged 14.8 bulbils for each 3 feet (1 m) of stem length [77]. Both are classifed as same species and there are more than two hund… Petioles may be 10 inches (26 cm) long, and leaves often have a tail-like Once yams were introduced, cultivation was encouraged because of their food value and ability to quickly develop Although fruits can produce up to 6 seeds, In the Bearcamp Creek to the Testudinaria section (see Taxonomy). produced by seedlings, and these are short-lived. grow belowground tubers annually; perennial tubers are generally restricted to the Testudinaria section of the A 2-pound (1 kg) tuber can be divided into 112 pieces, tubers [44]. ex L.C.Beck) Fernald: Synonym: WCSP: 2012-03-23: Dioscorea quinata Walter: Synonym: WCSP: 2012-03-23: Dioscorea repanda Raf. Stems were viable. Dioscorea quaternata var. [5,78]). Air yam occurs at about sea level in Florida [21] and Although Chinese yam occupies a much larger range than the other yams, its habitats are similar. Yams are herbaceous, climbing, twining, perennial monocots [13,72,89]. There were no flowers produced on vines from bulbils, but vines from tubers did flower [44]. Researchers suggested that a lack of pollinators was the reason for poor fruit set. Chinese yam is native to eastern Asia [21]. are the most commonly described impacts of yam populations. perennial regeneration within established populations, and aerial bulbils allow for dissemination of propagules and to increase the visibility of bulbils to be collected (Gordon 1992 personal communication Sexual reproduction by yams has not been observed in the United States, where regeneration occurs exclusively through sprouting from tubers and bulbils [21,69]. medicinal uses. Cutting alone only reduced growth rates by about 10% yam is a versatile vegetable it … Leaflets measure 2 to 4 inches (5-10 cm) long and 0.8 Biological control: Currently (2009) there have been no insects or Dioscorea polystachya Turcz. populations [8]. than a tactical approach focused on battling individual invaders [42]. Weed control methods handbook [79] possession, and moving of air yam vines [3]; however, as of 1998, air yam have logged 588 hours over 8 years but believe the population will be eradicated soon, though vigilant The Asian type produces relatively smooth, spherical bulbils that may weigh 2 pounds (1 kg). Vine stems are about 1 inch (3 cm) thick and may grow to 10 inches (25 cm) or more. fragments are capable of producing new vines (Line 1992 personal communication cited in [66], but in Great Smoky Mountains National Park, it is reported from elevations of 950 to 3,300 feet (290-1,000 m) A review by Tu [78] reports that leaves may be the density of Chinese yam leaves was classified as moderate or heavy. During the and, if produced, are often sterile [21,24,61]. Dioscorea sansibarensis Pax (section Macroura), Zanzibar yam [13]. Herbicides are effective in gaining initial control of a new invasion or a severe infestation, but they are Species Description. [78]). IMPACTS AND CONTROL: One researcher noted that Chinese yam could reach 13 feet (4 m) long by early June in an area where plant species richness was significantly lower (P=0.0001) in plots with Chinese yam than in plots without Chinese yam. Flowers, when produced, occur in late summer or early fall [21]. homesteads where it was planted as early as 1900. In southern Illinois, Chinese yam occurred in closed-canopy woodlands, where canopy cover averaged 68% and light intensity averaged 8% of full sunlight [8]. Although moisture Observations and experiments in Senai, Japan, Air yams from Asia produce spherical tubers, while air yams from Africa produce irregular branching tubers [45]. for considerations on the use of herbicides in natural areas and detailed information on specific chemicals. emerge from tubers or bulbils from March to May [53,66]. United States [78]. projection at the tip [21,51,82]. Tubers from air yams in Florida were usually less than 4 inches (10 cm) in diameter but were up to 8 inches (20 cm) in diameter on vines growing in sandy soil (Gann-Matzen and Line 1992 personal communications cited in [66]). It is closely related to air potato (Dioscorea bulbifera). Leaves are deeply Altered fuel characteristics: Because yam vines use Burning of collected yam bulbils has also been recommended, since on-site destruction of bulbils should decrease the potential for dispersal and spread (review by [51]). Cover of air yams was greater than that of any native vine species [34]. 4(Heft 87): 324. In 69% of visited sites, SEASONAL DEVELOPMENT: The number of volunteers was not reported. Yam [Illegitimate] Synonym: WCSP: 2012-03-23: Dioscorea sativa L. Synonym: WCSP: 2012-03-23: Dioscorea villosa var. The leaves of air yam, Chinese yam, and water yam are used as a poultice to 8 inches (20 cm)/day and smother tree seedlings and understory vegetation (review by [51], (Oble 1995 personal communication cited in [54]). From December 2001 to February 2003, about 300 bulbils/m³ were collected from traps near the downstream boundaries Male flowers occur in bundles, spikes, or panicles at branch ends [54]). Moderate temperatures 77 to 86 °F In Great Smoky Mountains National Park, Chinese yam growth was rapid You should refer instead to the current version of The Plant List. In Florida in 1977, air yam was described as "becoming extensively naturalized". Yam seeds are winged but have not been observed in the occurs in March or early April in southern Florida ([3,53], In Florida hammocks, several herbicide treatments were compared on air yam populations. Covered with large leaves, it can quickly grow into the tops of tall trees. Native species consistently found in plots invaded by Chinese yam included Virginia creeper (Parthenocissus quinquefolia), poison-ivy (Toxicodendron radicans), Pennsylvania blackberry (Rubus pensilvanicus), and white ash (Fraxinus americana) [8]. The researcher suggested that type 2 populations were likely older and established much earlier than type 1 populations. For more 1 thin vine, while tubers produced an average of 4 robust vines. The findings from the study were used together with weather data to predict the dates at which half lasted 39 weeks, 100% of bulbils sprouted at 80 °F (27 °C), and 85% of bulbils sprouted at 60 °F During careful observation, just 1 small unidentified crawling severity, and fire frequency on postfire recovery and establishment of yams are largely unknown (as of 2009). Yams generally have Bulbil sprouts have been observed in environments without light, water, or of male pride [46]. Likewise the potential for survival of bulbils attached to the vine probably increases with increasing bulbil size and increasing vine height. review by [51]), but yams also have many medicinal and other uses Although air yams have moderate protein levels, protein quality is generally low [45]. Information on flower pollination, seed dispersal, seed banking, and germination is sparse. 1st-year Chinese yam vines from bulbils was much less than that of 2-year-old vines from tubers near Knoxville, Tennessee. This topic is discussed in Fuels and Fire Regimes. of about 59 inches (1,500 mm). Staminate flowers occur in a zig-zag pattern The underground tubers can grow very large over time; adequate size pots should be provided. During field experiments conducted in central In Hawaii, air yam is common in the moist regions of Bulbils are horseshoe shaped and about 1 cm in diameter [89]. Sprouts can develop from 2-week old bulbils (review by [78]), and small pea-sized bulbils or bulbil Spread: Increases in Chinese yam population size and range are documented for southern Illinois and Great Smoky Mountains National Park. Provide ample moisture during active growing season. When seedlings produced from these seeds were artificially pollinated, none developed seed. air yam, Chinese yam, and water yam "pose a demonstrable threat to the integrity of the natural plant communities" in the Southern Region. forest edge or in forest gaps (Overholt personal observation cited in [3]). Just 19 of 180 marked bulbils were recovered. Sprouts have developed from 2-week-old bulbils Fire has been recommended to reduce the chance of bulbil survival ([77], review by [51]) A land manager for Ohio's Edge of Appalachia Preserve Tubers grow vertically from long stalks and typically water yams were planted at staggered dates to encourage synchronous flowering and possibly natural fruit set. It is one of various species of yams that were domesticated and cultivated independently within Island Southeast Asia and New Guinea for their starchy tubers, including the round yam ( Dioscorea bulbifera ), ubi gadong ( Dioscorea hispida ), lesser yam ( Dioscorea esculenta ), Pacific yam ( Dioscorea nummularia ), fiveleaf yam ( Dioscorea pentaphylla ), and pencil yam ( Dioscorea transversa ). through rolling, traction, and saltation actions [54]. old homesteads, roadsides, fence rows, thickets, alluvial woodlands, stream banks, and canals all provide Chinese Refer to these sources: [86,91] Other researchers studying vegetation recovery in Florida hammocks The scientific name for the genus commonly known as yams is Dioscorea L. (Dioscoreaceae) [21,36]. Because yams sprout soon after cutting, repeated mowing or cutting are required to deplete tuber stores Additional information on asexual regeneration by yams is presented in This Seed production: In studies conducted in India, either hand pollination or staggered planting to encourage synchronous flowering were required for seed set in water yams. After conducting a survey of Chinese yam's distribution, habitats, and population biology, the Illinois Department There are reports of sprouts from bulbils without light, moisture, or soil contact ([3], Brinkley and Gann-Matzen 1992 Aboveground descriptions: Air yam: In Florida, the primary nonnative range for air yams, vines Growth and reproductive output of There is both speculation and evidence regarding the method and timing of yam introductions in the United States. Chinese yam not known outside of cultivation in 1970, but by 1986 was reported in disturbed areas of Jackson County. Seedlings produced few flowers and had low tuber yields [2]. vegetation, forming a blanket of leaves that shade other plants and may bend or break branches (review by near ponds, marshes, and drainage canals in Florida and Georgia [21]. effects studies on yams were uncommon in the literature (as of 2009), there are reports of sprouting from In 1977, water yam was reported as cultivated and "sparingly escaped" in Florida's Escambia, Leon, Alachua, Lee and Dade counties (Ward 1977 How to Cite, The Plant List — A working list for all plant species. It has small, white or greenish-yellow flowers that smell like cinnamon. Bulbils were rare in Hawaii according to St John [70]. review by [51]), suggesting early- to late-seral communities are potential yam habitat. southern Illinois found that secondary dispersal by water occurred along streams in the Drury Creek Watershed. the 17th century (reviews by [13,14]). Researchers found that the estimated area occupied by Chinese yam in 1995 was more than twice that occupied in 1988 [54]. Hammer [30] Water yam was likely transported to the eastern coast of Africa 2,000 years before present (review by [14]). Leaf petioles are generally as long as the leaf blade [21] Leaf arrangement appears inconsistent. Winged yam (Dioscorea alata) is another non-native, invasive vine in Florida. Flowers were observed in the field in southern Illinois from (reviews by [3,5,78]). Chinese yam occupied an estimated 161,000 feet² (15,000 m²) of Park area on 125 surveyed sites. Emergence Use of prescribed fire as a control agent: While fire alone is unlikely to control yam populations, it may improve the effectiveness of other control methods. Tuber growth averaged 0.2 cm/day [52]. Dioscorea alata L. (section Enantiophyllum), water yam times each year [35]. Zanzibar yam: Bulbils are produced by Zanzibar yams in late summer or early fall in Florida [40]; plants are not known to flower in the United States [21]. has been effective on a small air yam population in Everglades National Park. Preventing postfire establishment and spread: Preventing invasive along a rachis up to 10 inches (25 cm) long; pistillate flowers occur in 4- to 20- flowered inflorescences that may reach 14 inches (35 cm) long [21]. can decrease the time to sprout by up to 2 weeks [46]. Japan, nearly 100% of air yam and fiveleaf yam bulbils sprouted at 77 °F (25 °C), and almost all water yam bulbils sprouted at 86 °F (30 °C) [57]. Based on its US distribution, growth of air yams is best where average annual minimum temperatures do not fall below 10 °F (-12.2 °C). in the 1800s in the United States [21,69]. There are different types of yam which are found throughout the humid tropics. After water yam's introduction, it was widely cultivated. Dioscorea oppositifolia occurs only in India [21,93]. staging areas, and helibases, Clean equipment and vehicles prior to entering burned areas, Regulate or prevent human and livestock entry into burned areas until desirable site vegetation has Both belowground that water yam leaves are alternate at the stem base and opposite near the stem end [21], and phosphorus, Avoid areas dominated by high priority invasive plants when locating firelines, monitoring camps, yam tubers contain allantoin, which speeds the healing process. yams occur at the edges or in the canopy gaps of rainforests and woodlands. species, see Fire Management Considerations. In Great Smoky Mountains The use of these yams is prohibited on National Forest Service lands, Fires occurred in March, before the emergence of air yam vines. Native origins: Yams not native to North America recover by the end of the growing season (reviews by [3,78]). – Yellow yam (Dioscorea cayenensis Cavensis = D = D = D. aculeata angustiflora berteroana = D = D. occidentalis): Species native to Africa and widely cultivated in this continent. been reported on 3-month-old air yam vines [45]. Water yams are one of the most commonly cultivated yam crops. A particularly large tuber was dug from Alachua County, Florida; it was 9.8 inches (25 cm) in diameter and weighed The Plant List includes 1,192 scientific plant names of species rank for the genus Dioscorea. yam habitat throughout its range [21,43,50,54,61]. Yams often occur in mesic habitats in the United States. to have magical properties in parts of Africa, may have been brought to the United States for use in religious Growth from bulbils and tubers compared: Vegetative and reproductive potential increased dramatically once Chinese yam vines were established. Chinese yam has increased its range in northern as well as southern US habitats. leaves may grow to 4.3 inches (11 cm) long and wide [21,24]. Chinese yam: Chinese yam vine growth begins in April in Illinois, Although referred to as roots in the literature and in this review, tubers and belowground structures attached to the root crown are adventitious stem tissue [45,46]. For the results of herbicide treatments on cut stems, see generally decrease as the growing season progresses [8,52]. The growth rate of Chinese yam populations in southern Illinois decreased exponentially as the growing season progressed [8]. From May to June, vines grew an average of 1.5 inches (3.9 cm)/day and from June to August grew 1.4 inches (3.5 cm)/day. Although common in rich alluvial soils, Chinese yam also occurs in semi-xeric habitats with rocky soils of 3 Chinese yam populations, where stand density ranged from 73 to 200 vines/ha. elegantula Uline ex R.Knuth: Synonym: WCSP: 2012-03-23: Dioscorea amaranthoides var. Physical or mechanical control: Collecting bulbils, hand-pulling, and bulbils can survive fire [26], so fire must be severe enough to cause vine and bulbil mortality. (25-30 °C) are considered optimal for sprouting of water yam bulbils. In southern Illinois, Chinese yam has spread from Researchers have identified potential agents in Ghana, Malaysia, and Nepal, but no releases have occurred ([20], review by [3]). Water yam grows well in permeable clays and but vines from fragmented bulbils produced fewer bulbils in the next growing season than vines from entire Chinese yam. Click below on a thumbnail map or name for species profiles. Submerging water yam bulbils shaded valleys and disturbed forests, and fiveleaf yam is common in windward mesic valleys [89]. Nehrling's comments on the substantial growth and vigor exhibited by air yam are presented 11 pounds (5 kg) (personal observation 1992 cited in [66]). to fire damage than small bulbils. but it is unclear if air yam is native to both continents or was introduced from one to the other [51]. (Gordon 1992 personal communication cited in [66]) and on alluvial floodplains The air potato plant (Dioscorea bulbifera) is an exotic vine from Asia that was introduced to Florida about 115 years ago to make medicine. REGENERATION PROCESSES: Dioscorea bulbitera is one of the various species of yam. Water yam fruits are capsules that could produce 2 seeds per each of 3 locules, but often if 1 seed is produced it is aborted before maturity. When just 45 of the 125 original survey sites were visited in 1994 and 1995, researchers estimated that Freezing temperatures kill air yam bulbils [3]. Gardens that produce giant plants and tubers are a source Biological control of invasive species has a long history that indicates many factors must be considered Hemicryptophyte habitats, air yam occurs in loams or loose clays with good drainage (review by [3]). Herbicide treatments just before or shortly after bulbil development may reduce subsequent bulbil watershed in the western Carolinas, Chinese yam was common at homesteads abandoned around 1900 [64]. and is more likely to disrupt the native plant community. After be more "vigorous" in canopy gaps (Gordon and Putz 1992 personal communications cited personal communications cited in [66]). Soil characteristics were described for Chinese yam populations in but decreased from April to August. Fiveleaf yam tubers dug in Hawaii ranged from 1 to 6.7 inches (2.6-17 cm) long and were about Botanical description Nehrling was known for the In southern of Natural Resources reported that Chinese yam "appears to be one of the fastest spreading exotics in southern Illinois" [90]. in Impacts. introduction, promotion, and dissemination of plants for the Florida nursery trade [30]. Sexual reproduction: Because synchronous flowering, fruit production, and successful seed set are extremely rare for yams, information about sexual reproduction is limited and generally involves aritificial conditions. Monitoring near established populations could allow for earlier control of satellite populations (review by [66]). As of 2009, few successional studies in yam-invaded habitats were available. When bulbils were collected in the fall in This description covers characteristics that may be relevant to fire ecology and is not meant for If control is successful, the potential for other invasive species to fill the void left by yam removal Climate: For all but Chinese yam, sub-tropical to tropical climates are preferred, and growth is limited at temperatures below 68 °F (20 °C). Generally tubers are shallowly buried (up to 6 inches (15 cm) deep) and may logging and site preparation, grazing allotments, recreation management, research projects, road building and maintenance, and fire management [84]. sore throats, and diabetes. When stems cut to a 2-inch (5 cm) height were treated with herbicides, growth rates were reduced by 34% to 100%, depending on type of herbicide used. In the summer, flowers are occasionally produced. Known as “air potatoes,” these guys can mess you up. Weed prevention and control can be incorporated into many types of management plans, including those for Those bulbils retaining 33% of their original size were capable of sprouting [8], After the hurricane, the cover of nonnative vines was much greater on untreated than treated sites, where all nonnative This review summarizes information available as of 2009 on the following 5 yam species: Dioscorea alata L. (section Enantiophyllum), water yam Dioscorea bulbifera L. (section Opsophyton), air yam Dioscorea pentaphylla L. (section Lasiophyton), fiveleaf yam Chinese yam occurred most often in silty loams. However, some suggest that air yam may lack underground tubers [3,21]. When Zanzibar yam stems were left in a laboratory, they began producing bulbils within a week of detachment, although bulbil production and size were less than those of intact stems [62]. Bulbils are typically less than 1 inch (3 cm) long and less than 0.8 inch (2 cm) in diameter [21,47,61,69].