Tuber

Tubersare a type of enlarged structure thatplantsuse asstorage organsfornutrients,derived from stems or roots. Tubers help plantsperennate(survive winter or dry months), provide energy and nutrients, and are a means ofasexual reproduction.^[1]

Stem tubersmanifest as thickenedrhizomes(underground stems) orstolons(horizontal connections between organisms); examples include thepotatoandyam.The termroot tuberdescribes modified lateralroots,as insweet potatoes,cassava,anddahlias.

Terminology

The term originates from theLatintuber,meaning 'lump, bump, or swelling'.^[2]

Some writers limit the definition oftuberto structures derived fromstems,^[3]while others apply the termroot tuberto structures derived fromroots.^[4]

Stem tubers

Astem tuberforms from thickenedrhizomesorstolons.The top sides of the tuber produce shoots that grow into typical stems and leaves and the undersides produce roots. They tend to form at the sides of the parent plant and are most often located near the soil surface. The underground tuber is normally a short-lived storage and regenerative organ developing from a shoot that branches off a mature plant. The offspring or new tubers are attached to a parent tuber or form at the end of a hypogeogenous (initiated below ground) rhizome. In the autumn the plant dies, except for the new offspring tubers, which have one dominant bud that in spring regrows a new shoot producing stems and leaves; in summer the tubers decay and new tubers begin to grow. Some plants also form smaller tubers ortuberculesthat act like seeds, producing small plants that resemble (in morphology and size) seedlings. Some stem tubers are long-lived, such as those of tuberousbegonias,but many plants have tubers that survive only until the plants have fully leafed out, at which point the tuber is reduced to a shriveled-up husk.^{[citation needed]}

Stem tubers generally start off as enlargements of thehypocotylsection of a seedling, but sometimes also include the first node or two of theepicotyland the upper section of the root. The tuber has a vertical orientation, with one or a few vegetative buds on the top and fibrous roots produced on the bottom from a basal section. Typically the tuber has an oblong rounded shape.^{[citation needed]}

Tuberous begonias,yams,^[5]^[6]and cyclamens are commonly grown stem tubers. Mignonette vine (Anredera cordifolia) produces aerial stem tubers on 3.5-to-7.5-metre-tall (12 to 25 ft) vines; the tubers fall to the ground and grow.Plectranthus esculentus,of the mint familyLamiaceae,produces tuberous underground organs from the base of the stem, weighing up to 1.8 kg (3 lb 15 oz) per tuber, forming from axillary buds producing short stolons that grow into tubers.^[7]Even thoughlegumesare not commonly associated with forming stem tubers,Lathyrus tuberosusis an example native to Asia and Europe, where it was once grown as a crop.^[8]

Potatoes

Potatoes are stem tubers – enlarged stolons thicken to develop intostorage organs.^[9]^[10]^[11]The tuber has all the parts of a normal stem, including nodes and internodes. The nodes are the eyes and each has a leaf scar. The nodes or eyes are arranged around the tuber in a spiral fashion beginning on the end opposite the attachment point to the stolon. The terminal bud is produced at the farthest point away from the stolon attachment and tubers, and thus show the sameapical dominanceas a normal stem. Internally, a tuber is filled with starch stored in enlargedparenchyma-like cells. The inside of a tuber has the typical cell structures of any stem, including a pith, vascular zones, and a cortex.^{[citation needed]}

The tuber is produced in one growing season and used toperennatethe plant and as a means ofpropagation.When fall comes, the above-ground structure of the plant dies, but the tubers survive underground over winter until spring, when they regenerate new shoots that use the stored food in the tuber to grow. As the main shoot develops from the tuber, the base of the shoot close to the tuber produces adventitious roots and lateral buds on the shoot. The shoot also produces stolons that are longetiolatedstems. The stolon elongates during long days with the presence of highauxinslevels that prevent root growth off of the stolon. Before new tuber formation begins, the stolon must be a certain age. The enzyme lipoxygenase makes a hormone,jasmonic acid,which is involved in the control of potato tuber development.^{[citation needed]}

The stolons are easily recognized when potato plants are grown from seeds. As the plants grow, stolons are produced around the soil surface from the nodes. The tubers form close to the soil surface and sometimes even on top of the ground. When potatoes are cultivated, the tubers are cut into pieces and planted much deeper into the soil. Planting the pieces deeper creates more area for the plants to generate the tubers and their size increases. The pieces sprout shoots that grow to the surface. These shoots are rhizome-like and generate short stolons from the nodes while in the ground. When the shoots reach the soil surface, they produce roots and shoots that grow into the green plant.^{[citation needed]}

Root tubers

Atuberous rootor storage root is a modified lateralroot,enlarged to function as astorage organ.The enlarged area of the tuber can be produced at the end or middle of a root or involve the entire root. It is thus different in origin, but similar in function and appearance, to a stem tuber. Plants with tuberous roots include thesweet potato(Ipomoea batatas),cassava,dahlia,andSagittaria(arrowhead) species.^{[citation needed]}

Root tubers are perennating organs, thickened roots that store nutrients over periods when the plant cannot actively grow, thus permitting survival from one year to the next. The massive enlargement of secondary roots typically represented by sweet potato have the internal and external cell and tissue structures of a normal root; they produceadventitious rootsand stems, which again produce adventitious roots.^[12]

In root tubers, there are no nodes and internodes or reduced leaves. The proximal end of the tuber, which was attached to the old plant, has crown tissue that produces buds which grow into new stems and foliage.^[13]The distal end of the tuber normally produces unmodified roots. In stem tubers the order is reversed, with the distal end producing stems. Tuberous roots are biennial in duration: the plant produces tubers the first year, and at the end of the growing season, the shoots often die, leaving the newly generated tubers; the next growing season, the tubers produce new shoots. As the shoots of the new plant grow, the stored reserves of the tuber are consumed in the production of new roots, stems, and reproductive organs; any remaining root tissue dies concurrently to the plant's regeneration of the next generation of tubers.^{[citation needed]}

Hemerocallis fulva(orange daylily) and a number ofdaylilyhybrids have large root tubers;H. fulvaspreads by underground stolons^[14]that end with a new fan that grows roots that produce thick tubers and then send out more stolons.^[8]^[15]

Plants with root tubers can be propagated from late summer to late winter by digging up the tubers and separating them, making sure that each piece has some crown tissue for replanting.^{[citation needed]}

Root tubers are a rich source of nutrients for humans and wild animals, e.g. those ofSagittariaplants which are eaten by ducks.^[16]

References

^Rooting Cuttings of Tropical Trees,London: Commonwealth Science Council, 1994, p. 11,ISBN 978-0-85092-394-0
^"Tuber".Online Etymology Dictionary.Archivedfrom the original on 2016-02-15.
^Mauseth, James D. (2012),Botany: An Introduction to Plant Biology(5th ed.), Sudbury, MA: Jones and Bartlett Learning,ISBN 978-1-4496-6580-7,p. 672
^Beentje, Henk (2010),The Kew Plant Glossary,Richmond, Surrey:Royal Botanic Gardens, Kew,ISBN 978-1-84246-422-9,p. 124
^Raz, Lauren (2002)."Dioscoreaceae".In Flora of North America Editorial Committee (ed.).Flora of North America North of Mexico (FNA).Vol. 26. New York and Oxford: Flora of North America North of Mexico.Archivedfrom the original on 2006-04-19 – via eFloras.org,Missouri Botanical Garden,St. Louis, MO &Harvard University Herbaria,Cambridge, MA.
^Martin, FW; Ortiz, Sonia (1963). "Origin and Anatomy of Tubers of Dioscorea Floribunda and D. Spiculiflora".Botanical Gazette.124(6): 416–421.doi:10.1086/336228.JSTOR 2473209.S2CID 84746878.
^J. Allemann; P.J. Robbertse; P.S. Hammes (20 June 2003). "Organographic and anatomical evidence that the edible storage organs ofPlectranthus esculentusN.E.Br. (Lamiaceae) are stem tubers ".Field Crops Research.83(1): 35–39.doi:10.1016/S0378-4290(03)00054-6.
^^a ^bMansfeld, Rudolf (2001),Mansfeld's Encyclopedia of Agricultural and Horticultural Crops,Berlin: Springer, p. 2231,ISBN 978-3-540-41017-1
^University of California, Berkeley."Potato Genome Project".Archived fromthe originalon 15 July 2010.Retrieved17 July2018.
^"Interrelationships of the number of initial sprouts, stems, stolons and tubers per potato plant"Journal Potato Research.Springer NetherlandsISSN 0014-3065(Print)ISSN 1871-4528(Online) Volume 33, Number 2 / June 1990
^"Introduction to Stems".Pennsylvania State University - Environmental Science.Monaco Educational Service. 2000. Archived fromthe originalon 2005-04-13.Retrieved2005-05-10.
^Davis, Tim D.; Haissig, Bruce E., eds. (1994),Biology of Adventitious Root Formation,New York: Plenum Press, p. 17,ISBN 978-0-306-44627-6
^Kyte, Lydiane; Kleyn, John (1996),Plants from Test Tubes: An Introduction to Micropropagation,Portland, Or.: Timber Press, pp. 23–24,ISBN 978-0-88192-361-2
^Chen, Xinqi; Noguchi, Junko."Hemerocallis fulva".Flora of China.Vol. 24.Archivedfrom the original on 14 November 2016.Retrieved27 April2018– via eFloras.org,Missouri Botanical Garden,St. Louis, MO &Harvard University Herbaria,Cambridge, MA.
^http://sain.utk.edu/invasives/species32.shtml^{[permanent dead link]}
^Hammerson, Geoffrey A. (2004),Connecticut Wildlife: Biodiversity, Natural History, and Conservation,Hanover: University Press of New England, p. 89,ISBN 978-1-58465-369-1
^Davis, P.H.; Cullen, J. (1979),The Identification of Flowering Plant Families, including a Key to those Native and Cultivated in North Temperate Regions,Cambridge: Cambridge University Press, p. 102,ISBN 978-0-521-29359-4

External links

Cook's Thesaurushas a good inventory of tuber varieties.
CGIAR Research Program on Roots, Tubers and Bananas

[rooting_cuttings_of_tropical_trees-1] Rooting Cuttings of Tropical Trees,London: Commonwealth Science Council, 1994, p. 11,ISBN 978-0-85092-394-0

[2] "Tuber".Online Etymology Dictionary.Archivedfrom the original on 2016-02-15.

[3] Mauseth, James D. (2012),Botany: An Introduction to Plant Biology(5th ed.), Sudbury, MA: Jones and Bartlett Learning,ISBN 978-1-4496-6580-7,p. 672

[Been10-4] Beentje, Henk (2010),The Kew Plant Glossary,Richmond, Surrey:Royal Botanic Gardens, Kew,ISBN 978-1-84246-422-9,p. 124

[FNA-5] Raz, Lauren (2002)."Dioscoreaceae".In Flora of North America Editorial Committee (ed.).Flora of North America North of Mexico (FNA).Vol. 26. New York and Oxford: Flora of North America North of Mexico.Archivedfrom the original on 2006-04-19 – via eFloras.org,Missouri Botanical Garden,St. Louis, MO &Harvard University Herbaria,Cambridge, MA.

[Martin-6] Martin, FW; Ortiz, Sonia (1963). "Origin and Anatomy of Tubers of Dioscorea Floribunda and D. Spiculiflora".Botanical Gazette.124(6): 416–421.doi:10.1086/336228.JSTOR 2473209.S2CID 84746878.

[7] J. Allemann; P.J. Robbertse; P.S. Hammes (20 June 2003). "Organographic and anatomical evidence that the edible storage organs ofPlectranthus esculentusN.E.Br. (Lamiaceae) are stem tubers ".Field Crops Research.83(1): 35–39.doi:10.1016/S0378-4290(03)00054-6.

[Mansfeld2001-8] Mansfeld, Rudolf (2001),Mansfeld's Encyclopedia of Agricultural and Horticultural Crops,Berlin: Springer, p. 2231,ISBN 978-3-540-41017-1

[9] University of California, Berkeley."Potato Genome Project".Archived fromthe originalon 15 July 2010.Retrieved17 July2018.

[10] "Interrelationships of the number of initial sprouts, stems, stolons and tubers per potato plant"Journal Potato Research.Springer NetherlandsISSN 0014-3065(Print)ISSN 1871-4528(Online) Volume 33, Number 2 / June 1990

[11] "Introduction to Stems".Pennsylvania State University - Environmental Science.Monaco Educational Service. 2000. Archived fromthe originalon 2005-04-13.Retrieved2005-05-10.

[Davis1994-12] Davis, Tim D.; Haissig, Bruce E., eds. (1994),Biology of Adventitious Root Formation,New York: Plenum Press, p. 17,ISBN 978-0-306-44627-6

[Kyte1996-13] Kyte, Lydiane; Kleyn, John (1996),Plants from Test Tubes: An Introduction to Micropropagation,Portland, Or.: Timber Press, pp. 23–24,ISBN 978-0-88192-361-2

[14] Chen, Xinqi; Noguchi, Junko."Hemerocallis fulva".Flora of China.Vol. 24.Archivedfrom the original on 14 November 2016.Retrieved27 April2018– via eFloras.org,Missouri Botanical Garden,St. Louis, MO &Harvard University Herbaria,Cambridge, MA.

[15] ttp://sain.utk.edu/invasives/species32.shtml^{[permanent dead link]}

[Hammerson2004-16] Hammerson, Geoffrey A. (2004),Connecticut Wildlife: Biodiversity, Natural History, and Conservation,Hanover: University Press of New England, p. 89,ISBN 978-1-58465-369-1

[Davis1979-17] Davis, P.H.; Cullen, J. (1979),The Identification of Flowering Plant Families, including a Key to those Native and Cultivated in North Temperate Regions,Cambridge: Cambridge University Press, p. 102,ISBN 978-0-521-29359-4

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