Editing Tuber (section)

== Stem tubers ==
[[File:Starr 010725-9001 Anredera cordifolia.jpg|thumb|upright=1.2|Flowers and tuber of ''[[Anredera cordifolia]]'']]

A stem tuber forms from thickened [[rhizome]]s or [[stolon]]s. 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 or [[tubercule]]s that act like seeds, producing small plants that resemble (in morphology and size) seedlings. Some stem tubers are long-lived, such as those of tuberous [[begonia]]s, 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.{{cn|date=October 2023}}

Stem tubers generally start off as enlargements of the [[hypocotyl]] section of a seedling, but sometimes also include the first node or two of the [[epicotyl]] and 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.{{cn|date=October 2023}}

Tuberous begonias, [[Yam (vegetable)|yams]],<ref name=FNA>{{eFloras|1|10280|Dioscoreaceae |last1=Raz |first1=Lauren |publisher=Flora of North America North of Mexico |volume=26 |url-status=live |archive-url=https://web.archive.org/web/20060419014306/http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10280 |archive-date=2006-04-19 }}</ref><ref name=Martin>{{cite journal|last1=Martin|first1=FW|last2=Ortiz|first2=Sonia|title=Origin and Anatomy of Tubers of Dioscorea Floribunda and D. Spiculiflora|journal=Botanical Gazette|date=1963|volume=124|issue=6|pages=416–421|doi=10.1086/336228|jstor=2473209|s2cid=84746878}}</ref> and cyclamens are commonly grown stem tubers. Mignonette vine (''[[Anredera cordifolia]]'') produces aerial stem tubers on {{convert|12|to|25|ft|m|adj=mid|-tall|order=flip|round=0.5}} vines; the tubers fall to the ground and grow. ''[[Plectranthus esculentus]]'', of the mint family [[Lamiaceae]], produces tuberous underground organs from the base of the stem, weighing up to {{convert|1.8|kg|lboz|abbr=on}} per tuber, forming from axillary buds producing short stolons that grow into tubers.<ref>{{cite journal|author1=J. Allemann |author2=P.J. Robbertse |author3=P.S. Hammes |date=20 June 2003 |title=Organographic and anatomical evidence that the edible storage organs of ''Plectranthus esculentus'' N.E.Br. (Lamiaceae) are stem tubers |journal=Field Crops Research |volume=83 |issue=1 |pages=35–39 |doi=10.1016/S0378-4290(03)00054-6 |bibcode=2003FCrRe..83...35A }}</ref> Even though [[legume]]s are not commonly associated with forming stem tubers, ''[[Lathyrus tuberosus]]'' is an example native to Asia and Europe, where it was once grown as a crop.<ref name="Mansfeld2001" />

===Potatoes===
{{Main|Potato}}
[[File:SolanumTuberosumYoungTuber.jpg|thumb|A young [[potato]] tuber]]

Potatoes are stem tubers{{snd}}enlarged stolons thicken to develop into [[storage organ]]s.<ref>{{cite web |url=http://potatogenome.berkeley.edu/nsf5/potato_biology/tuber_formation.php |title=Potato Genome Project |author=University of California, Berkeley |author-link=University of California, Berkeley |access-date=17 July 2018 |archive-date=15 July 2010 |archive-url=https://web.archive.org/web/20100715200630/http://potatogenome.berkeley.edu/nsf5/potato_biology/tuber_formation.php |url-status=dead }}</ref><ref>"Interrelationships of the number of initial sprouts, stems, stolons and tubers per potato plant" ''Journal Potato Research''. Springer Netherlands {{ISSN|0014-3065}} (Print) {{ISSN|1871-4528}} (Online) Volume 33, Number 2 / June 1990</ref><ref>{{cite web |url=http://www.personal.psu.edu/faculty/w/x/wxm15/Online/Botany/Stems/stem_lecture_01.htm |title=Introduction to Stems |access-date=2005-05-10 |url-status=dead |archive-url=https://web.archive.org/web/20050413012738/http://www.personal.psu.edu/faculty/w/x/wxm15/Online/Botany/Stems/stem_lecture_01.htm |archive-date=2005-04-13 | website = Pennsylvania State University - Environmental Science | publisher = Monaco Educational Service | date = 2000}}</ref> 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 same [[apical dominance]] as a normal stem. Internally, a tuber is filled with starch stored in enlarged [[parenchyma]]-like cells. The inside of a tuber has the typical cell structures of any stem, including a pith, vascular zones, and a cortex.{{cn|date=October 2023}}

The tuber is produced in one growing season and used to [[perennate]] the plant and as a means of [[Plant propagation|propagation]]. 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 long [[etiolation|etiolated]] stems. The stolon elongates during long days with the presence of high [[auxins]] levels 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.{{cn|date=October 2023}}

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.{{cn|date=October 2023}}

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