Editing Welwitschia (section)

==Description==
After [[germination]], the seedling produces two [[cotyledon]]s which grow to {{Convert|25–35|mm||abbr=on}} in length.<ref name=Singh>{{cite book|last1=Singh|first1=V.P.|title=Gymnosperm (naked seeds plant) : structure and development|date=2006|publisher=Sarup & Sons|isbn=978-8176256711|page=576|url=https://books.google.com/books?id=F6B_xHO-IpoC&q=Welwitschia+cotyledons&pg=PA576|access-date=24 January 2016}}</ref> They start off as pink, but turn green shortly after germination. Subsequently, two permanent [[Leaf|leaves]] emerge from the crown (large, woody [[Plant stem|stem]]) and are produced opposite (at right angles) to the cotyledons. The permanent leaves grow rapidly and last for the plant's entire life. They are long and ribbon-shaped, with their [[Vascular plant|veins]] running down their length parallel to each other.<ref name="PlantZAfrica" /><ref name="Bornman" /> Shortly after the appearance of the permanent leaves, the [[meristem#Apical meristems|apical meristem]] dies and meristematic activity is transferred to the periphery of the crown.<ref name=Bornman>{{cite book|last=Bornman|first=Chris&nbsp;H|date=1 January 1978|title=Welwitschia: Paradox of a parched paradise|location=Cape Town|publisher=C&nbsp;Struik|isbn=9780869770979}}</ref> The two (rarely three) leaves grow continuously from the crown across its entire circumference, reaching lengths up to {{Convert|4|m||abbr=on}}. The crown is disc-shaped and widens with age, reaching up to a meter in diameter.<ref name=":0" /> The largest specimens may be no more than {{Convert|1.5|m|ft|abbr=on}} tall above ground, but the circumference of the leaves in contact with the sand may exceed {{Convert|8|m|ft|abbr=on}}.<ref name="Bornman et al 72">{{cite journal |last1=Bornman |first1=Chris&nbsp;H |last2=Elsworthy |first2=Janet&nbsp;A |last3=Butler |first3=Valerie |last4=Botha |first4=C&nbsp;E&nbsp;J |date=1 January 1972 |title=''Welwitschia mirabilis'': observations on general habit, seed, seedling, and leaf characteristics |url=https://journals.co.za/doi/10.10520/AJA10115498_46 |journal=Madoqua Series II |volume=1 |issue=1 |pages=53–66 |access-date=21 July 2023}}</ref> The largest known individual is {{Convert|2.77|m|ft}} in diameter and {{Convert|8.7|m||abbr=on}} in circumference.<ref name="Bornman" /> As the plant ages, the leaves often split into ribbons and become frayed from years of weathering.<ref name="PlantZAfrica" /><ref name=":0" /> The age of individual plants is difficult to assess, with [[radiocarbon dating]] is the most common method in determining plant age.<ref>{{Gymnosperm Database|family=Welwitschiaceae|title=''Welwitschia mirabilis''|access-date=21 July 2023|quote=Although ''Welwitschia'' produces no growth rings, radiocarbon dating is feasible and results have indicated maximum ages in excess of 1,500 years.}}</ref> The plant is exceptionaly long-lived, with many being hundreds of years old,<ref>{{Cite journal |last=Henschel |first=Joh R. |last2=Seely |first2=Mary K. |date=2000-10-01 |title=Long-term growth patterns of Welwitschia mirabilis, a long-lived plant of the Namib Desert (including a bibliography) |url=https://link.springer.com/article/10.1023/A:1026512608982 |journal=Plant Ecology |language=en |volume=150 |issue=1 |pages=7–26 |doi=10.1023/A:1026512608982 |issn=1573-5052}}</ref> and the oldest being potentially up to 2,000.<ref name="Bornman" /><ref name=":1" />

''Welwitschia'' is [[dioecious]], with separate male and female plants. Both sexes produce cones that grow out of the crown of the plant, which often number in the hundreds.<ref name="Wetschnig and Depisch" /> Cones can range from green to [[Salmon (color)|salmon]] to various shades of brown in color.<ref name=":0" /><ref>{{Cite web |title=The two subspecies of Welwitschia mirabilis |url=https://www.bgbm.org/en/two-subspecies-welwitschia-mirabilis |website=Freie Universität Berlin}}</ref> The cones produce nectar that atracts various insects, most commonly [[Fly|flies]], that then carry the oval-shaped pollen on them. The Welwitschia bug, [[Probergrothius angolensis|''Probergrothius angolensis'']], is commonly observed on the plant, but likely does not have a role in pollination; they are not particularly atracted to the nectar and are usually found on the leaves of the plant. Infrequently, wasps and bees also play a role as [[pollinator]]s of ''Welwitschia.''<ref name="Wetschnig and Depisch">{{cite journal|author=Wetschnig W, Depisch B|year= 1999|title=[Chrysomya albiceps Pollination biology of ''Welwitschia mirabilis'' HOOK. f. (Welwitschiaceae, Gnetopsida)]|journal=Phyton: Annales Rei Botanicae|volume=39|pages=167|url=http://www.zobodat.at/pdf/PHY_39_1_0167-0183.pdf}}</ref>

[[File:Stem of a Welwitschia which according to a C14 test was far more then 1000 years old on display at the Swakopmund Museum, Namibia.jpg|thumb|Stem of a ''Welwitschia'', which according to a C14 test was more than 1,000 years old, on display at the Swakopmund Museum, Namibia.]]

Because ''Welwitschia'' only produces a single pair of leaves, the plant was thought by some to be [[neoteny|neotenic]], consisting essentially of a "giant [[seedling]]." However, research showed that its anatomy is not consistent with a "giant seedling". Instead, the plant is more accurately thought to achieve its unusual morphology as a result of having "lost its head" (apical meristem) at an early stage.<ref>{{cite journal|jstor=2442386|title=Welwitschia mirabilis and Neoteny|first=P.|last=Martens|date=4 September 1977|journal=American Journal of Botany|volume=64|issue=7|pages=916–920|doi=10.2307/2442386}}</ref>