Editing Dryas octopetala

{{Short description|Species of flowering plant}}
{{Speciesbox
|image = Dryas octopetala LC0327.jpg
|genus = Dryas (plant)
|species = octopetala
|authority = [[Carl Linnaeus|L.]]
|range_map = Dryas octopetala distribution.svg
|range_map_caption = Global distribution
|synonyms_ref = <ref name="POWO">{{cite web | url = https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:724675-1 | author=Govaerts R | website = Plants of the World Online | title = ''Dryas octopetala'' L. | publisher=Board of Trustees of the Royal Botanic Gardens, Kew | access-date = 14 December 2020}}</ref>
|synonyms =
{{Collapsible list
|title = Synonyms list
|
* ''Dryadaea octopetala'' <small>(L.) Kuntze</small>
* ''Dryas ajanensis'' <small>Juz.</small>
* ''Dryas alaskensis'' <small>Porsild</small>
* ''Dryas alpina'' <small>Salisb.</small>
* ''Dryas babingtoniana'' <small>A.E.Porsild</small>
* ''Dryas caucasica'' <small>Juz.</small>
* ''Dryas caucasica'' <small>Juz. ex Woronow</small>
* ''Dryas chamaedrifolia'' <small>(Crantz) Gray</small>
* ''Dryas chamaedrifolioides'' <small>Pall.</small>
* ''Dryas chamaedryoides'' <small>Pall.</small>
* ''Dryas crenata'' <small>Raf.</small>
* ''Dryas depressa'' <small>(Bab.) Bab.</small>
* ''Dryas eriopoda'' <small>Gand.</small>
* ''Dryas henricae'' <small>auct.</small>
* ''Dryas hookeriana'' <small>Juz.</small>
* ''Dryas incanescens'' <small>Juz.</small>
* ''Dryas incisa'' <small>auct.</small>
* ''Dryas lanata'' <small>Stein ex Correvon</small>
* ''Dryas lepida'' <small>Gand.</small>
* ''Dryas montana'' <small>Bubani</small>
* ''Dryas nervosa'' <small>Juz.</small>
* ''Dryas nivea'' <small>F.Kern. ex Correvon</small>
* ''Dryas octopetala'' var. ''angustifolia'' <small>C.L.Hitchc.</small>
* ''Dryas octopetala'' var. ''camschatica'' <small>(Juz.) Hultén</small>
* ''Dryas octopetala'' var. ''depressa'' <small>Bab.</small>
* ''Dryas octopetala'' f. ''hirsuta'' <small>Hartz</small>
* ''Dryas octopetala'' var. ''luteola'' <small>Hultén</small>
* ''Dryas octopetala'' subsp. ''punctata'' <small>(Juz.) Hultén</small>
* ''Dryas octopetala'' subsp. ''subincisa'' <small>Jurtzev</small>
* ''Dryas octopetala'' var. ''viscida'' <small>Hultén</small>
* ''Dryas octopetala'' subsp. ''viscida'' <small>(Hultén) Kozhevn.</small>
* ''Dryas pentaphyllaea'' <small>Hill</small>
* ''Dryas punctata'' <small>Juz.</small>
* ''Dryas punctata'' var. ''cinerea'' <small>Jurtzev</small>
* ''Dryas punctata'' var. ''kamtschatica'' <small>(Juz.) Kozhevn.</small>
* ''Dryas subincisa'' <small>(Jurtzev) Tzvelev</small>
* ''Dryas subincisa'' var. ''minor'' <small>(Hook.) Tzvelev</small>
* ''Dryas tschonoskii'' <small>Juz.</small>
* ''Dryas vagans'' <small>Juz.</small>
* ''Geum chamaedrifolium'' <small>Crantz</small>
* ''Geum octopetalum'' <small>(L.) E.H.L.Krause</small>
* ''Ptilotum octopetalum'' <small>(L.) Dulac</small>
}}
}}
'''''Dryas octopetala''''', the '''mountain avens''',<ref name=BSBI07>{{BSBI 2007 |access-date=2014-10-17}}</ref> '''eightpetal mountain-avens''', '''white dryas''' or '''white dryad''',<ref>{{Grin}}</ref> is an [[Arctic–alpine]] [[flowering plant]] in the [[family (biology)|family]] [[Rosaceae]]. It is a small [[Prostrate shrub|prostrate]] [[evergreen]] [[subshrub]] forming large colonies. The [[specific name (botany)|specific epithet]] ''octopetala'' derives from [[Greek language|Greek]] ''octo'' 'eight' and ''petalon'' '[[petal]]', referring to the eight petals of the flower, an unusual number in the Rosaceae, where five is the normal number. However, flowers with up to 16 petals also occur naturally.

As a [[floral emblem]], it is the official territorial flower of the [[Northwest Territories]] and the national flower of [[Iceland]].

==Description==
The stems are woody, tortuous, with short, horizontal rooting branches. The [[Leaf|leaves]] are glabrous above, densely white-[[tomentose]] beneath. The [[flower]]s are produced on stalks {{convert|3|-|10|cm|in|frac=2|abbr=on}} long, and have eight creamy white petals – hence the [[Botanical name#Binary name|specific epithet]] ''octopetala''.<ref name=RHSLG>{{cite book|last=Harrison|first=Lorraine|title=RHS Latin for gardeners|year=2012|publisher=Mitchell Beazley|location=United Kingdom|isbn=9781845337315|pages=224}}</ref> The style is persistent on the [[fruit]] with white feathery hairs, functioning as a wind-dispersal agent. The  feathery hairs of the seed head first appear twisted together and glossy before spreading out to an expanded ball which the wind quickly disperses.

==Distribution and habitat==
''Dryas octopetala'' has a widespread occurrence throughout mountainous areas where it is generally restricted to limestone outcrops. These include the entire [[Arctic]], as well as the mountains of [[Scandinavia]], [[Iceland]], the [[Alps]], the [[Carpathian Mountains]], the [[Balkans]], the [[Caucasus]], and in isolated locations elsewhere. In [[Great Britain]], it occurs in the [[Pennines]] of [[Northern England]], at two locations in the [[Snowdonia]] region of  [[North Wales]], and more widely in the [[Scottish Highlands]]. In [[Ireland]], it occurs on [[The Burren]] and a few other sites. In [[North America]], it is found in [[Alaska]], most frequently on previously glaciated terrain, and through the [[Canadian Rockies]]<ref>{{cite web|url=http://www.plantsofcanada.info.gc.ca/taxa.php?lang=e&gid=1001748|title=Plants of Canada Database - Dryas octopetala|publisher=Government of Canada|access-date=21 February 2016|url-status=dead|archive-url=https://web.archive.org/web/20160307180350/http://www.plantsofcanada.info.gc.ca/taxa.php?lang=e&gid=1001748|archive-date=7 March 2016}}</ref> reaching as far south as [[Colorado]] in the [[Rocky Mountains]].
It grows in dry localities where snow melts early, on gravel and rocky barrens, forming a distinct heath community on calcareous [[soil]]s.

==Climatology==
The [[Younger Dryas]], [[Older Dryas]] and [[Oldest Dryas]] [[stadial]]s are named after ''Dryas octopetala'', because of the great quantities of its [[pollen]] found in cores dating from those times. During these cold spells, ''Dryas octopetala'' was much more widely distributed than it is today, as large parts of the [[Northern Hemisphere]] that are now covered by [[forest]]s were replaced in the cold periods by [[tundra]].

==Cultivation==
''D. octopetala'' is cultivated in [[temperateness|temperate]] regions as [[groundcover]], or as an alpine or [[rock garden]] plant. It has gained the [[Royal Horticultural Society]]'s [[Award of Garden Merit]].<ref>{{cite web|title=''Dryas octopetala''|url=https://www.rhs.org.uk/Plants/6152/Dryas-octopetala/Details|publisher=Royal Horticultural Society|access-date=16 February 2020}}</ref><ref>{{cite web  | url= https://www.rhs.org.uk/plants/pdfs/agm-lists/agm-ornamentals.pdf | title = AGM Plants - Ornamental | date = July 2017 | page = 33 | publisher = Royal Horticultural Society | access-date = 6 February 2018}}</ref> The leaves are occasionally used as an herbal tea.

==Gallery==
<gallery mode="packed">
Image:Weiße Silberwurz (Dryas octopetala) 2.jpg
Image:Dryas octopetala seed head.jpg|Seed head
Image:Weiße Silberwurz (Dryas octopetala) 1.jpg
</gallery>

==References==
{{Reflist}}

==Further reading==
{{Commons}}
*{{cite journal|last=Elkington|first=T. T.|year=1971|title=''Dryas Octopetala'' L.|journal=Journal of Ecology|volume=59 |issue=3|pages=887–905|doi=10.2307/2258146|jstor=2258146|bibcode=1971JEcol..59..887E }}
*{{cite journal|last=Fisher|first=P. J.|year=1995|title=Fungal Endophytes of ''Dryas octopetala'' from a High Arctic Polar Semidesert and from the Swiss Alps|journal=Mycologia|volume=87|issue=3|pages=319–323|doi=10.2307/3760828|jstor=3760828|display-authors=etal}}
*{{cite journal|last=Skrede|first=Inger|year=2006|title=Refugia, differentiation and postglacial migration in arctic-alpine Eurasia, exemplified by the mountain avens (''Dryas octopetala'' L.)|journal=Molecular Ecology|volume=15|issue=7|pages=1827–1840 |doi=10.1111/j.1365-294X.2006.02908.x|pmid=16689901|bibcode=2006MolEc..15.1827S |s2cid=44667191|display-authors=etal}}
* {{PFAF|Dryas octopetala}}
* {{CalPhotos|Dryas|octopetala}}

{{Floral Emblems of Canada}}
{{Taxonbar|from=Q161621}}

[[Category:Dryas octopetala| ]]
[[Category:Dryas (plant)]]
[[Category:Alpine flora]]
[[Category:Flora of the Arctic]]
[[Category:Flora of Europe]]
[[Category:Flora of the Alps]]
[[Category:Flora of the Carpathians]]
[[Category:Flora of the Caucasus]]
[[Category:Flora of the Northwestern United States]]
[[Category:Flora of Subarctic America]]
[[Category:Flora of Western Canada]]
[[Category:Plants described in 1753]]
[[Category:Taxa named by Carl Linnaeus]]
[[Category:Subshrubs]]
[[Category:Flora without expected TNC conservation status]]