{{Short description|Species of flowering plant}} {{Speciesbox | image = Phyllodoce caerulea LC0329.jpg | status = G5 | status_system = TNC | status_ref = <ref name="NatureServe">{{Cite NatureServe |date=26 August 2016 |id=2.160666 |title=''Phyllodoce caerulea'' |access-date=17 January 2026}}</ref> | genus = Phyllodoce (plant) | species = caerulea | authority = (L.) Bab. | synonyms = *''Andromeda caerulea'' <small>L.</small> *''Menziesia caerulea'' <small>(L.) Sw.</small> *''Bryanthus caeruleus'' <small>(L.) Dippel</small> | synonyms_ref = &nbsp;<ref name="Coker"/><ref name="Iberica">{{cite book |author=L. Villar |year=2003 |chapter=''Phyllodoce'' Salisb. |page=512 |series=Flora Iberica |volume=4 |title=Cruciferae–Monotropaceae |editor=S. Castroviejo |publisher=Consejo Superior de Investigaciones Científicas |isbn=9788400073855 |url=http://www.floraiberica.es/floraiberica/texto/pdfs/04_074_05_Phyllodoce.pdf }}</ref> }}

'''''Phyllodoce caerulea''''', known as '''blue heath''' in British English<ref>{{cite book |author=Clive A. Stace |author-link=Clive A. Stace |year=2010 |chapter=''Phyllodoce'' Salisb. – Blue Heath |page=[https://archive.org/details/newflorabritishi00stac/page/n561 526] |title=New Flora of the British Isles |url=https://archive.org/details/newflorabritishi00stac |url-access=limited |edition=3rd |publisher=Cambridge University Press |isbn=978-0-521-70772-5}}</ref> and '''purple mountain heather'''<ref name="FNA"/> or '''blue mountainheath'''<ref>{{cite book |editor1-last=Lee |editor1-first=Sangtae |editor2-last=Chang |editor2-first=Kae Sun |title=English Names for Korean Native Plants |year=2015 |publisher=Korea National Arboretum |location=Pocheon |isbn=978-89-97450-98-5 |page=571 |url=http://www.forest.go.kr/kna/special/download/English_Names_for_Korean_Native_Plants.pdf |access-date=7 March 2019 |via=Korea Forest Service}}</ref><ref>{{PLANTS|id=PHCA10|taxon=Phyllodoce caerulea|accessdate=30 September 2015}}</ref> in American English, is an evergreen species of dwarf shrub that grows up to around {{convert|15|cm|0|abbr=on}} tall, and bears clusters of 2–6 purple flowers. It is native to boreal regions around the Northern Hemisphere, but with large gaps in its distribution.

==Description== ''Phyllodoce caerulea'' is a low shrub, typically growing {{convert|5|-|15|cm|0}} high, and exceptionally reaching {{convert|25|cm|0|abbr=on}}.<ref name="Coker"/> Its evergreen leaves are {{convert|4|-|10|mm|abbr=on}} long and {{convert|1.7|-|3.6|mm|2|abbr=on}} wide, and are borne on {{convert|1|mm|2|adj=on}} long petioles; they are arranged alternately.<ref name="Coker"/>

The flowers are borne in clusters of 2–6; each flower is {{convert|8|-|12|mm|1|abbr=on}} long, with a corolla composed of five fused petals that begin purple, but fade to a bluish pink.<ref name="Coker"/> These are surrounded by five sepals, and themselves surround the 8–10 free stamens and a superior ovary that produces nectar at its base.<ref name="Coker"/>

==Distribution== ''Phyllodoce caerulea'' has a patchy circumboreal distribution, with gaps between 110°&nbsp;W and 155°&nbsp;W and between 70°&nbsp;E and 125°&nbsp;E.<ref name="Coker">{{cite journal |author1=P. D. Coker |author2=A. M. Coker |name-list-style=amp |year=1973 |title=''Phyllodoce caerulea'' (L.) Bab. <!--|work=Biological Flora of the British Isles -->|journal=Journal of Ecology |volume=61 |issue=3 |pages=901–913 |doi=10.2307/2258657 |jstor=2258657}}</ref>

[[File:The Sow of Atholl from the A9 road.jpg|thumb|The Sow of Atholl from the north, including the site where ''P.&nbsp;caerulea'' was first discovered in the British Isles, in 1810.]] In Europe, ''P.&nbsp;caerulea'' is found from Iceland to the Kanin Peninsula.<ref name="Coker"/> Its Icelandic distribution is also disjunct, comprising the area around Eyjafjörður and a site near Desjarmyri.<ref name="Coker"/> In the British Isles, ''P.&nbsp;caerulea'' is confined to a few sites in the Scottish Highlands. It was first discovered around a spring at an altitude of {{convert|740|m}} on the slopes of the Sow of Atholl, but has since been found at a few sites in the Ben Alder forest.<ref name="Coker"/> It became a protected species in the UK in 1975 under the Conservation of Wild Creatures and Wild Plants Act.<ref>{{Cite web|url=http://www.caithness.org/caithnessfieldclub/bulletins/1975/october/conservation.htm|title = Caithness CWS - Caithness Field Club - Annual Bulletins - 1975 - October - Conservation}}</ref> There are reports of the plant's occurrence in the Swiss Alps, but no herbarium specimens have been found to confirm this.<ref name="Coker"/> The species has not been observed on the Faroe Islands, Jan Mayen, Bjørnøya, Svalbard or Franz Josef Land.<ref name="Coker"/>

In Asia, ''Phyllodoce caerulea'' occurs in the Ural Mountains, around Lake Baikal and in the Mongolian Khangai and Kentii mountains, but is absent from most of central Siberia. It occurs on Hokkaido, Sakhalin, the Kamchatka Peninsula and in Beringia.<ref name="Coker"/>

In North America, ''P.&nbsp;caerulea'' is found in coastal Alaska, the Northwest Territories, Quebec and Labrador, as well as scattered sites in the Gaspé Peninsula and the White Mountains of New Hampshire and Vermont.<ref name="Coker"/> It is widespread and common in Greenland.<ref name="Coker"/> Its absence from the Yukon has been described as "surprising".<ref name="Coker"/>

==Taxonomy== ''Phyllodoce caerulea'' was first described by Carl Linnaeus in his 1753 ''{{lang|la|Species Plantarum}}'', as a species in the genus ''Andromeda''. It was transferred to the genus ''Phyllodoce'' by Cardale Babington in his 1843 ''Manual of British Botany''.<ref name="FNA">{{cite book |author1=John G. Packer |author2=A. Joyce Gould |name-list-style=amp |chapter=''Phyllodoce'' Salisbury, Parad. Lond. 1: plate 36. 1806 |title=Magnoliophyta: Paeoniaceae to Ericaceae |series=Flora of North America |volume=8 |publisher=Oxford University Press |isbn=978-0-19-534026-6 |url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=200016320}}</ref> In Japan, ''P.&nbsp;caerulea'' hybridises with the pale yellowish-flowering species ''P.&nbsp;aleutica'' to produce F<sub>1</sub> offspring with flowers that are pink, orange or striped in pink and yellowish white.<ref>{{cite journal |author1=Y. Kameyama, T. Kasagi |author2=G. Kudo |name-list-style=amp |year=2008 |title=A hybrid zone dominated by fertile F<sub>1</sub>s of two alpine shrub species, ''Phyllodoce caerulea'' and ''Phyllodoce aleutica'', along a snowmelt gradient |journal=Journal of Evolutionary Biology |volume=21 |issue=2 |pages=588–597 |doi=10.1111/j.1420-9101.2007.01476.x|pmid=18205785 |doi-access=free }}</ref>

==References== {{Reflist|32em}}

==Further reading== *{{cite journal |author=E. C. Nelson |year=1977 |title=The discovery in 1810 and subsequent history of ''Phyllodoce caerulea'' (L.) Bab. in Scotland |journal=Western Naturalist |volume=6 |pages=45–72}}

==External links== *{{Commons category-inline|Phyllodoce caerulea|''Phyllodoce caerulea''}} *{{Wikispecies-inline|Phyllodoce caerulea|''Phyllodoce caerulea''}}

{{Taxonbar|from=Q478437}}

Category:Flora of the Arctic Category:Ericoideae Category:Flora of Europe Category:Flora of Korea Category:Flora of Northern America Category:Flora of temperate Asia Category:Plants described in 1753 Category:Botanical taxa named by Carl Linnaeus