Editing Thuja plicata (section)

== Description ==
''Thuja plicata'' is a large to very large tree, ranging up to {{convert|45|to|70|m|abbr=off|-1}} tall and {{cvt|2.4|to|7|m|ft|0}} in trunk diameter,<ref name="Arno">{{Cite book |last1=Arno |first1=Stephen F. |url=https://books.google.com/books?id=qDD4DwAAQBAJ |title=Northwest Trees: Identifying & Understanding the Region's Native Trees |last2=Hammerly |first2=Ramona P. |publisher=[[Mountaineers Books]] |year=2020 |isbn=978-1-68051-329-5 |edition=field guide |location=Seattle |pages=155–162 |language=en |oclc=1141235469 |orig-date=1977 |access-date=13 March 2022 |archive-date=19 September 2023 |archive-url=https://web.archive.org/web/20230919000929/https://books.google.com/books?id=qDD4DwAAQBAJ |url-status=live }}</ref><ref name="Gymnosperm">{{Gymnosperm Database|family=Cupressaceae|genus=Thuja|species=plicata}}</ref>{{sfn|Farjon|2005}} larger than any other species in its genus.<ref>{{Gymnosperm Database|family=Cupressaceae|genus=Thuja}}</ref> The trunk swells at the base and has shallow roots.<ref name="Arno" /> The [[Bark (botany)|bark]] is thin, gray-brown, and fissured into vertical bands.<ref name="Arno" /> Trees growing in the open may have a crown that reaches the ground, whereas trees densely spaced together will exhibit a crown only at the top, where light can reach the leaves.{{sfn|Stewart|1984|p=24}} As the tree ages, the top is damaged by wind and replaced by inferior branches.<ref name="Arno" /> The species is long-lived; some trees can live well over a thousand years, with the oldest verified aged 1,460.<ref name="Gymnosperm" />{{sfn|Farjon|2005}}

The foliage forms flat sprays with scale-like leaves in opposite pairs, with successive pairs at 90 degrees to each other. The foliage sprays are green throughout but marked with whitish [[Stoma|stomatal]] bands below; they emit a strong aroma reminiscent of [[pineapple]] when crushed. The individual leaves are {{convert|1|to|4|mm|frac=32}} long and {{cvt|1|to|2|mm|frac=32}} broad on most foliage sprays but up to {{cvt|12|mm|frac=8}} long on strong-growing lead shoots.<ref name="Gymnosperm" />{{sfn|Farjon|2005}} The foliage of individual branchlets turns orange-brown before falling off in autumn.<ref name="Arno" /> Branches growing in full sunlight produce denser foliage with more overlap, while shaded branches grow more horizontally, with less overlap.<ref>{{cite journal |last1 = Edelstein |first1 = Zoe R. |last2 = Ford |first2 = E. David |date = 2 June 2003 |title = Branch and foliage morphological plasticity in old-growth ''Thuja plicata'' |journal = Tree Physiology |publisher = Heron Publishing |publication-place = Victoria, BC |volume = 23 |issue = 10 |pages = 649{{ndash}}662 |doi = 10.1093/treephys/23.10.649 |pmid = 12777238 |doi-access=free}}</ref>

The [[conifer cone|cones]] are slender, {{cvt|10|to|18|mm|frac=16}} long, and {{cvt|4|to|5|mm|frac=32}} broad, with 8 to 12 (rarely 14) thin, overlapping scales. They are green to yellow-green, ripening brown in fall about six months after pollination, and open at maturity to shed the seeds. The seeds are {{cvt|4|to|5|mm|frac=32}} long and {{cvt|1|mm|frac=32}} broad, with a narrow papery wing down each side. The [[pollen]] cones are {{cvt|3|to|4|mm|frac=32}} long, red or purple initially, and shed yellow pollen in spring.<ref name="Gymnosperm" />{{sfn|Farjon|2005}}

<gallery>
File:Thuja bark Łazienki.JPG|[[Bark (botany)|Bark]]|alt=The bark is fibrous and longitudinally fissured.
File:Thuja plicata kz3.JPG|[[Leaves]]|alt=The leaves have white markings on the undersides of the flat foliage sprays.
File:Thuja plicata 21 4 2017 Kaisaniemi 0016 (cropped).jpg|[[Shoot (botany)|Shoot]] with [[pollen cone]]s
File:Thuja plicata 43569.JPG|Shoot with mature [[seed cone]]s
File:Western red cedars, looking up.jpg|[[Keats Island (British Columbia)|Keats Island]]
File:Radial section of a WRC wood specimen (Thuja plicata).jpg|[[Wood]] specimen
</gallery>

=== Chemistry ===
The [[heartwood]] of western redcedar contains numerous chemical substances, such as [[plicatic acid]], [[thujaplicatin methyl ether]], [[hinokitiol]] and other [[thujaplicin]]s, {{nowrap|β-[[thujaplicinol]]}}, [[thujic acid]], [[methyl thujate]], [[1,4-cineole]], and {{nowrap|[[γ-eudesmol]]}}.<ref>{{cite journal |last1=Daniels |first1=C. R. |last2=Russell |first2=J. H. |date=1 May 2007 |title=Analysis of Western Redcedar (''Thuja plicata'' Donn) Heartwood Components by HPLC as a Possible Screening Tool for Trees with Enhanced Natural Durability |journal=[[Journal of Chromatographic Science]]|volume=45 |issue=5 |pages=281–285 |doi=10.1093/chromsci/45.5.281 |pmid=17555638 |doi-access=free}}</ref> Plicatic acid is believed to be the main irritant and [[contact allergen]] responsible for provoking [[allergic reaction]]s and [[asthma]] exacerbation. This leads to [[occupational asthma]] in [[woodworker]]s that are exposed to western redcedar [[wood dust]].<ref>{{cite journal |last1=Chan-Yeung |first1=Moira |date=January 1994 |title=Mechanism of occupational asthma due to western redcedar (''Thuja plicata'') |journal=[[American Journal of Industrial Medicine]]|volume=25 |issue=1 |pages=13–18 |doi=10.1002/ajim.4700250106 |pmid=8116639}}</ref> Thujaplicins serve as natural [[fungicide]]s{{sfn|Gardner|1963|p=21}}{{sfn|Chedgy|Lim|Breuil|2009}} which prevent the wood from [[Wood-decay fungus|rotting]]. This effect lasts around a century even after the tree is felled. However, thujaplicins are only found in older trees. Saplings do not produce the chemical, causing them to often develop rot at an early stage, causing some trees to grow with a somewhat hollow trunk, as the tree moves to heal itself as it grows.{{sfn|Stewart|1984|p=22}} Due to their fungicidal and anti-[[Food browning|browning]] properties, thujaplicins are used in agriculture for fungal diseases and to prevent [[Post-harvest losses (vegetables)|post-harvest decay]].<ref>{{cite journal |last1=Morita |first1=Yasuhiro |last2=Matsumura |first2=Eiko |last3=Okabe |first3=Toshihiro |last4=Fukui |first4=Toru |last5=Shibata |first5=Mitsunobu |last6=Sugiura |first6=Masaaki |last7=Ohe |first7=Tatsuhiko |last8=Tsujibo |first8=Hiroshi |last9=Ishida |first9=Nakao |last10=Inamori |first10=Yoshihiko |date=2004 |title=Biological Activity of α-Thujaplicin, the Isomer of Hinokitiol |journal=[[Biological & Pharmaceutical Bulletin]]|volume=27 |issue=6 |pages=899–902 |doi=10.1248/bpb.27.899 |pmid=15187442 |doi-access=free}}</ref><ref>{{cite journal |last1=Vanitha |first1=Thiraviam |last2=Thammawong |first2=Manasikan |last3=Umehara |first3=Hitomi |last4=Nakamura |first4=Nobutaka |last5=Shiina |first5=Takeo |date=December 2019 |title=Effect of hinokitiol impregnated sheets on shelf life and quality of "KEK-1" tomatoes during storage |journal=[[Packaging Technology and Science]]|volume=32 |issue=12 |pages=641–648 |doi=10.1002/pts.2479 |s2cid=202995336}}</ref> Thujaplicins, like other tropolones, are potent chelating agents and bind divalent metal ions.<ref>{{cite journal |last1=Pietra |first1=Francesco |date=August 1973 |title=Seven-membered conjugated carbo- and heterocyclic compounds and their homoconjugated analogs and metal complexes. Synthesis, biosynthesis, structure, and reactivity |journal=[[Chemical Reviews]]|volume=73 |issue=4 |pages=293–364 |doi=10.1021/cr60284a002}}</ref> [[Basic research|Basic]] and [[animal studies]] have shown that thujaplicins may have other biological properties, including antibacterial, antiviral, and antioxidant activities,<ref>{{cite journal |last1=Saniewski |first1=Marian |last2=Horbowicz |first2=Marcin |last3=Kanlayanarat |first3=Sirichai |date=10 September 2014 |title=The Biological Activities of Troponoids and Their Use in Agriculture A Review |journal=[[Journal of Horticultural Research]]|volume=22 |issue=1 |pages=5–19 |doi=10.2478/johr-2014-0001 |doi-access=free |s2cid=33834249}}</ref> however reliable evidence on their effectiveness is still lacking.{{Cn|date=May 2025}}