{{short description|Plant that has leaves in all seasons}} {{About|the type of plant}} [[File:Abies alba 02.jpg|right|300px|thumb|A silver fir shoot showing three successive years of retained leaves]] [[File:Εθνικός Δρυμός Σαμαριάς.jpg|thumb|304x304px|''Cupressus sempervirens'' (Mediterranean cypress), an evergreen tree]] In botany, an '''evergreen''' is a plant which has foliage that remains green and functional throughout the year.<ref>{{Cite web |date=2023-01-23 |title=Evergreen |url=https://mgnv.org/plants/glossary/evergreen/ |access-date=2024-06-07 |website=Master Gardeners of Northern Virginia |language=en-US}}</ref> This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many different species, the unique feature of evergreen plants lends itself to various environments and purposes.
==Evergreen species== {{cite section|date=December 2022}} There are many different kinds of evergreen plants, including trees, shrubs, and vines.<ref>{{cite encyclopedia |title=Evergreen |encyclopedia=Encyclopaedia Britannica |url=https://www.britannica.com/science/evergreen |access-date=2025-12-05}}</ref> Evergreens include: * Most species of conifers (e.g., pine, hemlock, spruce, and fir), but not all (e.g., larch).<ref>{{Cite web |last=Rose |first=Nancy |date=2016-01-06 |title=Not All Conifers are Evergreen |url=https://arboretum.harvard.edu/stories/not-all-conifers-are-evergreen/ |access-date=2024-06-07 |website=Arnold Arboretum |publisher=Harvard University |language=en-us}}</ref> * Live oak, holly, and "ancient" gymnosperms such as cycads * Many woody plants from frost-free climates * Rainforest trees * All eucalypts * Clubmosses and relatives * Most bamboos
The Latin binomial term {{Wikt-lang|la|sempervirens}}, meaning "always green", refers to the evergreen nature of the plant, for instance: :''Cupressus sempervirens'' (a cypress) :''Lonicera sempervirens'' (a honeysuckle) :''Sequoia sempervirens'' (a sequoia)
The longevity of individual leaves in evergreen plants varies from a few months to several decades, up to a maximum of 45 years in the Great Basin bristlecone pine ''Pinus longaeva''.<ref>{{Cite journal|doi=10.1007/BF00344660|pmid=28310317|last1=Ewers|first1=F. W.|last2=Schmid|first2=R.|year=1981|title=Longevity of needle fascicles of ''Pinus longaeva'' (bristlecone pine) and other North American pines|journal=Oecologia|volume=51|issue=1|pages=107–15|bibcode=1981Oecol..51..107E|s2cid=19465953 | url=http://link.springer.com/10.1007/BF00344660 | access-date=2025-06-28|url-access=subscription}}</ref>
=== Prominent families including evergreen species === {| class="wikitable" |- ! Family name !! Example |- | Cyatheaceae || Australian tree fern |- | Cycadaceae || Queen sago |- | Araucariaceae || Kauri |- | Podocarpaceae || Real yellowwood |- | Taxaceae || Yew |- | Cupressaceae || Sequoia |- | Pinaceae || Pine |- | Aquifoliaceae || Holly |- | Fagaceae || Live oak |- | Rosaceae || Loquat |- | Fabaceae || Wattle |- | Rutaceae || Citrus |- | Apocynaceae || Oleander |- | Ericaceae || Rhododendron |- | Oleaceae || Olive |- | Myrtaceae || Eucalyptus |- | Arecaceae || Coconut |- | Lauraceae || Bay |- | Magnoliaceae || Southern magnolia |}
== Differences between evergreen and deciduous species == Evergreen and deciduous species vary in a range of morphological and physiological characters. Generally, broad-leaved evergreen species have thicker leaves than deciduous species, with a larger volume of parenchyma and air spaces per unit leaf area.<ref>{{Cite journal |last1=Villar |first1=Rafael |last2=Ruiz-Robleto |first2=Jeannete |last3=Ubera |first3=José Luis |last4=Poorter |first4=Hendrik |date=October 2013 |title=Exploring variation in leaf mass per area (LMA) from leaf to cell: An anatomical analysis of 26 woody species |journal=American Journal of Botany |volume=100 |issue=10 |pages=1969–1980 |doi=10.3732/ajb.1200562 |pmid=24107583}}</ref> They have larger leaf biomass per unit leaf area, and hence a lower specific leaf area. Construction costs do not differ between the groups.{{citation needed|date=February 2023}} Evergreens have generally a larger fraction of total plant biomass present as leaves (LMF),<ref>{{Cite journal |last1=Poorter |first1=Hendrik |last2=Jagodzinski |first2=Andrzej M. |last3=Ruiz-Peinado |first3=Ricardo |last4=Kuyah |first4=Shem |last5=Luo |first5=Yunjian |last6=Oleksyn |first6=Jacek |last7=Usoltsev |first7=Vladimir A. |last8=Buckley |first8=Thomas N. |last9=Reich |first9=Peter B. |last10=Sack |first10=Lawren |date=2015 |title=How does biomass distribution change with size and differ among species? An analysis for 1200 plant species from five continents |journal=New Phytologist |volume=208 |issue=3 |pages=736–749 |bibcode=2015NewPh.208..736P |doi=10.1111/nph.13571 |pmc=5034769 |pmid=26197869}}</ref> but they often have a lower rate of photosynthesis.
==Reasons for being evergreen or deciduous== {{Refimprovesect|date=August 2023}} [[Image:Live oak Georgetown.jpg|right|thumb|A southern live oak in South Carolina during winter]] [[File:Ecuadorian Amazon rain forest, looking toward the Andes.jpg|thumb|Ecuadorian Amazon rainforest. This humid tropical forest has warm temperatures and receives rainfall year round. Vegetation consists of a majority of broadleaf evergreen species.<ref>{{Cite web |last=Woodward |first=Dr. Susan L. |title=Amazon Rainforest |url=https://php.radford.edu/~swoodwar/biomes/?page_id=2052 |access-date=2024-11-16 |website=Department of Geospatial Science, Radford University|archive-url=https://web.archive.org/web/20241211222028/https://php.radford.edu/~swoodwar/biomes/?page_id=2052|archive-date=2024-12-11}}</ref>]]
Deciduous trees shed their leaves usually as an adaptation to a cold or dry/wet season. Evergreen trees also lose leaves, but each tree loses its leaves gradually and not all at once. Most tropical rainforest plants are considered to be evergreens, replacing their leaves gradually throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous. Most warm temperate climate plants are also evergreen.{{Citation needed|date=February 2023}} In cool temperate climates, fewer plants are evergreen. In such climates, there is a predominance of conifers because few evergreen broadleaf plants can tolerate severe cold below about {{convert|-26|C|F}}.{{Clarify|reason=check stated temperature|date=February 2023}}{{Citation needed|date=February 2023}} In addition, evergreen foliage experiences significant leaf damage in these cold, dry climates. Root systems are the most vulnerable aspect of many plants. Even though roots are insulated by soil, which tends to be warmer than average air temperatures, soil temperatures that drop too low can kill the plant. The exact temperature which evergreen roots can handle depends on the species, for example, ''Picea glauca'' (White Spruce) roots are killed at {{cvt|-10|F}}.<ref name="Niemiera-2023">{{Cite book |last=Niemiera |first=Alex X. |url=https://pressbooks.lib.vt.edu/emgtraining/chapter/13/ |title=Virginia Cooperative Extension Gardener Handbook |date=2023-03-13 |language=en |chapter=Chapter 13: Woody Landscape Plants}}</ref>
In areas where there is a reason for being deciduous, e.g. a cold season or dry season, evergreen plants are usually an adaptation of low nutrient levels. Additionally, they usually have hard leaves and have an excellent water economy due to scarce resources in the area in which they reside.<ref name="Álvarez-Yépiz-2017">{{Cite journal |last1=Álvarez-Yépiz |first1=Juan C. |last2=Búrquez |first2=Alberto |last3=Martínez-Yrízar |first3=Angelina |last4=Teece |first4=Mark |last5=Yépez |first5=Enrico A. |last6=Dovciak |first6=Martin |date=2017-02-01 |title=Resource partitioning by evergreen and deciduous species in a tropical dry forest |journal=Oecologia |language=en |volume=183 |issue=2 |pages=607–618 |bibcode=2017Oecol.183..607A |doi=10.1007/s00442-016-3790-3 |issn=1432-1939 |pmid=27915413 |s2cid=3798020 }}</ref> The excellent water economy within the evergreen species is due to high abundance when compared to deciduous species,<ref name="Álvarez-Yépiz-2017" /> whereas deciduous trees lose nutrients whenever they lose their leaves. In warmer areas, species such as some pines and cypresses grow on poor soils and disturbed ground.{{Fact|date=August 2023}} In ''Rhododendron'', a genus with many broadleaf evergreens, species were recorded on acidic soils in a temperate Himalayan forest, with soil pH and associated nutrient availability influencing their growth patterns.<ref>{{cite journal |last1=Bharali |first1=Sanjeeb |last2=Paul |first2=Ashish |last3=Khan |first3=Mohamed Latif |title=Soil nutrient status and its impact on the growth of three Rhododendron species in a temperate forest of the eastern Himalayas, India |journal=Taiwan Journal of Forest Science |date=2014-03-01 |volume=29 |issue=1 |pages=33–51 |url=https://www.researchgate.net/profile/Sanjeeb-Bharali-2/publication/261241963_Soil_Nutrient_Status_and_Its_Impact_on_the_Growth_of_Three_Rhododendron_Species_in_a_Temperate_Forest_of_the_Eastern_Himalayas_India/links/00b49533a9dc6943f2000000/Soil-Nutrient-Status-and-Its-Impact-on-the-Growth-of-Three-Rhododendron-Species-in-a-Temperate-Forest-of-the-Eastern-Himalayas-India.pdf |language=en }}</ref> In taiga or boreal forests, it is too cold for the organic matter in the soil to decay rapidly,<ref>{{cite journal | last1 = Boberg | first1 = J. B. | last2 = Finlay | first2 = R. D. | last3 = Stenlid | first3 = J. | last4 = Ekblad | first4 = A. | last5 = Lindahl | first5 = B. D. | title = Nitrogen and Carbon Reallocation in Fungal Mycelia during Decomposition of Boreal Forest Litter | journal = PLOS ONE | year = 2014 | volume = 9 | issue = 3 | article-number = e92897 | doi = 10.1371/journal.pone.0092897 | doi-access = free | pmid = 24651625 | bibcode = 2014PLoSO...992897B | pmc = 3961408 }}</ref> so the nutrients in the soil are less easily available to plants, thus favoring evergreens.<ref name="advantages"/> [[File:Salvia rosmarinus (55026834324).jpg|thumb|A rosemary plant during winter near Frederikshavn, Denmark]] In temperate climates, evergreens can reinforce their own survival; evergreen leaf and needle litter has a higher carbon–nitrogen ratio than deciduous leaf litter, contributing to a higher soil acidity and lower soil nitrogen content. This is the case with Mediterranean evergreen seedlings, which have unique C and N storages that allow stored resources to determine fast growth within the species, limiting competition and bolstering survival.<ref>{{Cite journal |last1=Uscola |first1=Mercedes |last2=Villar-Salvador |first2=Pedro |last3=Gross |first3=Patrick |last4=Maillard |first4=Pascale |date=2015-05-01 |title=Fast growth involves high dependence on stored resources in seedlings of Mediterranean evergreen trees |journal=Annals of Botany |language=en |volume=115 |issue=6 |pages=1001–1013 |doi=10.1093/aob/mcv019 |issn=0305-7364 |pmc=4407060 |pmid=25817313 |doi-access=free}}</ref> These conditions favor the growth of more evergreens and make it more difficult for deciduous plants to persist. In addition, the shelter provided by existing evergreen plants can make it easier for younger evergreen plants to survive cold and/or drought.<ref name="advantages">Aerts, R. (1995). [http://www.falw.vu.nl/nl/Images/Aerts1995_tcm19-94783.pdf "The advantages of being evergreen"]; {{Webarchive|url=https://web.archive.org/web/20150924010354/http://www.falw.vu.nl/nl/Images/Aerts1995_tcm19-94783.pdf |date=2015-09-24 }}. ''Trends in Ecology & Evolution'' 10 (10): 402–407.</ref><ref>{{Cite journal |last=Matyssek |first=R. |date=1986-12-01 |title=Carbon, water and nitrogen relations in evergreen and deciduous conifers |url=https://academic.oup.com/treephys/article-lookup/doi/10.1093/treephys/2.1-2-3.177 |journal=Tree Physiology |language=en |volume=2 |issue=1–2–3 |pages=177–187 |doi=10.1093/treephys/2.1-2-3.177 |pmid=14975852 |issn=0829-318X|url-access=subscription }}</ref><ref>{{Cite journal |last=Sobrado |first=M. A. |date=1991 |title=Cost-Benefit Relationships in Deciduous and Evergreen Leaves of Tropical Dry Forest Species |url=https://www.researchgate.net/publication/271760652 |journal=Functional Ecology |volume=5 |issue=5 |pages=608–616 |doi=10.2307/2389479 |jstor=2389479 |bibcode=1991FuEco...5..608S }}</ref>
== Uses == Evergreen plants can have decorative as well as functional uses. In months where most other plants are dormant, evergreens with their sturdy structure, and vibrant foliage are popular choices to beautify a landscape. Additionally, evergreens can serve as a windbreak, stopping heat loss from buildings during cold months when placed on the (latitude/hemisphere specific) side of a structure. e.g. the northwest in Virginia, USA.<ref name="Niemiera-2023" />
=== Cultural uses === Evergreens have long held cultural significance across many societies; they are commonly used as symbols of life, endurance, and renewal, because they remain green through winter.<ref>{{cite conference |last=Schroeder |first=Herbert W. |year=1992 |title=The tree of peace: Symbolic and spiritual values of the white pine |editor=R. A. Stine |conference=White Pine Symposium Proceedings |pages=73–83 |publisher=U.S. Forest Service, Northern Research Station |location=Duluth, Minnesota |url=https://www.nrs.fs.usda.gov/pubs/jrnl/1992/nc_1992_schroeder_002.pdf }}</ref>
=== Nutritional and medicinal uses === Conifer needle teas have been widely used as a source of vitamin C, helping to prevent or treat scurvy, and as remedies for colds, coughs, and fatigue. Many evergreen teas were valued for antimicrobial, anti-inflammatory, or expectorant properties, attributed to terpenes and phenols found in needles and leaves.<ref>{{cite journal |last1=Popescu |first1=Diana I. |last2=Frum |first2=Adina |last3=Dobrea |first3=Carmen M. |title=Comparative antioxidant and antimicrobial activities of several conifer needles and bark extracts |journal=Pharmaceutics |volume=16 |issue=1 |page=52 |year=2023 |doi=10.3390/pharmaceutics16010052 |doi-access=free |pmid=38258063 |pmc=10821083 }}</ref>
=== Culinary uses === Today, evergreen teas are sometimes consumed for their distinct resinous, forest-like, and citrus-resin notes, and are used in craft beers and craft sodas, herbal infusions, and foraging-based cuisine.<ref>{{cite journal |title=Research into quality of beer with the addition of pine needles extract |journal=Eastern European Journal of Enterprise Technologies |volume=4 |issue=7 |year=2020 |pages= |url=https://www.researchgate.net/publication/316941581 |access-date=2025-12-28 }}</ref>
==See also== {{portal|Plants|Trees|Botany }} * Semi-deciduous (semi-evergreen)
==References== {{reflist}}
==External links== * {{Cite Americana|wstitle=Evergreens|author=Helen Ingersoll |short=x}}
Category:Plants Category:Botany Category:Trees