{{Short description|Species of plant in the mint family}} {{Speciesbox | image = Glechoma hederacea - Keila.jpg | genus = Glechoma | species = hederacea | authority = L. | synonyms_ref = <ref name="POWO">{{cite POWO |id=447338-1 |title=''Glechoma hederacea'' L. |access-date=20 November 2024}}</ref> | synonyms = {{Collapsible list | {{Species list | Calamintha hederacea | (L.) Scop. | Chamaecissos hederaceus | (L.) Nieuwl. & Lunell | Chamaeclema hederacea | (L.) Moench | Glechoma borealis | Salisb. | Glechonion hederaceum | (L.) St.-Lag. | Nepeta glechoma | Benth. | Nepeta hederacea | (L.) Trevis. }} }} }}
[[File:Ground Ivy (Glechoma hederacea) Spectral comparison Vis UV IR.jpg|thumbnail|right|Flower's appearance in visible, UVA, and NIR spectrums. The UV nectar guides may help attract bees.]] thumb|
'''''Glechoma hederacea''''' is an aromatic, perennial, evergreen creeper of the mint family Lamiaceae. It is commonly known as '''ground-ivy''', '''gill-over-the-ground''',<ref name="caes">''[https://web.archive.org/web/20091106073858/http://ct.gov/caes/lib/caes/invasive_aquatic_plant_program/pdf_reports/invplantsct05.pdf Connecticut Invasive Plant List]'', Connecticut Agricultural Experiment Station, January, 2004</ref> '''creeping charlie''', '''alehoof''', '''tunhoof''', '''catsfoot''', '''field balm''', and '''run-away-robin'''.<ref name="caes"/> It is also sometimes known as '''creeping jenny''', but that name more commonly refers to ''Lysimachia nummularia''. It is used as a salad green in many countries.
European settlers carried it around the world, and it has become a well-established introduced and naturalized plant in a wide variety of localities. It is also considered an aggressive invasive weed of woodlands and lawns in some parts of North America. In the absence of any biological control research conducted by the USDA,<ref name="waggy">{{cite web |url=https://www.fs.fed.us/database/feis/plants/forb/glehed/all.html |title=Glechoma hederacea |last=Waggy |first=Melissa |date=2009 |website=USDA FEIS |publisher=United States government |access-date=19 March 2018}}</ref> herbicides are relied upon (despite their drawbacks) particularly for woodland ecosystems. The plant's extensive root system makes it difficult to eradicate by hand-pulling.
==Description== ''Glechoma hederacea'' can be identified by its round to reniform (kidney- or fan-shaped), crenate (with round-toothed edges) opposed leaves {{convert|2–3|cm|abbr=on|frac=4}} diameter, on {{convert|3–6|cm|abbr=on|frac=4}} long petioles attached to square stems that root at the nodes. The plant spreads either by stolon or seed, making it exceptionally difficult to eradicate. It is a variable species, its size being influenced by environmental conditions, from {{convert|5–50|cm|abbr=on|frac=2}} tall.<ref name="Hutchings & Price">{{cite journal|last1=Hutchings|first1=Michael J.|last2=Price|first2=Elizabeth C.|title=Glechoma hederecea|journal=Journal of Ecology|date=1999|volume=87|issue=205|pages=347–364|doi=10.1046/j.1365-2745.1999.00358.x|s2cid=85065999 }}</ref>
The flowers of ''G. hederacea'' are bilaterally symmetrical, funnel shaped, blue or bluish-violet to lavender, and grow in opposed clusters of two or three flowers in the leaf axils on the upper part of the stem or near the tip. It usually flowers in the spring.
=== Reproduction === ''Glechoma hederecea'' is gynodioecious, with genets being either female or hermaphrodite. The females depend upon pollen from hermaphrodites for pollination.<ref name="Hutchings & Price" /> Female flowers tend to be smaller than hermaphrodite flowers.<ref name="Hutchings & Price" /> Disagreement exists among biologists as to whether hermaphrodite flowers can pollinate themselves.<ref name="Hutchings & Price" /> The plant spends the winter as either a small ramet or a small rosette. It produces flowers between April and July, which are visited by many types of insects, and can be characterized by a generalized pollination syndrome.<ref>{{Cite journal |last1=Van Der Kooi |first1=C. J. |last2=Pen |first2=I. |last3=Staal |first3=M. |last4=Stavenga |first4=D. G. |last5=Elzenga |first5=J. T. M. |year=2015 |title=Competition for pollinators and intra-communal spectral dissimilarity of flowers |url=https://www.researchgate.net/publication/273158762 |journal=Plant Biology |volume=18 |issue=1 |pages=56–62 |doi=10.1111/plb.12328 |pmid=25754608|hdl=11370/caee8d0d-9724-4056-9d45-93162a5a7afc |hdl-access=free }}</ref> Each pollinated flower can produce up to four seeds, which are dispersed by the stem bending over and depositing the ripe seeds in the ground adjacent to the parent plant, although ants may carry the seeds further. The seeds germinate a few days after contact with moisture, although they can be stored dry.<ref name="Hutchings & Price" /> Dry storage for a period up to a month is thought to improve the germination rate.<ref name="Hutchings & Price" />
The plant can also reproduce clonally, with the stems bending down to the earth and allowing roots to attach themselves.<ref name="Hutchings & Price" /> Single clones can grow several metres across, although precise data are not available.<ref name="Hutchings & Price" />
=== Similar species === ''G. hederacea'' is sometimes confused with common mallow (''Malva neglecta''), which also has round, lobed leaves, but mallow leaves are attached to the stem at the back of a rounded leaf, where ground ivy has square stems and leaves, which are attached in the center of the leaf, more prominent rounded lobes on their edges, attach to the stems in an opposite arrangement, and have a hairy upper surface. In addition, mallow and other creeping plants sometimes confused with ground ivy do not spread from nodes on stems. In addition, ground ivy emits a distinctive odor when damaged, being a member of the mint family.
== Distribution and habitat == European settlers carried it around the world, and it has become a well-established introduced and naturalized plant in a wide variety of localities. It is also considered an aggressive invasive weed of woodlands and lawns in some parts of North America, being considered a non-native plant in the United States, and invasive in some U.S. states.<ref>[https://plants.usda.gov/home/plantProfile?symbol=GLHE2 U.S. Department of Agriculture Natural Resources Conservation Services]</ref> It has invaded wild areas, sometimes choking out native wildflowers.
''G. hederacea'' thrives in moist shaded areas, but also tolerates sun very well. It is a common plant in grasslands and wooded areas or wasteland. It also thrives in lawns and around buildings, since it survives mowing. Part of the reason for its wide distribution is its rhizomatous method of reproduction.
==Ecology== A number of wild bees collect pollen from this plant, including ''Anthophora furcata'', ''Anthidum manicatum'', ''Anthophora plumipes'', ''Anthophora quadrimaculata'', ''Osmia aurulenta'', ''Osmia caerulentes'', and ''Osmia uncinata''. The plant is also galled by several insects,<ref>{{Cite web |url=http://www.bugsandweeds.co.uk/galls%20p2.html#GrndIvy2 |title="A Nature Observer′s Scrapbook" galls found on herbaceous, soft stemmed plants |access-date=2010-06-06 |archive-date=2020-02-16 |archive-url=https://web.archive.org/web/20200216133802/http://www.bugsandweeds.co.uk/galls%20p2.html#GrndIvy2 |url-status=dead }}</ref> including ''Rondaniola bursaria'' (lighthouse gall),<ref>[http://www.bioimages.org.uk/html/t44316.htm] {{webarchive|url=https://web.archive.org/web/20080708221614/http://www.bioimages.org.uk/html/t44316.htm|date=July 8, 2008}}</ref> ''Liposthenes glechomae''<ref>[http://www.bladmineerders.nl/gallen/liposthenes/glechomae/glechomae.htm Leafminers of Europe - Liposthenes glechomae] {{webarchive|url=https://web.archive.org/web/20070908115739/http://www.bladmineerders.nl/gallen/liposthenes/glechomae/glechomae.htm |date=2007-09-08 }}</ref> or ''Liposthenes latreillei'' (Kieffer, 1898) (a gall wasp).<ref>[http://www.bioimages.org.uk/html/t38646.htm] {{webarchive|url=https://web.archive.org/web/20080720030546/http://www.bioimages.org.uk/html/t38646.htm|date=July 20, 2008}}</ref>
It forms dense mats that can take over areas of lawn and woodlands, thus is considered an invasive or aggressive weed in suitable climates where it is not native.<ref name="caes" />
=== Control === A non-native invasive in North America, ''Glechoma'' is familiar to a large number of people as a weed, a property it shares with many others of the mint family. It can be a problem in heavy, rich soils with good fertility, high moisture, and low boron content. It thrives particularly well in shady areas where grass does not grow well, such as woodlands, although it can also be a problem in full sun.
Because the plant is stoloniferous and continues to spread from its roots or bits of stem which reroot, even small infestations resist repeated hand weeding. Like crabgrass, ''G. hederacea''<nowiki/>'s root has a tough-to-remove ball (unbelied by its delicate wide leaves).
No biological control agents are known to help to reduce its spread in North America.<ref name="waggy" /> Commercial herbicides containing triclopyr are used to control the plant.
''G. hederacea'' is also unusually sensitive to boron, and can be killed by applying borax (sodium tetraborate) in solution. However, borax is toxic to ants and to animals at only slightly higher concentrations, and does not break down in the environment. In addition to adverse long-term effects on soil or groundwater,<ref>[http://www.extension.umn.edu/info-u/plants/BG522.html Creeping Charlie Control - Borax] {{webarchive|url=https://web.archive.org/web/20060822172632/http://www.extension.umn.edu/info-u/plants/BG522.html|date=2006-08-22}} University of Minnesota Info-U</ref><ref>[http://www.ipm.iastate.edu/ipm/hortnews/1997/8-22-1997/borax.html Borax on Ground Ivy: Boon or Bane?] Horticulture and Home Pest News, Iowa State University</ref> recent research discounts the very efficacy of borax treatment, primarily because finding the correct concentration for a given area is difficult and the potential for damaging desired plants is high.<ref>{{cite web |title=Controlling Creeping Charlie |url=http://www.hort.wisc.edu/mastergardener/Features/weeds/creepingcharlie/creepcharlie.htm |url-status=dead |archive-url=https://web.archive.org/web/20080608231426/http://www.hort.wisc.edu/mastergardener/Features/weeds/creepingcharlie/creepcharlie.htm |archive-date=2008-06-08 |access-date=2008-06-01}} University of Wisconsin</ref>
== Safety == Although it has been used by humans as a salad green and in herbal medicines for thousands of years, the species is also believed to be toxic to livestock, particularly horses. Wild pigs, however, are reported to feed on it. Some accounts report it is toxic to rodents, while bank voles in Great Britain have been observed to use it as a food source.<ref name="waggy" /> Like other members of the Lamiaceae, ''G. hederacea'' contains bioactive volatile oils, including terpenoids and pulegone; these are responsible for the characteristic "minty" odor and taste of plants in the mint family. Their activity in humans varies depending on many factors, including concentration, quantity of intake, and whether administration is internal or external. Lamiacaeae plants with very high volatile oil concentrations, such as European pennyroyal (''Mentha pulegium''), have traditional uses as disinfectants, flea-killers, and abortifacients, and are hepatotoxic to humans.<ref>{{Cite web |title=Pennyroyal Uses, Benefits & Side Effects - Drugs.com Herbal Database |url=https://www.drugs.com/npc/pennyroyal.html |access-date=2020-04-25 |website=Drugs.com |language=en}}</ref> Other members of the Lamiacaeae, such as ''Mentha spicata'', spearmint, are widely and safely used in teas and flavorings for their volatile oils. The concentration of volatile oil in ''G. hederacea'' is less than 1/30th that in European pennyroyal.<ref name="barnes">Joanne Barnes, Linda A. Anderson, J. David Phillipson, ''Herbal Medicines'', 2nd ed., Pharmaceutical Press, London, 2002.</ref> The effects of ''Glechoma'' on humans have been little studied.
== Uses == right|thumb|Botanical illustration It is grown as a garden plant in pots and occasionally as a groundcover. Easily cultivated, it grows well in shaded places. A variegated variety is commercially available; in many areas, this is the dominant form, which has escaped cultivation and become established as an aggressive, adventitious groundcover.
The pre-bloom leaves can be cooked as a vegetable or made into tea.<ref name="tfb">{{Cite book |last=Francis-Baker |first=Tiffany |title=Concise Foraging Guide |date=2021 |publisher=Bloomsbury |isbn=978-1-4729-8474-6 |series=The Wildlife Trusts |location=London |pages=85}}</ref>
''G. hederacea'' was also widely used by the Saxons in brewing ale as flavoring, clarification, and preservative, and later by the English, before the introduction of hops into brewing in the late 15th century. From this, the brewing-related names arose for the herb, e.g. alehoof, tunhoof, and gill-over-the-ground.<ref name=Grieve>{{cite web |url=https://botanical.com/botanical/mgmh/i/ivygro16.html |author=Grieve, Maud|author-link=Maud Grieve |title=''A Modern Herbal'' (botanical.com)|accessdate=2025-05-25}}</ref> In the 18th century, beer brewed with ground ivy was known as ''gill ale'' and was said to have medicinal properties.<ref>{{cite book |title=A Curious Herbal |url=https://archive.org/details/2449056RX1.nlm.nih.gov/page/n3/mode/2up |author=Blackwell, Elizabeth|author-link=Elizabeth Blackwell (illustrator) |year=1737 |page=[https://archive.org/details/2449056RX1.nlm.nih.gov/page/n571/mode/2up?view=theater 57]|publisher=London: Samuel Harding}}</ref> It was made by infusing the herb in strong ale and was sold at coffee and victualling houses.<ref>{{Cite book |last1=Broadbent |first1=Humphrey |date=1722 |title=The Domestick Coffee-man, Shewing the True Way of Preparing and Making of Chocolate, Coffee and Tea |url=https://www.google.de/books/edition/The_Domestick_Coffee_Man_Shewing_the_Tru/6WRpAAAAcAAJ?hl=de&gbpv=0 |language=en |location=London |publisher=E. Curll and T. Bickerton |page=17 |oclc=719428100 |url-status=live |archive-url=https://web.archive.org/web/20250525000000/https://www.google.de/books/edition/The_Domestick_Coffee_Man_Shewing_the_Tru/6WRpAAAAcAAJ?hl=de&gbpv=0 |archive-date=25 May 2025 |access-date=25 May 2025}} [https://archive.org/details/the-domestick-coffee-man-shewing-the-tru Alt URL]</ref>
Enzymes similar to chymosin in ''G. hederacea'' have been used in the cheese-making process as a substitute for animal rennet.<ref>[https://web.archive.org/web/20160317223337/http://www.cheesemakingrecipe.com/Rennet.html Cheesemakingrecipe.com: Rennet for Cheese Making]</ref><ref>[https://web.archive.org/web/20240119155337/http://web.archive.org/screenshot/https://thecheesewanker.com/science/plant-based-rennet/ TheCheesewanker.com: Science, Plant based rennet]</ref>
[[Image:Warming-Skudbygning-Fig9-Glechoma-hederacea.jpg|thumb|right|''G. hederacea'' seedling - ''cot'' = cotyledons; ''ga'' = axillary bud, from (Warming 1884)]]
===Traditional medicine=== ''G. hederacea'' has been used in the traditional medicine of Europe going back thousands of years; Galen recommends the plant to treat inflammation of the eyes. John Gerard, an English herbalist, recommended it to treat tinnitus, and as a "diuretic, astringent, tonic, and gentle stimulant. Useful in kidney diseases and for indigestion." It has also been used as a "lung herb". Its presence as an invasive weed in North America is the result of the value placed on it by European settlers as a medicinal herb and ale preservative; the species was imported and widely cultivated in herb and kitchen gardens.<ref>Stubbendieck, James; Coffin, Mitchell J.; Landholt, L. M. 2003. Weeds of the Great Plains. 3rd ed. Lincoln, NE: Nebraska Department of Agriculture, Bureau of Plant Industry. 605 p. In cooperation with: University of Nebraska, Lincoln.</ref> Its other traditional uses include as an expectorant or astringent, and to treat bronchitis.<ref name="barnes" /> In traditional Austrian medicine, the herb has been prescribed for internal application as salad or tea for the treatment of a variety of different conditions, including disorders associated with the liver and bile, gastrointestinal tract, respiratory tract, kidneys and urinary tract, fever, and influenza.<ref>{{cite journal | last1 = Vogl | first1 = S | last2 = Picker | first2 = P | last3 = Mihaly-Bison | first3 = J | last4 = Fakhrudin | first4 = N | last5 = Atanasov | first5 = AG | last6 = Heiss | first6 = EH | last7 = Wawrosch | first7 = C | last8 = Reznicek | first8 = G | last9 = Dirsch | first9 = VM | last10 = Saukel | first10 = J | last11 = Kopp | first11 = B | year = 2013 | title = Ethnopharmacological in vitro studies on Austria's folk medicine - An unexplored lore in vitro anti-inflammatory activities of 71 Austrian traditional herbal drugs | journal = J Ethnopharmacol | volume = 149| issue = 3| pages = 750–71| doi = 10.1016/j.jep.2013.06.007 | pmid = 23770053 | pmc=3791396}}</ref> In traditional Chinese medicine, it is known as Jiangsu Jinqiancao.
==References== {{Reflist|2}}
==Further reading== * {{cite journal | last1 = An | first1 = HJ | last2 = Jeong | first2 = HJ | last3 = Um | first3 = JY | last4 = Kim | first4 = HM | last5 = Hong | first5 = SH | year = 2006 | title = Glechoma hederacea inhibits inflammatory mediator release in IFN-gamma and LPS-stimulated mouse peritoneal macrophages | journal = Journal of Ethnopharmacology | volume = 106 | issue = 3| pages = 418–24 | doi=10.1016/j.jep.2006.01.024 | pmid=16530364}}
==External links== {{Commons}} *[https://web.archive.org/web/19980115061259/http://www.ppws.vt.edu/scott/weed_id/glehe.htm Ground Ivy: ''Glechoma hederacea''] *[http://www.ext.nodak.edu/extnews/hortiscope/weed/grndivy.htm Questions on: Ground Ivy] *[https://web.archive.org/web/20080214044431/http://www.agry.purdue.edu/turf/tips/2004/ivy910.htm Attempting Ground Ivy Control] *''[https://pfaf.org/user/Plant.aspx?LatinName=Glechoma+hederacea Glechoma hederacea]'' *[https://web.archive.org/web/20060511154244/http://www.extension.umn.edu/yardandgarden/ygbriefs/h519borax.html Using Borax to Control Creeping Charlie]
{{Taxonbar|from=Q162544}}
Category:Lamiaceae Category:Medicinal plants of Asia Category:Medicinal plants of Europe Category:Edible plants Category:Flora of Europe Category:Flora of Asia Category:Plants described in 1753 Category:Botanical taxa named by Carl Linnaeus