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Chamaerops

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Chamaerops
Chamaerops humilisvar.humilis,Zingaro,Sicily
Large monospecific patch ofC. humilisin southwestSpain.
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Arecales
Family: Arecaceae
Subfamily: Coryphoideae
Tribe: Trachycarpeae
Genus: Chamaerops
L.
Species:
C. humilis
Binomial name
Chamaerops humilis
L.
Distribution map
Synonyms

Several, including:

  • Chamaerops elegansHook. f.[2]
Transactions of the Linnean Society of London, vol. 10: t. 8 (1815)

Chamaeropsis agenusofflowering plantsin the familyArecaceae.It contains only one species,Chamaerops humilis,variously calledEuropean fan palmor theMediterranean dwarf palm.It is one of the mostcold-hardy palmsand is used in landscaping in temperate climates.[3][4]

Taxonomy[edit]

Apart from the universally acceptedChamaerops humilis,there are a few potential taxa of unresolved status, plus numerous speciessynonymisedunderChamaerops humilis.[5]The genusChamaeropsis closely related to the genusTrachycarpus.The genera differ in thatTrachycarpuslacks the clumpinghabit(only forms single stems without basal suckers), the spiny leaf stems (spineless inTrachycarpus), and in small details of the flower anatomy.

Subspecies[edit]

The speciesChamaerops humilisitself has three acceptedvarietiesas follows:[6]

  • Chamaerops humilisvar.argenteaAndré(syn.C. h.var.cerifera) – "Atlas mountain palm" of Northwest Africa. Leaves glaucous.
  • Chamaerops humilisvar.epondraes– Northwest Africa. Leaves glaucous.
  • Chamaerops humilisvar.humilis– Southwest Europe. Leaves green.

There also are at least threecultivars:C. humilisvar.humilis'Nana',C. humilis'Vulcano', andC. humilis'Stella'.[7]C. humilis'Vulcano' is a compact, thornlesscultivarthat may be silvery, but less so thanargentea.The leaves tend to be thicker, and the appearance of the plant is bushier than var.humilisor var.argentea.

Description[edit]

Chamaerops humilisvar.argentea,south slopes of theHigh Atlas,Morocco. Zoom in to see the spines on the petioles.

Chamaerops humilisis ashrub-like clumping palm, with several stems growing from a single base. It has an undergroundrhizomewhich produces shoots with palmate,sclerophyllousleaves.

The stems grow slowly and often tightly together, eventually reaching 2–5 m (10–20 ft) tall with a trunk diameter of 20–25 cm (8–10 in). It is afan palm(Arecaceae tribe Corypheae), and as such, hasleaveswithpetiolesterminating in rounded fans of 10–20 leaflets. Each leaf is up to 1.5 m (5 ft) long, with leaflets 50–80 cm (20–30 in) long. The petioles are armed with numerous sharp, needle-like spines; these may protect the stem growing point from browsing animals.

Theflowersare borne in dense, shortinflorescencesat the tops of the stems. The plants usually, but not invariably, aredioeciouswith male and female flowers on separate plants. Theprophyllcovers the flowers on the inflorescence until the sexual phase (anthesis) and then splits open apically into two triangular lobes. The number of flowers per inflorescence is highly variable for both male and female plants, depending on the size of the inflorescence. Female flowers are tri-ovulate.[8]Unripefruitsare bright green, turning to dull yellow to brown as they ripen during autumn (September–November). The seed (usually0.6–0.8 g or1⁄50–3⁄100oz) contains a small cylindrical embryo, which is surrounded by several layers, from inner to outer as follows:

  • a nutritious endosperm,
  • a wide woody layer or endocarp,
  • a fleshy and fibrous mesocarp (the pulp), and
  • the thin outer layer or exocarp.[9]

Distribution[edit]

Chamaerops humilisis one of only two palm speciesnativeto continentalEurope,the other beingPhoenix theophrasti.It is mainly found in southwestern Europe, over all the south coasts ofSpainandPortugal,central and southernItaly,parts of the southern Mediterranean coast ofFranceandMonaco,on the islands ofMalta,Sicily,Sardinia,Corsica,and theBalearic Islands,[10]as well asNorth AfricainMorocco,AlgeriaandTunisia.[6][11]It is one of the northernmost naturally occurring palms in the world, with thenorthernmostnative standing inGenoa,Italy, at 44°N.[12]Although not naturally occurring far north from the Mediterranean,Chamaerops humilisgrows well as far north as southernEngland.

Cultivation[edit]

Chamaerops humilisis valued in gardening and landscaping in many parts of the world. It is very drought-tolerant once established. It is hardy to −12 °C (10 °F), but does prefer hot summers. It is a very slow-growing plant. A blue form of the species, native to high elevations of theAtlas Mountains,has recently been introduced into the trade and early reports indicate that it may be 12 °C (22 °F) or more hardier than the green form.[13]

It has gained theRoyal Horticultural Society'sAward of Garden Merit.[14]

Ecology[edit]

Derelomus chamaeropsis,aweevil,is the only known significant insect pollinator ofChamaerops humilis.[8]
In southern Spain, the Eurasian badgerMeles melesis the main seed disperser ofC. humilis[15]

Chamaerops humilishas a wide distribution in uncultivated land, and it is adapted to regimes of frequent burning, which it survives largely by re-sprouting from underground rhizomes and from fire-damaged stems. Such factors make the species ecologically important in preventingerosionanddesertificationand in providing shelter and food to many species of animals.

Chamaerops humilisflowers in spring, typically from April to May. The plant also may be partlyanemophilous(wind-pollinated), but it is at least partlyentomophilous(insect-pollinated). Only one insect species is known to pollinate it, namely a specific weevil,Derelomus chamaeropsis,in the familyCurculionidae.[16]The nature of the relationship with the weevil is a version ofnursery pollinationmutualismwith the weevil; the form this takes is that once pollinating weevils have found a satisfactory plant, whether male or female, they usually stay on the same plant until the end of its anthesis, finding shelter, egg-laying sites, and food in the inflorescences.[17]

Atanthesis,as is common inangiosperms,both male and femaleChamaerops humilisplants attract their pollinators with chemical compounds, but an unusual feature is that their scents are released by the leaves, and not by the flowers.[18]Towards the end of anthesis, weevils leave the plant and seek a new host plant, again either male or female.

Larval development of the weevilDerelomus chamaeropsisoccurs withinrachisesof inflorescences of male plants during autumn and winter. At the beginning of the next flowering period, adult weevils emerge from the dry and brittle stems of old inflorescences of the previous year of male plants only. Those that hatch in female plants die without concluding their development. This is because the palmettos are adapted to prevent the pollinating weevils from destroying the female inflorescences with their burden of seed. Weevils have been shown to lay eggs within female inflorescences, but as soon as seeds start to develop, eggs or larvae fail to continue their life cycle. On the other hand, male inflorescences have completed their function after pollination, so it is advantageous to the plant's reproduction for the weevils to complete their life cycles and shelter in the male inflorescences, thereby remaining available for pollination when they emerge in the following season.[19]

The ripe pulp ofC. humilishas several important functions.[20]

  • When ripened, the pulp smells strongly of rancid butter[21]and thus acts as a foraging cue for nocturnalfrugivoresthat commonly are fundamentally carnivorous mammals such as badgers and foxes.
  • The pulp inhibits germination, ensuring that the seed does not germinate until it has been dispersed.
  • The pulp also acts as a chemical or physical barrier against invertebrate seed predators, typically beetles, and in particular weevils.

Because of the combination of such functions in the pulp, the palm both benefits and suffers adverse consequences when carnivores feed on the fruit and thereby remove the pulp. On the one hand, the seeds that carnivores swallow, germinate more frequently than seeds in entire fruit. On the other hand, ingested seeds are more frequently destroyed by invertebrate pests than non-ingested seeds. However, because of the mobility of carnivores, their dispersal service is important to the palmetto, given the severe fragmentation and isolation of most populations across the increasingly densely populated Mediterranean basin.

The fungusConiothyrium palmarumwhich has been found associated with leaf spots onPhoenix dactylifera(Arecaceae) in India and Cyprus, has been found on a deadpetiole(leaf stalk) ofChaemerops humilis(Arecaceae) in Italy.[22]

Uses[edit]

Apart from its material benefits, this palmetto is of emotional value as a charismatic component of the "garrigues"and"macchias"of the Mediterranean coastline.

The leaves of the adult plants have been used to make brooms and for weaving mats, carrier baskets, and similar articles. For finer work the young, unopened leaves are treated withsulphurto soften them and provide supple fibre.

The husk, known in southern Spain as "higa", is edible before it becomes too tough to eat as it matures. Because of their bitterness and high tannin content, the fruit are not used for human food, but in traditional medicine they have been used as anastringent.[23]

Conservation[edit]

Urbanization and other human activities are making such rapid inroads into the natural habitat of the palm that they are raising concerns about the future of the species and its environment. Accordingly, there is an increase in regulations to protect both its stands and those of associated Mediterranean endemics.

Another conservation problem is that particularly in the northernmost parts of its natural range,Chamaerops humilisis seriously threatened by an introduced South AmericanmothPaysandisia archon.[24][25]Also, this Mediterranean native palm is affected by the introduction of related ornamental species because of the concurrent introduction of seed predators (such asCoccotrypes dactyliperdaandDactylotrypes longicollis) that feed on both the introduced and native palms.[26]

Gallery[edit]

  • Group of European fan palms in Menton, Alpes-Maritimes, France
    Group of European fan palms inMenton,Alpes-Maritimes,France
  • Female flowers
    Female flowers
  • Male flowers
    Male flowers
  • Chamaerops humilis growing in Mallorca
    Chamaerops humilisgrowing inMallorca
  • Chamaerops humilis silver form in Largo, Florida
    Chamaerops humilissilver form inLargo,Florida
  • Mature fruit, close-up
    Mature fruit, close-up
  • Very old clump of Chamaerops humilis in Phoenix, Arizona
    Very old clump ofChamaerops humilisin Phoenix, Arizona
  • Frond
    Frond
  • Chamaerops cerifera in the High Atlas Mountains
    Chamaerops ceriferain the High Atlas Mountains

References[edit]

  1. ^Gardiner, L.M.; Véla, E. (2017)."Chamaerops humilis".IUCN Red List of Threatened Species.2017:e.T13164373A95532812.doi:10.2305/IUCN.UK.2017-3.RLTS.T13164373A95532812.en.Retrieved19 November2021.
  2. ^Hook. f. Rep. Progr. Condition Roy. Bot. Gard. Kew 1882: 64 1884
  3. ^Herrera, J. 1989. On the reproductive biology of the dwarf palm, Chamaerops humilis, in southern Spain.
  4. ^S. H. Jenkins (2 October 2013).Mediterranean Coastal Pollution: Proceedings of a Conference Held in Palma, Mallorca, 24-27 September, 1979.Elsevier. pp. 489–.ISBN978-1-4831-5107-6.
  5. ^"The Plant List Version 1.1".2013.Retrieved14 April2016.
  6. ^abWCSP, World Checklist of Palms:ChamaeropsArchived19 February 2007 at theWayback Machine
  7. ^"RHS advice & tips on garden & indoor plants Plant finder & selector / RHS Gardening".Retrieved3 January2017.
  8. ^abDufay M. 2010. Impact of plant flowering phenology on the cost/benefit balance in a nursery pollination mutualism, with honest males and cheating females. J Evol Biol 23:977-86.
  9. ^Hasnaoui, O., M. Bouazza, and M. Thinon. 2009. Kinetical germination study of the Chamaerops humilis L. var. argentea Andre (Arecaceae). Environmental Research Journal 3:76–80.
  10. ^"Servei de Gestió Forestal-Chamaerops humilis".
  11. ^Euro+Med Plantbase Project:Chamaerops humilisArchived18 July 2011 at theWayback Machine
  12. ^Orsino, Francesco; Olivari, Silvia (1987)."La presenza di Chamaerops humilis L. Sul promontorio di Portofino (Liguria orientale)".Webbia.41(2): 261–272.doi:10.1080/00837792.1987.10670414.
  13. ^RHS A-Z encyclopedia of garden plants.United Kingdom: Dorling Kindersley. 2008. p. 1136.ISBN978-1405332965.
  14. ^"RHS Plant Selector -Chamaerops humilis".Retrieved15 April2020.
  15. ^Fedriani, J.M., and M. Delibes. 2011. Dangerous liaisons disperse the Mediterranean dwarf palm: fleshy-pulp defensive role against seed predators. Ecology 92:304–315.
  16. ^Dufay M. 2010
  17. ^Pat Willmer (25 July 2011).Pollination and Floral Ecology.Princeton University Press. pp. 565–.ISBN978-0-691-12861-0.
  18. ^Dufay, M., Anstett, M.-C. & Hossaert-McKey, M. 2003. When leaves act like flowers: how dwarf palms attract their pollinators. Ecol. Lett. 6: 28–34.
  19. ^Dufay, M. & Anstett, M.-C. 2004. Cheating is not always punished: killer female plants and pollination by deceit in the dwarf palm Chamaerops humilis. J. Evol. Biol. 17: 862–868.
  20. ^Fedriani, J.M., and M. Delibes. 2011
  21. ^Herrera, J. 1989
  22. ^de Gruyter, J.; Woudenberg, J.H.C.; Aveskamp, M.M.; Verkley, G.J.M.; Groenewald, J.Z.; Crous, P.W. (June 2013)."Redisposition of phoma-like anamorphs in Pleosporales".Studies in Mycology.75:1–36.doi:10.3114/sim0004.PMC3713885.
  23. ^Merlo M.E., M.M. Aleman, J. Cabello, and J. Penas. 1993. On the Mediterranean Fan Palm (Chamaerops humilis). Principes 37: 151-8.
  24. ^Parcs Nationaux de France:Hyères-les-(ex)-PalmiersArchived20 March 2006 at theWayback Machine
  25. ^International Palm Society:Importation of Mature Palms: A Threat to Native and Exotic Palms in Mediterranean Countries?Archived30 December 2005 at theWayback Machine
  26. ^Rodríguez M, M. Delibes and JM Fedriani. 2014. Hierarchical levels of seed predation variation by introduced beetles on an endemic Mediterranean palm. PLOS One. DOI: 10.1371/journal.pone.0109867

External links[edit]

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