Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Agave americana
(century plant)

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Datasheet

Agave americana (century plant)

Summary

  • Last modified
  • 25 October 2018
  • Datasheet Type(s)
  • Invasive Species
  • Host Plant
  • Preferred Scientific Name
  • Agave americana
  • Preferred Common Name
  • century plant
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • A. americana is a large, rhizomatous succulent that grows in a wide range of habitats and soil types. Additionally, it is tolerant to salt spray, high temperatures, and extreme drought. Because this species spr...

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Pictures

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PictureTitleCaptionCopyright
Agave americana (century plant); habit. Pohakuokala Gulch, Maui, Hawaii, USA. August 2005.
TitleHabit
CaptionAgave americana (century plant); habit. Pohakuokala Gulch, Maui, Hawaii, USA. August 2005.
Copyright©Forest & Kim Starr-2005 - CC BY 4.0
Agave americana (century plant); habit. Pohakuokala Gulch, Maui, Hawaii, USA. August 2005.
HabitAgave americana (century plant); habit. Pohakuokala Gulch, Maui, Hawaii, USA. August 2005.©Forest & Kim Starr-2005 - CC BY 4.0
Agave americana (century plant); bolting. Kula, Maui, Hawaii, USA. April 2009.
TitleHabit
CaptionAgave americana (century plant); bolting. Kula, Maui, Hawaii, USA. April 2009.
Copyright©Forest & Kim Starr-2009 - CC BY 4.0
Agave americana (century plant); bolting. Kula, Maui, Hawaii, USA. April 2009.
HabitAgave americana (century plant); bolting. Kula, Maui, Hawaii, USA. April 2009.©Forest & Kim Starr-2009 - CC BY 4.0
Agave americana (century plant); flowering stalk. Olinda, Maui, Hawaii, USA. December 2010.
TitleFlowering stalk
CaptionAgave americana (century plant); flowering stalk. Olinda, Maui, Hawaii, USA. December 2010.
Copyright©Forest & Kim Starr-2010 - CC BY 4.0
Agave americana (century plant); flowering stalk. Olinda, Maui, Hawaii, USA. December 2010.
Flowering stalkAgave americana (century plant); flowering stalk. Olinda, Maui, Hawaii, USA. December 2010.©Forest & Kim Starr-2010 - CC BY 4.0
Agave americana (century plant); closed flowers. Olinda, Maui, Hawaii, USA. December 2010.
TitleFlowers
CaptionAgave americana (century plant); closed flowers. Olinda, Maui, Hawaii, USA. December 2010.
Copyright©Forest & Kim Starr-2010 - CC BY 4.0
Agave americana (century plant); closed flowers. Olinda, Maui, Hawaii, USA. December 2010.
FlowersAgave americana (century plant); closed flowers. Olinda, Maui, Hawaii, USA. December 2010.©Forest & Kim Starr-2010 - CC BY 4.0
Agave americana (century plant); open flowers. Olinda, Maui, Hawaii, USA. December 2010.
TitleFlowers
CaptionAgave americana (century plant); open flowers. Olinda, Maui, Hawaii, USA. December 2010.
Copyright©Forest & Kim Starr-2010 - CC BY 4.0
Agave americana (century plant); open flowers. Olinda, Maui, Hawaii, USA. December 2010.
FlowersAgave americana (century plant); open flowers. Olinda, Maui, Hawaii, USA. December 2010.©Forest & Kim Starr-2010 - CC BY 4.0
Agave americana (century plant); habit, with varigated leaves, planted as an ornamental. Note young plants at base. Makawao, Maui, Hawaii, USA. December 2006.
TitleHabit
CaptionAgave americana (century plant); habit, with varigated leaves, planted as an ornamental. Note young plants at base. Makawao, Maui, Hawaii, USA. December 2006.
Copyright©Forest & Kim Starr-2006 - CC BY 4.0
Agave americana (century plant); habit, with varigated leaves, planted as an ornamental. Note young plants at base. Makawao, Maui, Hawaii, USA. December 2006.
HabitAgave americana (century plant); habit, with varigated leaves, planted as an ornamental. Note young plants at base. Makawao, Maui, Hawaii, USA. December 2006.©Forest & Kim Starr-2006 - CC BY 4.0
Agave americana (century plant); varigated leaves, note large spines on leaf margins. Makawao, Maui, Hawaii, USA. December 2006.
TitleVarigated leaves
CaptionAgave americana (century plant); varigated leaves, note large spines on leaf margins. Makawao, Maui, Hawaii, USA. December 2006.
Copyright©Forest & Kim Starr-2006 - CC BY 4.0
Agave americana (century plant); varigated leaves, note large spines on leaf margins. Makawao, Maui, Hawaii, USA. December 2006.
Varigated leavesAgave americana (century plant); varigated leaves, note large spines on leaf margins. Makawao, Maui, Hawaii, USA. December 2006.©Forest & Kim Starr-2006 - CC BY 4.0

Identity

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Preferred Scientific Name

  • Agave americana L.

Preferred Common Name

  • century plant

Other Scientific Names

  • Agave altissima Zumagl.
  • Agave communis Gaterau
  • Agave complicata Trel. ex Ochot.
  • Agave cordillerensis Lodé & Pino
  • Agave felina Trel.
  • Agave fuerstenbergii Jacobi
  • Agave gracilispina (Rol.-Goss.) Engelm. ex Trel.
  • Agave ingens A.Berger
  • Agave melliflua Trel.
  • Agave milleri Haw.
  • Agave ornata Jacobi
  • Agave picta Salm-Dyck
  • Agave rasconensis Trel.
  • Agave subtilis Trel.
  • Agave subzonata Trel.
  • Agave theometel Zuccagni
  • Agave zonata Trel.
  • Aloe americana (L.) Crantz

International Common Names

  • English: agave; American agave; American aloe
  • Spanish: cabuya (Bolivia); henequen; maguey; penca; pita; pita comun
  • French: agave américain; agave d'Amérique; choca; faux aloès; pite
  • Chinese: long she lan
  • Portuguese: piteira; piteira-brava; piteira-de-boi

Local Common Names

  • Brazil: caroata-acu
  • Ecuador/Galapagos Islands: Cubuya negra; penco
  • Germany: Agave, Amerikanische; Agave, hundertjährige
  • Greece: alades; alas; lalas
  • Italy: pitta; zabbara; zammara
  • Portugal: aloé-dos-cem-anos ; pita; piteira; piteira-brava; piteira-de-boi
  • South Africa: garingboom; spreading century plant
  • Spain: agave americano; aloe americano; azabara; maguey Americano; pita; pitaco; pitera

EPPO code

  • AGVAM (Agave americana)

Summary of Invasiveness

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A. americana is a large, rhizomatous succulent that grows in a wide range of habitats and soil types. Additionally, it is tolerant to salt spray, high temperatures, and extreme drought. Because this species spread by seeds, but also vegetatively by bulbils and rhizomes, it has the potential to escape from cultivation and rapidly colonize disturbed sites, roadsides, bare sand and coastal areas (ISSG, 2016). Currently, A. americana is considered a serious environmental weed by the IUCN (ISSG, 2016) and it is listed as invasive in many countries in Europe as well as in China, Japan, South Africa, Namibia, Tanzania, Bermuda, Australia, New Zealand, and New Caledonia among others (BioNET-EAFRINET, 2016; ISSG, 2016; DAISIE, 2016; PIER, 2016; Weeds of Australia, 2016). It is also known to have become invasive in Ethiopia, Kenya, Malawi, Rwanda, and Uganda.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Liliales
  •                         Family: Agavaceae
  •                             Genus: Agave
  •                                 Species: Agave americana

Notes on Taxonomy and Nomenclature

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The family Asparagales includes about 153 genera and 2500 species that are distributed worldwide. This family is subdivided into seven subfamilies: Aphyllanthoideae, Agavoideae, Brodiaeoideae, Scilloideae, Lomandroideae, Asparagoideae, and Nolinoideae. For some authors, the classification of this family is highly unsatisfactory. There are no specific traits that characterize this family, some of the subfamilies are difficult to recognize while others are very distinctive. Flowers for the most part are a rather undistinguished "lily"-type.

The subfamily Agavoideae, that comprises the genera Agave and Yucca, has been classified previously as a separate family, Agavaceae. The genus Agave includes about 220 species widespread in the tropical and subtropical regions of the world mainly in desert, dry and semiarid environments (Stevens, 2012). A. americana is a highly variable species, thus many “forms” have been treated as species, subspecies, and varieties (The Plant List, 2013).

A. americana was originally described by Linnaeus as one of the four members which he included in the genus Agave L. A. americana is the type species (generitype) of the genus Agave (Hitchcock, 1929). Two subspecies are widely recognized, A americana subsp. protamericana Gentry, and A. americana subsp. americana var. expansa (Jacobi) Gentry (Reveal and Hodgson, 2002). Although the species is given the common name century plant, derived from the long time it takes to flower, it typically only lives 10-30 years.

Description

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Plants acaulescent or short-stemmed, commonly suckering, trunks less than 2 m; rosettes not cespitose, 10–20 × 20-37 dm. Leaves erect, spreading to ascending, occasionally reflexed, 80–200 × 15-25 cm; blade light green to green or glaucous-gray, sometimes variegated or cross-zoned, narrowly to broadly lanceolate, smooth, rigid; margins nearly straight or undulate to crenate, armed, teeth single, 5-10 mm, 1-4 cm apart; apical spine dark brown to grayish, conical or subulate, 2-6 cm. Scape 5-9 m. Inflorescences paniculate, not bulbiferous; bracts persistent, triangular, 5-15 cm; lateral branches 15-35, horizontal to slightly ascending, comprising distal 1/3-1/2 of inflorescence, longer than 10 cm. Flowers erect, 7-10.5 cm; perianth yellow, tube funnelform to cylindric, 8-20 × 12-20 mm, limb lobes erect, subequal, 20-35 mm; stamens long-exserted; filaments inserted above mid perianth tube, erect, yellow, 6-9 cm; anthers yellow, 25-35 mm; ovary 3-4.5 cm, neck constricted, 3-6(-8) mm. Capsules short-pedicellate, oblong, 3.5-8 cm, apex beaked. Seeds 6-8 mm (Flora of North America Editorial Committee, 2016).

Plant Type

Top of page Broadleaved
Perennial
Seed propagated
Succulent
Vegetatively propagated

Distribution

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A. americana is native to North America. Native populations occur from the southern USA (i.e. Arizona and Texas) to northern and central Mexico (Govaerts, 2016; USDA-ARS, 2016). It has been distributed throughout the world for its ornamental value and now it can found naturalized in countries across Africa, Europe, Oceania, the Caribbean and Central and South America (Govaerts, 2016).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

BangladeshPresentIntroducedGovaerts, 2016
CambodiaPresentIntroducedGovaerts, 2016
ChinaPresentIntroducedWeber et al., 2008; Flora of China Editorial Committee, 2016Widely cultivated
IndiaPresentIntroducedGovaerts, 2016
JapanPresentIntroduced Invasive Toshiya, 2005
-Bonin IslandPresentIntroduced Invasive Toshiya, 2005
Korea, Republic ofPresentIntroducedGovaerts, 2016
MyanmarPresentIntroducedGovaerts, 2016
OmanPresentIntroducedISSG, 2016Established
PakistanPresentIntroducedGovaerts, 2016
PhilippinesPresentIntroducedISSG, 2016
SingaporePresentIntroducedChong et al., 2009Cultivated
Sri LankaPresentIntroducedISSG, 2016
ThailandPresentIntroducedGovaerts, 2016
TurkeyPresentIntroducedDAISIE, 2016Naturalized

Africa

AlgeriaPresentIntroducedGovaerts, 2016
BotswanaPresentIntroducedGovaerts, 2016
ChadPresentIntroducedGovaerts, 2016
EritreaPresentIntroducedGovaerts, 2016
EthiopiaPresentIntroduced Invasive Govaerts, 2016; Witt and Luke, 2017
GuineaPresentIntroducedGovaerts, 2016
KenyaPresentIntroduced Invasive Govaerts, 2016; Witt and Luke, 2017
LesothoPresentIntroducedGovaerts, 2016
LibyaPresentIntroducedGovaerts, 2016
MalawiPresentIntroduced Invasive Witt and Luke, 2017
MoroccoPresentIntroducedGovaerts, 2016
NamibiaPresentIntroduced Invasive Bethune et al., 2004
RéunionPresentIntroducedPIER, 2016
RwandaPresentIntroduced Invasive Govaerts, 2016; Witt and Luke, 2017
Saint HelenaPresentIntroducedGovaerts, 2016
SeychellesPresentIntroducedPIER, 2016
South AfricaPresentIntroduced Invasive Henderson, 2001
Spain
-Canary IslandsPresentIntroduced Invasive Arteaga et al., 2009; DAISIE, 2016
SwazilandPresentIntroducedGovaerts, 2016
TanzaniaPresentIntroduced Invasive BioNET-EAFRINET, 2016; Witt and Luke, 2017
TunisiaPresentIntroducedGovaerts, 2016
UgandaPresentIntroduced Invasive Witt and Luke, 2017
ZambiaPresentIntroducedWitt and Luke, 2017
ZimbabwePresentIntroducedISSG, 2016

North America

BermudaPresentIntroduced Invasive ISSG, 2016
MexicoPresentNativeGovaerts, 2016
USAPresentNativeUSDA-NRCS, 2016
-ArizonaPresentNativeUSDA-NRCS, 2016
-CaliforniaPresentNativeUSDA-NRCS, 2016
-FloridaPresentNativeUSDA-NRCS, 2016
-LouisianaPresentNativeUSDA-NRCS, 2016
-TexasPresentNativeUSDA-NRCS, 2016

Central America and Caribbean

Antigua and BarbudaPresentIntroducedAcevedo-Rodríguez and Strong, 2012
British Virgin IslandsPresentIntroducedAcevedo-Rodríguez and Strong, 2012Virgin Gorda
Cayman IslandsPresentIntroducedGovaerts, 2016
Costa RicaPresentIntroducedGovaerts, 2016
CubaPresentIntroducedGovaerts, 2016
Dominican RepublicPresentIntroducedGovaerts, 2016
GuadeloupePresentIntroducedAcevedo-Rodríguez and Strong, 2012
GuatemalaPresentIntroducedGovaerts, 2016
HaitiPresentIntroducedGovaerts, 2016
Puerto RicoPresent only in captivity/cultivationIntroducedAcevedo-Rodríguez and Strong, 2012
United States Virgin IslandsPresent only in captivity/cultivationIntroducedAcevedo-Rodríguez and Strong, 2012St John, St Thomas

South America

ArgentinaPresentIntroducedGovaerts, 2016
BoliviaPresentIntroducedGovaerts, 2016
ChilePresentIntroduced Invasive Danton et al., 2006Juan Fernandez Island
ColombiaPresentIntroducedGovaerts, 2016
EcuadorPresentIntroducedGovaerts, 2016
-Galapagos IslandsPresentIntroducedCharles Darwin Foundation, 2008Cultivated
PeruPresentIntroducedGovaerts, 2016

Europe

AlbaniaPresentIntroducedGovaerts, 2016
CroatiaPresentIntroducedISSG, 2016
CyprusPresentIntroducedDAISIE, 2016Naturalized
FrancePresentIntroducedDAISIE, 2016Naturalized
-CorsicaPresentIntroducedDAISIE, 2016Naturalized
GreecePresentIntroduced Invasive Arianoutsou et al., 2010
ItalyPresentIntroduced Invasive Celesti-Grapow et al., 2009
-SardiniaPresentIntroduced Invasive Brundu et al., 2003
-SicilyPresentIntroducedDAISIE, 2016Naturalized
MaltaPresentIntroduced Invasive DAISIE, 2016
NetherlandsPresentIntroducedISSG, 2016
PortugalPresentIntroduced Invasive DAISIE, 2016
-AzoresPresentIntroduced Invasive Silva et al., 2008
-MadeiraPresentIntroduced Invasive Silva et al., 2008
SpainPresentIntroduced Invasive Dana et al., 2003
-Balearic IslandsPresentIntroducedDAISIE, 2016Naturalized
SwitzerlandPresentIntroducedDAISIE, 2016Naturalized
UKPresentIntroducedDAISIE, 2016
-Channel IslandsPresentIntroducedDAISIE, 2016
Yugoslavia (former)PresentIntroducedGovaerts, 2016

Oceania

AustraliaPresentIntroducedWeeds of Australia, 2016
-Australian Northern TerritoryPresentIntroducedWeeds of Australia, 2016
-Lord Howe Is.PresentIntroduced Invasive Weeds of Australia, 2016
-New South WalesPresentIntroduced Invasive Weeds of Australia, 2016
-QueenslandPresentIntroduced Invasive Weeds of Australia, 2016
-South AustraliaPresentIntroducedWeeds of Australia, 2016
-TasmaniaPresentIntroducedWeeds of Australia, 2016
-VictoriaPresentIntroducedWeeds of Australia, 2016
-Western AustraliaPresentIntroduced Invasive Weeds of Australia, 2016
Cook IslandsPresentIntroducedMcCormack, 2013
FijiPresentIntroducedPIER, 2016
French PolynesiaPresentIntroducedFlorence et al., 2013Cultivated
GuamPresentIntroducedPIER, 2016
KiribatiPresentIntroducedPIER, 2016
NauruPresentIntroducedPIER, 2016
New CaledoniaPresentIntroduced Invasive MacKee, 1994
New ZealandPresentIntroduced Invasive Weeds of New Zealand, 2016
Norfolk IslandPresentIntroduced Invasive Orchard, 1994
Northern Mariana IslandsPresentIntroducedPIER, 2016
PalauPresentIntroduced Invasive PIER, 2016
TongaPresentIntroducedPIER, 2016
Wallis and Futuna IslandsPresentIntroducedPIER, 2016

History of Introduction and Spread

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A. americana has been widely introduced throughout the world for its ornamental value. However, because it is very difficult to collect, herbarium records probably greatly underestimate the actual distribution of this species in areas outside its native distribution range (PROTA, 2016; USDA-ARS, 2016; Weeds of Australia, 2016). It is believed that A. americana arrived in Europe around 1520, and the first description of this species in Europe was made by J.A. Cortoses in 1561, growing at Padua in northern Italy (Sydow, 1987).

On the Canary Islands, A. americana was introduced from Central America probably during the sixteenth century, and it is now widespread on most of the islands (Rodríguez et al., 2015). In continental Spain, several species of Agave, including A. americana were introduced in the 1940s as ornamental and cultivated plants, and now these species are spreading into new habitats, mainly on coastal sandy soils (Badano and Pugnaire, 2004).

In South Africa the plant was introduced in the 1960s and now it is spreading across the Western Cape, Eastern Cape, KwaZulu-Natal, Free State, Northern Cape, Limpopo, and Mpumalanga and is listed as invasive within the Kruger National Park (Invasive Species South Africa, 2016).

A. americana is widely cultivated and can be found naturalized and spreading in many parts of Australia including Queensland, Western Australia, New South Wales, Victoria and south-eastern South Australia. It is also naturalized on Lord Howe Island and Norfolk Island (Weeds of Australia, 2016).

In Puerto Rico and the Virgin Islands, A. americana is cultivated as an ornamental, but apparently is not yet naturalized (Acevedo-Rodríguez and Strong, 2005).

Risk of Introduction

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The risk of new introductions of A. americana is very high. This species is widely commercialized around the world for its ornamental value. Additionally, it has the potential to spread by seeds, daughter plants, and stem fragments which are easily carried to new sites by ocean tides, deliberate plantings, soil movement, and dumped vegetation (Weeds of Australia, 2016; Weeds of New Zealand, 2016).

Habitat

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In areas within and outside its native distribution range, A. americana can be found growing on cliffs, urban areas, woodlands, grasslands, riparian zones, beaches, sandy areas, and rocky slopes (DAISIE, 2016; ISSG, 2016; PROTA, 2016; Weeds of Australia, 2016; Weeds of New Zealand, 2016).

In Portugal and Spain, it grows in littoral areas and warm and dry areas throughout hedges, valleys, slopes, cliffs, stony, arid and sandy places, and along roadsides (DAISIE, 2016). In New Zealand, this species can be found spreading on estuarine and other coastal areas such as cliffs, bluffs, rocky areas, and inshore islands (Weeds of New Zealand, 2016). In Australia, it is often naturalized around old habitations and along roadsides in temperate, sub-tropical and semi-arid regions. It also grows in pastures, grasslands, open woodlands, coastal habitats and along watercourses (Weeds of Australia, 2016).

Habitat List

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CategoryHabitatPresenceStatus
Littoral
Coastal areas Present, no further details Harmful (pest or invasive)
Coastal areas Present, no further details Natural
Coastal areas Present, no further details Productive/non-natural
Coastal dunes Present, no further details Harmful (pest or invasive)
Coastal dunes Present, no further details Natural
Coastal dunes Present, no further details Productive/non-natural
Terrestrial-managed
Disturbed areas Present, no further details Harmful (pest or invasive)
Disturbed areas Present, no further details Natural
Disturbed areas Present, no further details Productive/non-natural
Rail / roadsides Present, no further details Harmful (pest or invasive)
Rail / roadsides Present, no further details Natural
Rail / roadsides Present, no further details Productive/non-natural
Urban / peri-urban areas Present, no further details Harmful (pest or invasive)
Urban / peri-urban areas Present, no further details Natural
Urban / peri-urban areas Present, no further details Productive/non-natural
Terrestrial-natural/semi-natural
Arid regions Present, no further details Natural
Natural forests Present, no further details Harmful (pest or invasive)
Natural forests Present, no further details Natural
Natural forests Present, no further details Productive/non-natural
Natural grasslands Present, no further details Harmful (pest or invasive)
Natural grasslands Present, no further details Natural
Natural grasslands Present, no further details Productive/non-natural
Rocky areas / lava flows Present, no further details Harmful (pest or invasive)
Rocky areas / lava flows Present, no further details Natural
Rocky areas / lava flows Present, no further details Productive/non-natural
Scrub / shrublands Present, no further details Harmful (pest or invasive)
Scrub / shrublands Present, no further details Natural
Scrub / shrublands Present, no further details Productive/non-natural

Hosts/Species Affected

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A. americana negatively impacts populations of native and endangered plant species such as Cheirolophus crassifolius and Cremnophyton lanfrancoi on Malta and species such as Crambe wildpretii, Crambe pritzelii, and Asparagus arborescens on the Canary Islands (ISSG, 2016).

Biology and Ecology

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Genetics

Various chromosome numbers have been reported for A. americana. Nonetheless, the species is a polyploid complex based on x = 30 with reports 2n = 60, 120, and 180 (Flora of North America Editorial Committee, 2016). Hybrids in the genus Agave are known, some of them being well documented. Concerning A. americana s.l., hybrids are known with A. asperrima Jacobi, A. salmiana Otto ex Salm-Dick, and A. scabra Ortega.

Reproductive Biology

A. americana is a monocarpic species. Plants produce flowers only once, at the end of their life-cycle after which they die (Nobel, 1988). The flowers are hermaphrodite and are pollinated by bats, birds, and insects (ISSG, 2016). A. americana also has clonal mechanisms of reproduction. Plants produce plantlets (daughter plants) and rhizomes and suckers are developed from sterile meristems (Nobel, 1988; Weeds of Australia, 2016). The reproduction via suckers allows the plant to spread laterally and form very large and dense colonies over time (BioNET-EAFRINET, 2016).

Physiology and Phenology

A. americana is a CAM species with characteristic nocturnal stomatal opening and tissue succulence. These traits that have allow this species to colonize water-stressed habitats such as deserts and dry grasslands (Nobel, 1988).

Most Agave species are monocarpic and deplete their sugar reserves to produce a huge quantity of seeds with high germination capacity and high establishment rates on sandy soils (Nobel, 1988; Badano and Pugnaire, 2004). Flowering time for A. americana is from spring to summer, varying among the infraspecific taxa in the native distribution area: subsp. protoamericana in early spring-early summer, subsp. americana var. americana in mid spring-early summer, subsp. americana var. expansa in late spring-early summer (Reveal and Hodgson, 2002). Out of its native range, A. americana s.l. has a flowering time during summer (July-August).

Longevity

A. americana is a robust, perennial and long-lived succulent plant (Nobel, 1988; DAISIE, 2016). The plant typically lives between 10 and 30 years (BioNET-EAFRINET, 2016).

Associations

Within its native range, in southern USA and Mexico, Agave species have great ecological importance, since they are main components of arid and semiarid ecosystems and are major food sources for Leptonycteris bats on their migratory routes across the Sonoran Desert and Mexico (Delgado-Lemus et al., 2014). In areas outside its native range, such as the island of Tenerife (Canary Islands, Spain), native species of birds such as Fringilla coelebs, Corvus corax, Cyanistes teneriffae, Phylloscopus canariensis, Regulus regulus, and Serinus canaria have been recorded foraging on inflorescences of A. americana (Rodríguez et al., 2015).

Environmental Requirements

A. americana grows in dry and semiarid habitats at elevations from sea level up to 2500 m. It tolerates extreme drought, salt spray, high temperatures, poor soil and low fertility (Weeds of New Zealand, 2016). It can grow on sandy and loamy soils, but prefers well-drained soil with pH ranging from 5.6 to 6.5 (PROTA, 2016). It can colonize bare sand, but cannot grow in shaded conditions (ISSG, 2016; Weeds of Australia, 2016).

Climate

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ClimateStatusDescriptionRemark
Am - Tropical monsoon climate Tolerated Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Tolerated < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
BS - Steppe climate Preferred > 430mm and < 860mm annual precipitation
BW - Desert climate Preferred < 430mm annual precipitation
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Tolerated Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)
Cf - Warm temperate climate, wet all year Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year

Air Temperature

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Parameter Lower limit Upper limit
Absolute minimum temperature (ºC) -3
Mean annual temperature (ºC) 10 30
Mean maximum temperature of hottest month (ºC) 40

Rainfall

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ParameterLower limitUpper limitDescription
Dry season duration04number of consecutive months with <40 mm rainfall
Mean annual rainfall100700mm; lower/upper limits

Rainfall Regime

Top of page Bimodal
Uniform

Soil Tolerances

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Soil drainage

  • free

Soil reaction

  • acid
  • neutral

Soil texture

  • light
  • medium

Special soil tolerances

  • infertile

Means of Movement and Dispersal

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A. americana spreads by seeds, which can be dispersed by both wind and water, and vegetatively via rhizomes and suckers. Daughter plants, seeds and stem fragments are carried to new sites by ocean tides, by deliberate plantings, soil movement especially down banks, dumped vegetation, and naturally as garden escapes (ISSG, 2016; Weeds of Australia, 2016, Weeds of New Zealand, 2016). Plants are most commonly spread into bushland areas in dumped garden waste (BioNET-EAFRINET, 2016).

Pathway Causes

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CauseNotesLong DistanceLocalReferences
Botanical gardens and zoosBotanical gardens Yes Yes USDA-NRCS, 2016
Escape from confinement or garden escapeSeeds, bulbils and stem fragments escaped from cultivation Yes Yes DAISIE, 2016
Escape from confinement or garden escapeSeeds, bulbils and stem fragments escaped from cultivation Yes Yes Weeds of Australia, 2016
Garden waste disposalSeeds, bulbils and stem fragments in dumped garden waste Yes Yes DAISIE, 2016
Garden waste disposalSeeds, bulbils and stem fragments in dumped garden waste Yes Yes Weeds of Australia, 2016
Habitat restoration and improvementSometimes planted to control erosion Yes Yes USDA-ARS, 2016
Hedges and windbreaksPlanted to create natural hedges Yes Yes PROTA, 2016
HorticultureWidely commercialized as ornamental Yes Yes USDA-ARS, 2016
Landscape improvementWidely commercialized as ornamental Yes Yes USDA-ARS, 2016
Medicinal useLeaves and sap used in traditional medicine Yes Yes USDA-ARS, 2016
Ornamental purposesWidely planted as ornamental Yes Yes USDA-ARS, 2016

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Debris and waste associated with human activitiesSeeds, bulbils and stem fragments in dumped garden waste Yes Yes DAISIE, 2016
Debris and waste associated with human activitiesSeeds, bulbils and stem fragments in dumped garden waste Yes Yes Weeds of Australia, 2016
Floating vegetation and debrisSeeds, bulbils and stem fragments Yes Yes Weeds of Australia, 2016
Soil, sand and gravelSeeds, bulbils and stem fragments Yes Yes Weeds of Australia, 2016
Land vehiclesSeeds, bulbils and stem fragments Yes Yes Weeds of Australia, 2016
WaterSeeds, bulbils and stem fragments Yes Yes Weeds of Australia, 2016
WindSeeds, bulbils and stem fragments Yes Yes Weeds of Australia, 2016

Impact Summary

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CategoryImpact
Cultural/amenity Positive and negative
Economic/livelihood Positive and negative
Environment (generally) Positive and negative
Human health Negative

Economic Impact

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The prickles along the leaf margins and sharp spines on the tips of the leaves can cause injury to people and animals (both domestic livestock and native animals). Large clumps can have an impact on pastures, as these dense colonies can prevent the growth of more suitable species and restrict the access of livestock (BioNET-EAFRINET, 2016; ISSG, 2016; Weeds of New Zealand, 2016).

Environmental Impact

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A. americana is regarded as an environmental weed and invasive species in many countries in Europe as well as in China, Japan, South Africa, Namibia, Tanzania, Bermuda, Australia, New Zealand, and New Caledonia (BioNET-EAFRINET, 2016; ISSG, 2016; DAISIE, 2016; PIER, 2016; Weeds of Australia, 2016). The species grows forming dense almost impenetrable thickets that displace native vegetation and inhibit the movement of native fauna (ISSG, 2016). One of the major impacts of A. americana is its large leaves shading out native plant species. It also has a very dense network of rhizome offshoots, which could draw resources away from native species. The rhizomatous nature of A. americana could also alter the nutrient status of the soil (ISSG, 2016).

Impact on Habitats

In New Zealand, A. americana is replacing vulnerable dune species. It also colonizes bare sand, causing build-ups of sand which can lead to new (usually exotic) habitats being formed and erosion elsewhere (Weeds of New Zealand, 2016). In South Africa, it is considered a noxious invasive weed and grows forming dense, almost impenetrable thickets that can cause injury to people and animals (Invasive Species South Africa, 2016). In Australia, A. americana is regarded as an environmental weed in Victoria, New South Wales, South Australia, Western Australia and Queensland, and is thought to pose a significant threat to rangeland biodiversity in Australia. Though this species grows and spreads slowly, and is largely seen as an invader of roadsides and disturbed sites, it is also found growing in natural vegetation and eventually forms dense almost impenetrable thickets (Weeds of Australia, 2016).

In coastal dune habitats in southern Spain, A. americana is one of the invasive plants listed as increasing in number and affecting the conservation of natural coastal ecosystems.

Impact on Biodiversity

On the island of Malta, A. americana is outcompeting and replacing critically endangered Cheirolophus crassifolius (the national plant of Malta) and the endangered Atriplex lanfancoi (formerly Cremnophyton lanfrancoi) (ISSG, 2016). On the Canary Islands, A. americana is an aggressive invader threatening species listed as critically endangered, endangered and vulnerable such as Crambe wildpretii, Crambe pritzelii and Asparagus arborescens (Arévalo et al. 2005; ISSG, 2016). On Tenerife in the Canary Islands, the native bird community uses A. americana as a feeding resource at a higher rate than it uses endemic plants, which could have positive effects on birds but negative impact on the pollination of invasive plants (Rodríguez et al., 2015).

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Crambe wildpretii (Col de Risco)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered)Canary IslandsCompetition - monopolizing resources; Competition - smotheringISSG, 2016
Crambe pritzelii (Col de Risco)EN (IUCN red list: Endangered) EN (IUCN red list: Endangered)Canary IslandsCompetition - monopolizing resources; Competition - smotheringISSG, 2016
Cheirolophus crassifolius (Maltese centaury)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered)Competition - monopolizing resources; Competition - smotheringISSG, 2016
Atriplex lanfrancoi (Maltese Cliff Orache)EN (IUCN red list: Endangered) EN (IUCN red list: Endangered)Competition - monopolizing resources; Competition - smotheringISSG, 2016
Helichrysum melitense (Maltese Everlasting)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered)Competition - monopolizing resources; Competition - smotheringISSG, 2016
Asparagus arborescensVU (IUCN red list: Vulnerable) VU (IUCN red list: Vulnerable)Canary IslandsCompetition - monopolizing resources; Competition - smotheringISSG, 2016

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
  • Pioneering in disturbed areas
  • Highly mobile locally
  • Benefits from human association (i.e. it is a human commensal)
  • Long lived
  • Gregarious
  • Reproduces asexually
Impact outcomes
  • Damaged ecosystem services
  • Ecosystem change/ habitat alteration
  • Modification of hydrology
  • Modification of successional patterns
  • Monoculture formation
  • Reduced amenity values
  • Reduced native biodiversity
  • Soil accretion
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Causes allergic responses
  • Competition - monopolizing resources
  • Competition - smothering
  • Poisoning
  • Rooting
  • Produces spines, thorns or burrs
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Difficult/costly to control

Uses

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Economic Value

A. americana has been widely commercialized for its ornamental value. This species is grown as an ornamental and hedge plant on all continents, except Antarctica (Nobel, 1988; USDA-ARS, 2016). A. americana is also used as a fodder, although it cannot be directly grazed and requires processing before feeding. The leaf fibres are sometimes used to make textiles (PROTA, 2016; USDA-ARS, 2016).

Social Benefit

In Mexico and South Africa, A. americana is used to brew an alcoholic liquor beverage (PROTA, 2016). It is also used in traditional medicine to treat to treat cardiac problems, high blood pressure, gastro-intestinal problems and rheumatic pain (PROTA, 2016; USDA-ARS, 2016).

Environmental Services

A. americana is used a hedge plant and planted along contours for erosion control and for reclamation of denuded and overgrazed land. (USDA-ARS, 2016).

Uses List

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Environmental

  • Agroforestry
  • Amenity
  • Boundary, barrier or support
  • Erosion control or dune stabilization
  • Landscape improvement
  • Soil conservation

General

  • Botanical garden/zoo
  • Sociocultural value

Human food and beverage

  • Beverage base
  • Honey/honey flora

Materials

  • Fibre
  • Poisonous to mammals

Medicinal, pharmaceutical

  • Traditional/folklore

Ornamental

  • garden plant
  • Propagation material

Similarities to Other Species/Conditions

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A. americana may be easily confused with other agave and hemp species such as Agave sisalana, Agave angustifolia, Furcraea foetida and Furcraea selloa. According to the website Weeds of Australia (2016), these species can be distinguished by the following differences:

  • A. americana has very large greyish or variegated leaves that are usually 1-2 m long on adult plants. These leaves have numerous, relatively large prickles (5-10 mm long) along their margins. Its flowers are borne in an upright position and are yellow or yellowish-green in colour. This species produces large capsules and usually doesn't develop plantlets (i.e. bulbils) on the branches of its flower clusters.

  • A. sisalana has relatively large dark green or greyish-green leaves that are usually 0.5-1.3 m long on adult plants. These leaves do not have any prickles on their margins. Its flowers are borne in an upright position and are yellow or yellowish-green in colour. This species usually doesn't produce capsules, instead developing numerous plantlets (i.e. bulbils) on the branches of its flower clusters.

  • A. angustifolia has relatively large green, greyish-green or variegated leaves that are usually 0.5-1 m long on adult plants. These leaves have many, relatively small prickles (2-5 mm long) along their margins. Its flowers are borne in an upright position and are yellow or yellowish-green in colour. This species produces large capsules and sometimes also develops plantlets (i.e. bulbils) on the branches of its flower clusters.

  • F. foetida has very large pale green leaves that are usually 1-2 m long on adult plants. These leaves usually have some prickles along their margins, but mainly near the bases of the leaves. Its flowers are borne in a drooping position and are whitish or greenish-white in colour. This species doesn't produce capsules, instead developing numerous plantlets (i.e. bulbils) on the branches of its flower clusters.

  • F. selloa has very large variegated leaves that are usually 1-2 m long on adult plants. These leaves have numerous relatively large prickles (7-8 mm long) along their margins. Its flowers are borne in a drooping position and are whitish or greenish-white in colour. This species doesn't produce capsules, instead developing numerous plantlets (i.e. bulbils) on the branches of its flower clusters.

Prevention and Control

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Control of A. americana is mainly achieved by using a combination of physical and chemical management techniques (ISSG, 2016). Using mechanical treatment to remove large individuals together with herbicides to control smaller plants delays invasion and allows recovery of natural vegetation (Arévalo et al., 2011). Combined mechanical and chemical control gave little recovery of the invasive plant four years after treatment in Tenerife (Arévalo et al., 2011).

Physical/Mechanical Control

Small infestations of A. americana can be controlled by digging out small plants manually. Large plants can be moved by machinery. Care should be taken to dig out the taproot to prevent spread by suckering, and all pieces need to be disposed of properly (Weeds of New Zealand, 2016).

Chemical Control

Large infestations of A. americana can be controlled by cutting down leaves close to the ground and painting the stump immediately with herbicide such as glyphosate and picloram + 2,4-D. Follow up treatment may be necessary, especially for larger plants (ISSG, 2016; Weeds of New Zealand, 2016).

References

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Contributors

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26//10/16 Updated by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

22/09/16 Original text by:

Duilio Iamonico, University of Rome Sapienza, Italy

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