Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Stachytarpheta cayennensis
(blue snakeweed)

Toolbox

Datasheet

Stachytarpheta cayennensis (blue snakeweed)

Summary

  • Last modified
  • 15 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Stachytarpheta cayennensis
  • Preferred Common Name
  • blue snakeweed
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae
  • Summary of Invasiveness
  • S. cayennensis is a shrub native to South and Central America and the Caribbean. It was introduced widely introduced into several tropical countries around the world as an ornamental species due to its attracti...

  • Principal Source
  • Draft datasheet under review

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report

Pictures

Top of page
PictureTitleCaptionCopyright
Stachytarpheta cayennensis (blue snakeweed); flowers. West Kuiaha Rd, Haiku, Maui, Hawaii, USA. November, 2006.
TitleFlowers
CaptionStachytarpheta cayennensis (blue snakeweed); flowers. West Kuiaha Rd, Haiku, Maui, Hawaii, USA. November, 2006.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); flowers. West Kuiaha Rd, Haiku, Maui, Hawaii, USA. November, 2006.
FlowersStachytarpheta cayennensis (blue snakeweed); flowers. West Kuiaha Rd, Haiku, Maui, Hawaii, USA. November, 2006.©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); flowering habit - all the darker areas are Stachytarpheta. East Poelua West Maui, Maui, Hawaii, USA. May, 2009.
TitleInvasive habit
CaptionStachytarpheta cayennensis (blue snakeweed); flowering habit - all the darker areas are Stachytarpheta. East Poelua West Maui, Maui, Hawaii, USA. May, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); flowering habit - all the darker areas are Stachytarpheta. East Poelua West Maui, Maui, Hawaii, USA. May, 2009.
Invasive habitStachytarpheta cayennensis (blue snakeweed); flowering habit - all the darker areas are Stachytarpheta. East Poelua West Maui, Maui, Hawaii, USA. May, 2009.©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); habit. Kilauea Pt NWR, Kauai, Hawaii, USA. March, 2013.
TitleHabit
CaptionStachytarpheta cayennensis (blue snakeweed); habit. Kilauea Pt NWR, Kauai, Hawaii, USA. March, 2013.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); habit. Kilauea Pt NWR, Kauai, Hawaii, USA. March, 2013.
HabitStachytarpheta cayennensis (blue snakeweed); habit. Kilauea Pt NWR, Kauai, Hawaii, USA. March, 2013.©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); leaves. Kipahulu LZ Haleakala National Park, Maui, Hawaii, USA. February, 2009.
TitleLeaves
CaptionStachytarpheta cayennensis (blue snakeweed); leaves. Kipahulu LZ Haleakala National Park, Maui, Hawaii, USA. February, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); leaves. Kipahulu LZ Haleakala National Park, Maui, Hawaii, USA. February, 2009.
LeavesStachytarpheta cayennensis (blue snakeweed); leaves. Kipahulu LZ Haleakala National Park, Maui, Hawaii, USA. February, 2009.©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); general habit. Note the long, 'snaking', inflorescenses. Loxahatchee National Wildlife Refuge, Florida, USA. September, 2009.
TitleHabit
CaptionStachytarpheta cayennensis (blue snakeweed); general habit. Note the long, 'snaking', inflorescenses. Loxahatchee National Wildlife Refuge, Florida, USA. September, 2009.
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Stachytarpheta cayennensis (blue snakeweed); general habit. Note the long, 'snaking', inflorescenses. Loxahatchee National Wildlife Refuge, Florida, USA. September, 2009.
HabitStachytarpheta cayennensis (blue snakeweed); general habit. Note the long, 'snaking', inflorescenses. Loxahatchee National Wildlife Refuge, Florida, USA. September, 2009.©Forest Starr & Kim Starr - CC BY 4.0

Identity

Top of page

Preferred Scientific Name

  • Stachytarpheta cayennensis (Rich.) Vahl

Preferred Common Name

  • blue snakeweed

Other Scientific Names

  • Stachytarpheta australis Moldenke
  • Stachytarpheta dichotoma (Ruiz Lopez & Pavon) Vahl
  • Stachytarpheta urticaefolia (Salisb.) Sims
  • Valerianoides cayennensis (Rich.) Kuntze
  • Verbena cayennensis Rich.

International Common Names

  • English: blue porterweed; blue rat's tail; bluetop; branched porterweed; brazilian tea; cayenne porterweed; cayenne snakeweed; false verbena; joee; nettleleaf porterweed; nettleleaf velvetberry; nettleleaf vervain; rattail; rough leaved false vervain
  • French: herbe à chenille; herbe bleue; queue de rat

Local Common Names

  • : piche de gato; rabo de zorro
  • Brazil: gervâo; gervao-urticante
  • Cook Islands: tiaki
  • Fiji: finak ne puak; lavenia; se karakarawa; serakawa; tumbutumbu; turulakaka
  • French Polynesia: piripiri
  • Japan: honagaso
  • Kiribati: te uti
  • Micronesia, Federated states of: ouchung; sakura
  • Nauru: edidubai; edidubaiy
  • Niue: mautofu samoa; motofu
  • Palau: louch beluu
  • Samoa: fua pepe; fua pepe; mautofu; mautofu tala; mautofu vao; taioti; vao pepe
  • Tonga: ‘i kuma; ‘iku ‘i kuma; hiku ‘i kuma
  • USA/Hawaii: oi; owi

EPPO code

  • STCHI (Stachytarpheta cayennensis)

Summary of Invasiveness

Top of page

S. cayennensis is a shrub native to South and Central America and the Caribbean. It was introduced widely introduced into several tropical countries around the world as an ornamental species due to its attractive blue flowers, but in some countries it has become invasive. S. cayennensis has a wide environmental tolerance and often invades disturbed areas where it can outcompete native flora. It is invasive in many Pacific islands and is regarded as a noxious weed in the Northern Territory, Australia and is increasing in abundance in Florida, USA. According to a risk assessment this species is regarded as being highly invasive (score 20 = high risk) (PIER, 2015).

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Lamiales
  •                         Family: Verbenaceae
  •                             Genus: Stachytarpheta
  •                                 Species: Stachytarpheta cayennensis

Notes on Taxonomy and Nomenclature

Top of page

S. cayennensis belongs to the Verbenaceae family which comprises around 100 genera. The genus Stachytarpheta has undergone a series of taxonomic revisions that are further complicated by putative hybrids (Wilson et al., 2009). A total of 32 synonyms of S. cayennensis, including varieties, have been reported (The Plant List, 2013). Further details of the taxonomic history can be found in Munir (1992).

A number of species within the genus Stachytarpheta are also known to be invasive weeds.

Stachy(s) (a spike, originally an ear of corn) describes the elongate inflorescence, and tarphy (thick) refers to the thickened or densely flowered flower stalks. The plant was named after the capital of French Guiana, Cayenne.

The genus Stachytarpheta contains about 65 species, mostly from the American tropics. Many of which are regarded as being weedy throughout the tropics and subtropics. The closely related species S. jamaicensis is similar in appearance to S. cayennensis and the common names for these species are often used interchangeably.

Description

Top of page

S. cayennensis is a perennial evergreen herb or subshrub which can reach heights of 2.5 m. It has a woody glabrous stem with several branches. Leaves opposite, membranous, elliptic to broadly elliptic or ovate, 4-8 cm long, 2-4.5 cm wide, upper surface rugose, both surfaces glabrous or occasionally lower surface with a few scattered hairs usually along the veins and margins, margins sharply and coarsely serrate, the teeth conspicuously divergent, apex acute, base cuneate, petioles 0.5-2 cm long. Spikes slender, rachis flexuous to erect or somewhat nodding, 14-40 cm long, ca. 2.5 mm in diameter, the furrows somewhat shallow, nearly as wide as the rachis, bracts lanceolate, ca. 7 mm long; calyx ca. 7 mm long, the teeth subequal; corolla usually dark purplish blue with a paler center, the tube 7-8 mm long (Wagner et al., 1999).

Distribution

Top of page

The native range of S. cayennensis includes much of the Americas, from Mexico, Central America and the Caribbean, through tropical South America to southern Brazil (Weeds of Australia, 2011).

This species has been introduced into all of the continents with tropical and subtropical climates between 30° N and 30° S parallels.

Distribution Table

Top of page

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

Chagos ArchipelagoPresentIntroducedTopp, 1988; Whistler, 1996; PIER, 2015Diego Garcia Island
ChinaPresentIntroducedMunir, 1992
Christmas Island (Indian Ocean)PresentIntroducedMunir, 1992; USDA-ARS, 2015
IndiaPresentIntroducedUSDA-ARS, 2015
IndonesiaPresentIntroducedHolm et al., 1979; PIER, 2015; USDA-ARS, 2015
JapanPresentIntroducedMito and Uesugi, 2004; PIER, 2015
MalaysiaPresentIntroducedUSDA-ARS, 2015
SingaporePresentIntroduced Invasive Chong et al., 2009; PIER, 2015
Sri LankaPresentIntroducedUSDA-ARS, 2015
TaiwanPresentHolm et al., 1979; PIER, 2015
ThailandPresentIntroducedHolm et al., 1979; PIER, 2015

Africa

CameroonPresentIntroducedUSDA-ARS, 2015
GhanaPresentIntroducedUSDA-ARS, 2015
LiberiaPresentIntroducedUSDA-ARS, 2015
MauritiusPresentIntroducedUSDA-ARS, 2015
MayottePresentIntroduced Invasive
MozambiquePresentIntroducedUSDA-ARS, 2015
NigeriaPresentIntroducedUSDA-ARS, 2015
RéunionPresentIntroduced Invasive Lavergne, 2006; PIER, 2015
SeychellesPresentIntroducedRobertson and Fosberg, 1983; Robertson and Fosberg, 1983; PIER, 2015Alphonse Island, Coetivy Island
Sierra LeonePresentIntroducedUSDA-ARS, 2015
UgandaPresentIntroducedUSDA-ARS, 2015
ZimbabwePresentIntroducedUSDA-ARS, 2015

North America

MexicoPresent, few occurrencesNativeTroncoso, 1979; Cowan, 1983; Sousa and Sanchez Cabrera, 1983; Pool and Rueda, 2001; Carnevali et al., 2010; Davidse et al., 2012; PIER, 2015; USDA-ARS, 2015Campeche, Chiapas, Quintana Roo, Tabasco, Veracruz, Yucatan
USAPresentPresent based on regional distribution.
-FloridaPresentIntroducedUSDA-ARS, 2015
-HawaiiPresentIntroduced Invasive PIER, 2015; USDA-ARS, 2015Hawaii, Kauai, Lanai, Maui, Molokai and Oahu islands

Central America and Caribbean

Antigua and BarbudaPresent, few occurrencesNativeUSDA-ARS, 2015
BarbadosPresent, few occurrencesNativeUSDA-ARS, 2015
BelizePresent, few occurrencesNativeUSDA-ARS, 2015
Costa RicaPresent, few occurrencesNativePIER, 2015; USDA-ARS, 2015
CubaPresent, few occurrencesNativeUSDA-ARS, 2015
DominicaPresent, few occurrencesNativeUSDA-ARS, 2015
Dominican RepublicPresent, few occurrencesNativeUSDA-ARS, 2015
El SalvadorPresentNativePIER, 2015
GrenadaPresent, few occurrencesNativeUSDA-ARS, 2015
GuadeloupePresent, few occurrencesNativeUSDA-ARS, 2015
GuatemalaPresent, few occurrencesNativeGibson, 1970; Davidse et al., 2012; PIER, 2015; USDA-ARS, 2015Alta Verapaz, Chimaltenango, Izabal, Petén
HaitiPresent, few occurrencesNativeUSDA-ARS, 2015
HondurasPresent, few occurrencesNativeNelson and Proctor, 1994; Davidse et al., 2012; PIER, 2015; USDA-ARS, 2015Islas de la Bahía
JamaicaPresent, few occurrencesNativeUSDA-ARS, 2015
MartiniquePresent, few occurrencesNativeUSDA-ARS, 2015
MontserratPresent, few occurrencesNativeUSDA-ARS, 2015
NicaraguaPresent, few occurrencesNativePool and Rueda, 2001; PIER, 2015; USDA-ARS, 2015
PanamaPresent, few occurrencesNativeGibson, 1970; Davidse et al., 2012; PIER, 2015; USDA-ARS, 2015Canal Area, Chiriquí, Coclé, Colón, Darién, Panamá, Veraguas
Puerto RicoPresent, few occurrencesNativeUSDA-ARS, 2015
Saint LuciaPresent, few occurrencesNativeUSDA-ARS, 2015
Saint Vincent and the GrenadinesPresent, few occurrencesNativeUSDA-ARS, 2015
Trinidad and TobagoPresent, few occurrencesNativeUSDA-ARS, 2015

South America

ArgentinaPresent, few occurrencesNativeTroncoso, 1979; Davidse et al., 2012Corrientes, Entre Rios, Jujuy, Misiones, Salta
BoliviaPresent, few occurrencesNativeFoster, 1958; Davidse et al., 2012; Jørgensen et al., 2014
BrazilPresent, few occurrencesNativeForzza R et al, 2010; Davidse et al., 2012
-AcrePresent, few occurrencesNativeUSDA-ARS, 2015
-AmapaPresent, few occurrencesNativeUSDA-ARS, 2015
-AmazonasPresent, few occurrencesNativeUSDA-ARS, 2015
-BahiaPresent, few occurrencesNativeUSDA-ARS, 2015
-CearaPresent, few occurrencesNativeUSDA-ARS, 2015
-GoiasPresent, few occurrencesNativeUSDA-ARS, 2015
-MaranhaoPresent, few occurrencesNativeUSDA-ARS, 2015
-Mato GrossoPresent, few occurrencesNativeUSDA-ARS, 2015
-Minas GeraisPresent, few occurrencesNativeUSDA-ARS, 2015
-ParaPresent, few occurrencesNativeUSDA-ARS, 2015
-ParanaPresent, few occurrencesNativeUSDA-ARS, 2015
-PernambucoPresent, few occurrencesNativeUSDA-ARS, 2015
-Rio de JaneiroPresent, few occurrencesNativeUSDA-ARS, 2015
-Rio Grande do SulPresent, few occurrencesNativeUSDA-ARS, 2015
-Sao PauloPresent, few occurrencesNativeUSDA-ARS, 2015
ChilePresentPresent based on regional distribution.
-Easter IslandPresentIntroduced Not invasive Meyer, 2007
ColombiaPresent, few occurrencesNativeIdárraga-Piedrahita et al., 2011; Davidse et al., 2012; USDA-ARS, 2015
EcuadorPresent, few occurrencesNativeWiggins and Porter, 1971; Dodson and Gentry, 1978; Lawesson et al., 1987; Renner et al., 1990; Davidse et al., 2012; USDA-ARS, 2015El Oro, Galapagos Islands, Guayas, Imbabura, Loja, Los Rios, Morona-Santiago, Napo, Pastaza, Pichincha, Zamora-Chinchipe
-Galapagos IslandsPresentIntroduced Invasive PIER, 2015Floreana, Isabela, San Cristobal and Santa Cruz islands
French GuianaPresent, few occurrencesNativeMunir, 1992; Funk et al., 2007; Davidse et al., 2012; USDA-ARS, 2015
GuyanaPresent, few occurrencesNativeUSDA-ARS, 2015
ParaguayPresent, few occurrencesNativeDavidse et al., 2012; USDA-ARS, 2015
PeruPresent, few occurrencesNativeVargas, 1943; Munir, 1992; Davidse et al., 2012; PIER, 2015; USDA-ARS, 2015Amazonas, Cajamarca, Cuzco, Huanuco, Junin, Loreto, Madre de Dios, San Martin, Ucayali
SurinamePresentNativeFunk et al., 2007; Davidse et al., 2012; USDA-ARS, 2015
VenezuelaPresent, few occurrencesNativeFunk et al., 2007; Hokche et al., 2008; Davidse et al., 2012; USDA-ARS, 2015Amazonas, Anzoátegui, Apure, Aragua, Barinas, Bolívar, Carabobo, Cojedes, Delta Amacuro, Distrito Federal, Guárico, Lara, Mérida, Miranda, Monagas, Nueva Esparta, Portuguesa, Sucre, Táchira, Trujillo, Yaracuy, Zulia

Oceania

American SamoaPresent, few occurrencesIntroduced Invasive Space and Flynn, 2000; Ragone and Lorence, 2003; USDA-ARS, 2015
AustraliaPresentIntroduced Invasive Munir, 1992; USDA-ARS, 2015
-Australian Northern TerritoryPresentIntroduced Invasive PIER, 2015; USDA-ARS, 2015
-QueenslandPresentIntroduced Invasive PIER, 2015; USDA-ARS, 2015
-Western AustraliaPresentIntroduced Invasive Munir, 1992
Cook IslandsPresentIntroducedPIER, 2015; USDA-ARS, 2015
FijiPresentIntroducedPIER, 2015; USDA-ARS, 2015
French PolynesiaPresentIntroduced Invasive PIER, 2015; USDA-ARS, 2015Mangareva, Hiva Oa, Tahuata, Ua Huka, Huahine, Moorea, Mopelia Atoll, Raiatea, Manuae, Taha'a, Tahiti, Tupai, Makatea, Niau Atoll, Rangiroa Atoll, Takapoto Atoll, Tikehau Atoll, Toau Atoll, Raivavae, Rapa, Rurutu and Tubuai islands
GuamPresentIntroducedUSDA-ARS, 2015
KiribatiPresent, few occurrencesIntroduced Invasive Fosberg et al., 1979; Wester, 1985; Fosberg and Stoddart, 1994; Space and Imada, 2004; PIER, 2015; USDA-ARS, 2015Gilbert Islands, Phoenix Islands, Line Islands
Marshall IslandsPresent, few occurrencesIntroduced Invasive Fosberg and Sachet, 1962; Fosberg et al., 1979; Lamberson, 1982; Fosberg, 1990; PIER, 2015
Micronesia, Federated states ofPresentIntroducedPIER, 2015; USDA-ARS, 2015
NauruPresent, few occurrencesIntroduced Invasive Thaman et al., 1994; PIER, 2015
New CaledoniaPresent, few occurrencesIntroduced Invasive MacKee, 1994; Gargominy et al., 1996; PIER, 2015; USDA-ARS, 2015
NiuePresent, few occurrencesIntroduced Invasive Fosberg et al., 1979; Whistler and Atherton, 1997; Space and Flynn, 2000; Space et al., 2009; PIER, 2015; USDA-ARS, 2015
Northern Mariana IslandsPresentIntroducedUSDA-ARS, 2015
PalauPresent, few occurrencesIntroduced Invasive Fosberg et al., 1979; Space et al., 2003; Space et al., 2009; PIER, 2015; USDA-ARS, 2015
Papua New GuineaPresentIntroducedMunir, 1992; PIER, 2015; USDA-ARS, 2015
SamoaPresent, few occurrencesIntroduced Invasive Space and Flynn, 2002; PIER, 2015
Solomon IslandsPresentIntroducedHancock et al., 1988; Swarbrick, 1997; PIER, 2015; USDA-ARS, 2015
TokelauPresentIntroducedSwarbrick, 1997
TongaPresent, few occurrencesIntroducedYuncker, 1959; PIER, 2015; USDA-ARS, 2015
TuvaluPresentIntroducedSwarbrick, 1997; PIER, 2015
VanuatuPresent, few occurrencesIntroduced Invasive Shine et al., 2003; PIER, 2015; USDA-ARS, 2015
Wake IslandPresent, few occurrencesIntroduced Invasive Fosberg and Sachet, 1969; PIER, 2015
Wallis and Futuna IslandsPresent, few occurrencesIntroduced Invasive Meyer, 2007; PIER, 2015

History of Introduction and Spread

Top of page

The majority of introductions throughout the world are as a result of intentional introductions for ornamental purposes. S. cayennensis produces an attractive blue flower which is appealing to bees and butterflies.

In 1868 S. cayennensis was introduced into New Caledonia as fooder for livestock (Blanfort et al., 2008).

Risk of Introduction

Top of page

The risk of S. cayennensis being introduced into new areas is fairly high as seeds of this species are readily available for sale on the internet. In addition to this, it can disperse locally by winds, attachment of seeds to vehicles and animals or as a contaminant in hay (Weeds of Australia, 2011). A risk assessment conducted by PIER (2015) gave this species a high score of 20 and therefore would reject its import due to its invasive tendencies.

Habitat

Top of page

S. cayennensis is common in open field like pastures, crop fields, moorlands, fallow lands, roadsides and wastelands. This species is also tolerant to shade and may invade low density forests. S. cayennensis grows on every type of soils, including infertile and dry soils. Although it can tolerate drought, this species grows best in moist, deep, fertile soils in disturbed areas (HEAR, 2012).

Habitat List

Top of page
CategorySub-CategoryHabitatPresenceStatus
Terrestrial
 
Terrestrial – ManagedCultivated / agricultural land Present, no further details Productive/non-natural
Managed forests, plantations and orchards Present, no further details
Managed grasslands (grazing systems) Present, no further details Productive/non-natural
Disturbed areas Principal habitat Natural
Rail / roadsides Present, no further details Harmful (pest or invasive)
Terrestrial ‑ Natural / Semi-naturalNatural forests Present, no further details
Natural grasslands Principal habitat Natural
Scrub / shrublands Present, no further details

Hosts/Species Affected

Top of page

S. cayennensis may outcompete smaller native plant species and crops dedicated to livestock are often affected by smothering. In Australia, this species is commonly found as a weed of pastures and sugarcane (Saccharum species) (DAFF, 2014).

Climate

Top of page
ClimateStatusDescriptionRemark
A - Tropical/Megathermal climate Preferred Average temp. of coolest month > 18°C, > 1500mm precipitation annually
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
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])
Cf - Warm temperate climate, wet all year Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
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)

Latitude/Altitude Ranges

Top of page
Latitude North (°N)Latitude South (°S)Altitude Lower (m)Altitude Upper (m)
30 30

Means of Movement and Dispersal

Top of page

Natural Dispersal

Seeds of S. cayennensis may be dispersed over short distances by rain and run-off. There is some indications that this species may reproduce and spread locally by vegetative propagation (PIER, 2015).

Vector Transmission

Seeds of this species may become attached to the fur of animals and translocated over short distances into new areas (Weeds of Australia, 2011).

Accidental Introduction

It is believed that the spread of this species in Queensland, Australia is a result of accidental introductions via fodder, hay and contaminated pasture seed (Smith, 2002). Seeds may also be introduced into new areas in garden waste or by attachment of seeds to clothing, vehicles and machinery (Weeds of Australia, 2011).

Intentional Introduction

S. cayennensis was intentionally introduced into a number of countries as an ornamental species. This species produced an attractive blue flower which is appealing to bees and butterflies. Seeds of this species are still readily available for sale on the internet.

Impact Summary

Top of page
CategoryImpact
Economic/livelihood Negative
Environment (generally) Negative
Human health Positive

Environmental Impact

Top of page

Impact on Habitats

S. cayennensis is unpalatable to livestock and in areas with heavy grazing this species may outcompete surrounding species (HEAR, 2013).

Impact on Biodiversity

This species is opportunistic and can readily invade disturbed areas. It can form dense thickets which may outcompete or smother native plant species (PIER, 2015). In Florida this species is regarded as a Category II plant, a species which has increased in abundance but has not yet altered plant communities (FLEPPC, 2009).

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Highly adaptable to different environments
  • Pioneering in disturbed areas
  • Tolerant of shade
Impact outcomes
  • Reduced native biodiversity
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
  • Hybridization
Likelihood of entry/control
  • Highly likely to be transported internationally deliberately
  • Difficult to identify/detect in the field

Uses

Top of page

Economic Value

There is no information available on the economic value of S. cayennensis. As an ornamental this species is sold in the nurseries and via the internet and therefore has some economic value.

Social Benefit

In Latin America, S. cayennensis is utilised in traditional medicine to treat symptoms of malaria, treat dysentery and liver disorders, to relieve fevers and to act as a sedative (Taylor, 2012). The plant contains flavonoids, terpenes, phenols and steroids and has been found to have anti-inflammatory and anti-malarial properties (Okoye et al., 2014).

Similarities to Other Species/Conditions

Top of page

Others species within the genus Stachytarpheta closely resemble S. cayennensis. These include S. jamaicensis, S. australis and S. mutabilis. The colour of the flower is often used to differentiate between the species. The flowers of S. jamaicensis are light blue or mauve, S. australis has light blue or white flowers and the stem and lower face of leaves are pubescent and S. mutabilis is characterized by having larger pink or red flowers with a hairy stem.

Hybridization between the closely related species S. cayennensis and S. jamaicensis may occur. The hybrids more closely resemble S. jamaicensis, but the corollas are darker in colour than typical in S. jamaicensis. The habit is more erect, and the leaves are usually more ovate, darker green and with more divergent teeth similar to S. cayennensis (Wagner et al., 1999). S. cayennensis may also hybridize with S. mutabilis. A number of hybrids have been found to have naturalized in Queensland (Weeds of Australia, 2011).

S. cayennensis is also similar in appearance to Verbena litoralis and V. officinalis however these have four stamens instead of two with smaller flowers which are less than 4 mm across (Weeds of Australia, 2011).

Prevention and Control

Top of page

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

SPS Measures

In Australia, S. cayennensis is regarded as an environmental weed and regulations are in place in a number of territories to prevent its spread. In New South Wales this species is restricted, meaning that it cannot be sold or distributed within the territory. In the Northern Territroy this species has been declared a noxious weed. This means that the spread of this species must be controlled and that introductions are prohibited (Weeds of Australia, 2012).

S.cayennensis is included in a list of the 33 most invasive species of the South Pacific (Blanfort et al., 2008).

Control

Physical/Mechanical Control

Manual removal of seedlings by hand can be effective for small populations, ensuring the large roots are also removed. S. cayennensis may also be controlled by chipping or cultivation (ploughing, grubbing and hoeing) (Swarbrick, 1997). Planting of local and vigorous pasture plants, such as legumes, may compete with S. cayennensis and prevent re-establishment.

Biological Control

No biological control agents have been released for S. cayennensis, however possible agents are discussed by Waterhouse and Norris (1987). The potential for biological control of the closely related species S. jamaicensis is discussed in detail by Cock et al. (1985).

Chemical Control

It has been suggested that S. cayennensis is sensitive to foliar application of 2,4-D or MCPA (Motooka et al., 2003). It is however, less sensitive to other hormone type herbicides, although drizzle application of triclopyr in water have been found to be effective in trials in Palau (Motooka et al., 2003). Some control using glyphosate has been recorded. The best control of S. cayennensis can be achieved during the summer months when plants are actively growing (Weeds of Australia, 2011).

IPM

For large areas of S. cayennensis it is recommended that plants are mechanically removed and treated with herbicides. The best time to cut plants is before flowering. It is necessary to follow up and retreat areas with herbicides to provide effective control (Weeds of Australia, 2011).

References

Top of page

Blanfort V; Desmoulins F; Bourgeois TLe; Guiglion R, 2008. Plantes envahissantes et à conflit d'intérêt des pâturages de Nouvelle-Calédonie ([English title not available]). Nouméa, New Caledonia: Institut Agronomiquenéo-Calédonien Editeur, 206 pp.

Carnevali G; Tapia-Muñoz JL; Duno Stefano Rde; Ramírez Morillo, 2010. [English title not available]. (Flora ilustrada de la Peninsula Yucatán: listado florístico.) . Mérida, Mexico: Centro de Investigación Científica de Yucatán, 326 pp.

Chong K; Hugh TW; Corlett RT, 2009. A checklist of the total vascular plant flora of Singapore: native, naturalised and cultivated species., Singapore: Raffles Museum of Biodiversity Research, National University of Singapore, 273 pp.

Cock MJW (ed.), 1985. A review of biological control of pests in the Commonwealth Caribbean and Bermuda up to 1982. Farnham Royal, United Kingdom; Commonwealth Agricultural Bureaux, xii + 218 pp.

Comité français l'Union Internationale pour Conservation Nature France de la de la en, 2013. [English title not available]. (Les espéces envahissantes en outre-mer.) . http://www.especes-envahissantes-outremer.fr/autoComplete/index.php

Cowan CP, 1983. [English title not available]. (Flora de Tabasco. Listados floríst.) México, 1:123 pp.

Davidse G; Sousa Sánchez M; Knapp S; Chiang Cabrera F, 2012. Rubiaceae a Verbenaceae. Flora Mesoamericana, 4:1-533.

Department of Agriculture; fisheries and forestry biosecurity Australia (DAFF), 2014. Snakeweed, Stachytarpheta spp. https://www.daf.qld.gov.au/__data/assets/pdf_file/0005/54392/IPA-Snakeweed-PP52.pdf

Dodson CH; Gentry AH, 1978. Flora of the Rio Palenque Science Center, Los Rios, Ecuador. Selbyana, 4:xxx + 628 pp.

Florida Exotic Pest Plant Council, 2013. Florida Exotic Pest Plant Council's 2013 list of invasive plant species. Florida, USA: Florida Exotic Pest Plant Council. http://www.fleppc.org/list/2013/FLEPPCPlantList2013-PRINTABLEwithlinkstoCAIPpages.pdf

Forzza R, 2010. List of species of the Flora of Brazil (Lista de espécies Flora do Brasil). http://floradobrasil.jbrj.gov.br/2012/

Fosberg F; Sachet M, 1969. Wake Island vegetation and flora, 1961-1963. Atoll Research Bulletin No. 123. Washington, USA: Smithsonian Institution, 15 pp.

Fosberg F; Sachet MH, 1962. Vascular plants recorded from Jaluit Atoll. Atoll Research Bulletin No. 92. Washington, USA: Pacific Science Board, National Academy of Sciences, 29 pp.

Fosberg FR, 1990. A review of the natural history of the Marshall Islands. Atoll Research Bulletin No. 330. Washington, USA: Smithsonian Institution, 100 pp.

Fosberg FR; Sachet M-H; Oliver R, 1979. A geographical checklist of the Micronesian Dicotyledonae. Micronesica, 15:1-295.

Fosberg FR; Stoddart DR, 1994. Flora of the Phoenix Islands, central Pacific. Atoll Research Bulletin, 393:60 pp.

Foster RC, 1958. A catalogue of the ferns and flowering plants of Bolivia (Contributions of the Gray Herbarium no. 184), 1-223.

Funk V; Hollowell T; Berry P; Kelloff C; Alexander SN, 2007. Checklist of the plants of the Guiana Shield (Venezuela: Amazonas, Bolivar, Delta Amacuro; Guyana, Surinam, French Guiana). Contributions from the United States National Herbarium, 584 pp.

Gargominy O; Bouchet P; Pascal M; Jaffre T; Tourneu JC, 1996. [English title not available]. (Consequences des introductions d'especes animals et vegetales sur la biodiversite en Nouvelle-Caledonie.) Rev. Ecol. (Terre Vie), 51:375-401.

Gibson DN, 1970. Verbenaceae. Flora of Guatemala - Part IX, Numbers 1 and 2. Fieldiana, Botany, 24(9/1-2):167-236.

Gilman EF, 2007. Stachytarpheta jamaicensis blue porterweed. Florida, USA: University of Florida. http://edis.ifas.ufl.edu/pdffiles/FP/FP55900.pdf

Hancock IR; Henderson CP, 1988. Flora of the Solomon Islands. Research Bulletin No. 7. Honiara, Solomon Islands: Dodo Creek Research Station.

HEAR, 2012. Alien species in Hawaii. Hawaii Ecosystems at Risk. Honolulu, USA: University of Hawaii. http://www.hear.org/AlienSpeciesInHawaii/index.html

Hokche O; Berry PE; Huber O, 2008. Nuevo Catálogo de la Flora Vascular de Venezuela (New catalogue of the vascular flora of Venezuela). Caracas, Venezuela: Fundación Instituto Botánico de Venezuela, 860 pp.

Holm LG; Pancho JV; Herberger JP; Plucknett DL, 1979. A geographical atlas of world weeds. New York, USA: John Wiley and Sons, 391 pp.

Idárraga-Piedrahita A; Ortiz RDC; Callejas Posada R; Merello M; (eds), 2011. . Medellín, Colombia: Universidad de Antioquia.

Jørgensen PM; Nee MH; Beck (eds) SG, 2014. [English title not available]. (Catalogo de las plantas vasculares de Bolivia.) Monographs in systematic botany from the Missouri Botanical Garden. St Louis, Missouri, USA: Missouri Botanical Garden Press.

Lamberson JO, 1982. A guide to terrestrial plants of Enewetak Atoll. Honolulu, Hawaii, USA: Pacific Science Information Center, Bernice P. Bishop Museum, 73 pp.

Lavergne C, 2006. List des especes exotiques envahissantes a la Reunion [List of exotic invasive species on Reunion.]. Pacific Island Ecosystems at Risk (PIER). http://www.hear.org/pier/references/pierref000519.htm

Lawesson JE; Adsersen H; Bentley P, 1987. An updated and annotated check list of the vascular plants of the Galapagos Islands, 16. Aarhus, Denmark: Aarhus University Press, 74 pp.

MacKee HS, 1994. Catalogue of introduced and cultivated plants in New Caledonia. (Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie.) Paris, France: Muséum National d'Histoire Naturelle, unpaginated.

Meyer JY, 2007. Rapport de mission sur l'Ile d'Uvea (Wallis & Futuna) du 6 au 17 Novembre 2007: Inventaire preliminaire de la flore vasculaire secondaire ([English title not available]). Papeete, Tahiti: Ministère de l'Education, l'Enseignement Supérieur et la Recherche, 39 pp. http://www.li-an.fr/jyves/Meyer_2007_Rapport_Plantes_Introduites_Wallis.pdf

Missouri Botanical Garden, 2014. Tropicos database. St. Louis, Missouri, USA: Missouri Botanical Garden. http://www.tropicos.org/

Mito T; Uesugi T, 2004. Invasive alien species in Japan: the status quo and the new regulation for prevention of their adverse effects. Global Environmental Research, 8(2):171-191.

Motooka P; Castro L; Nelson D; Nagai G; Ching L, 2003. Weeds of Hawaii's Pastures and Natural Areas; an identification and management guide. Manoa, Hawaii, USA: College of Tropical Agriculture and Human Resources, University of Hawaii.

Munir AA, 1992. A taxonomic revision of the genus Stachytarpheta (Verbenaceae) in Australia. Journal of the Adelaide Botanic Gardens, 14(2):133-168.

Nelson C; Proctor GR, 1994. Vascular plants of the Caribbean Swan Islands of Honduras. Brenesia, No. 41/42:73-80.

Okoye TC; Akah PA; Ezike AC; Uzor PF; Odoh UE; Igboeme SO; Onwuka UB; Okafor SN, 2014. Immunomodulatory effects of Stachytarpheta cayennensis leaf extract and its synergistic effect with artesunate. BMC Complementary and Alternative Medicine, 14(376):(5 October 2014). http://www.biomedcentral.com/content/pdf/1472-6882-14-376.pdf

PIER, 2015. Pacific Islands Ecosystems at Risk. Honolulu, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html

Pool A; Rueda RM, 2001. Verbenaceae. (Verbenaceae.) In: Flora de Nicaragua, 85(3) [ed. by Stevens, W. D. \Ulloa, C. \Pool, A. \Montiel, O. M.]. St Louis, Missouri, USA: Missouri Botanical Garden Press, 2497-2525.

Ragone D; Lorence DH, 2003. Botanical and Ethnobotanical Inventories of the National Park of American Samoa. Hawaii, USA: Pacific Cooperative Studies Unit, Department of Botany, University of Hawaii, 91 pp.

Renner SS; Balslev H; Holm-Nielsen LB, 1990. Flowering plants of Amazonian Ecuador - a checklist (AUU reports). Aarhus, Denmark: Aarhus University Press, 241 pp.

Robertson SA; Fosberg FR, 1983. List of plants collected on Coetivy Island, Seychelles. In: Floristics and ecology of Western Indian Ocean islands. List of plants collected on Coetivy Island, Seychelles, 273:253 pp. [Floristics and ecology of Western Indian Ocean islands.]

Shine C; Reaser JK; Gutierrez AT, 2003. Invasive alien species in the Austral-Pacific Region: National Reports & Directory of Resources.

Smith NM, 2002. Weeds of the wet/dry tropics of Australia - a field guide., Australia: Environment Centre NT, Inc, 112 pp.

Sousa Sánchez M; Cabrera Cano EF, 1983. Flora de Quintana Roo. Listados Florísticos de México. 1-100.

Space JC; Flynn T, 2000. Observations on invasive plant species in American Samoa. USDA Forest Service, Honolulu, 51.

Space JC; Flynn T, 2000. Report to the Government of Niue on invasive plant species of environmental concern. USDA Forest Service, Honolulu, 34.

Space JC; Flynn T, 2002. Report to the Government of Samoa on invasive plant species of environmental concern. Hawaii, USA: USDA Forest Service, Institute of Pacific Islands Forestry, 80 pp.

Space JC; Imada CT, 2004. Report to the Republic of Kiribati on invasive plant species on the islands of Tarawa, Abemama, Butaritari and Maiana. Honolulu, Hawaii, USA: USDA Forest Service and Bishop Museum, 103 pp.

Space JC; Lorence DH; LaRosa AM, 2009. Report to the Republic of Palau: 2008 update on invasive plant species. Hawaii, USA: USDA Forest Service, Institute of Pacific Islands Forestry, 233 pp.

Space JC; Waterhouse BM; Miles JE; Tiobech J; Rengulbai K, 2003. Report to the Republic of Palau on invasive plant species of environmental concern. Honolulu, USA: USDA Forest Service.

Swarbrick JT, 1997. Weeds of the Pacific Islands. Technical paper No. 209. Noumea, New Caledonia: South Pacific Commission.

Sykes WR, 1970. Contributions to the flora of Niue. New Zealand Department of Scientific and Industrial Research Bulletin 200. p. 238.

Sykes WR, 1970. Contributions to the flora of Niue. New Zealand Department. Sci. Indust. Res. Bull. 200: 1-321.

Taylor L, 2012. Raintree, tropical plant database. Milam County, Texas, USA. http://www.rain-tree.com/

Thaman RR; Fosberg FR; Manner HI; Hassall DC, 1994. The flora of Nauru. Atoll Research Bulletin, 392:1-223.

The Plant List, 2013. The Plant List: a working list of all plant species. Version 1.1. London, UK: Royal Botanic Gardens, Kew. http://www.theplantlist.org

Topp JMW, 1988. An annotated check list of the flora of Diego Garcia, British Ocean Territory. Atoll Research Bulletin No. 313.

Troncoso NS, 1979. Verbenaceae. (Verbenaceae.) In: Flora Ilustrada de Entre Rios, 5 [ed. by Burkart, A. E.]. Buenos Aires, Argentina: Instituto Nacional de Tecnología Agropecuaria, 229-294.

USDA-ARS, 2015. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

Vargas CC, 1943. La flora de la región descubierta por la expedición de "The Vicking Fund". Revista Univ. (Cuzco), 84:1-19.

Wagner WL; Herbst DR; Sohmer SH, 1999. Manual of the flowering plants of Hawaii. Revised edition. Honolulu, Hawaii, USA: University of Hawaii Press/Bishop Museum Press, 1919 pp.

Waterhouse DF; Norris KR, 1987. Biological control: Pacific prospects. viii + 454pp

Weber E, 2003. Invasive plant species of the world: A reference guide to environmental weeds. Wallingford, UK: CAB International, 548 pp.

Weeds of Australia, 2011. Dark blue snakeweed, Stachytarpheta cayennensis. http://keyserver.lucidcentral.org/weeds/data/03030800-0b07-490a-8d04-0605030c0f01/media/Html/Stachytarpheta_cayennensis

Wester L, 1985. Checklist of the vascular plants of the northern Line Islands. Atoll Research Bulletin, 287:1-38.

Whistler WA, 1996. Botanical survey of Diego Garcia, Chagos Archipelago, British Indian Ocean Territory. Isle Botanica (online), 49 pp. http://www.zianet.com/tedmorris/dg/2005NRMP-Appendixe-botanicalsurvey.pdf

Whistler WA; Atherton J, 1997. Botanical survey of the Huvalu Forest Conservation Area, Niue. Unpublished technical report. 76 pp.

Wiggins IL; Porter DM, 1971. Flora of the Galapagos Islands. Stanford, USA: Stanford University Press.

Wilson SB; Knox GW; Muller KL; Freyre R; Deng ZN, 2009. Seed production and viability of eight porterweed selections grown in northern and southern Florida. HortScience, 44(7):1842-1849. http://hortsci.ashspublications.org/

Yuncker TG, 1959. Plants of Tonga. Bishop Museum Bulletin, 220:343 pp.

Principal Source

Top of page

Draft datasheet under review

Contributors

Top of page

31/03/2015 Original text by:

Erwan Le Nezet, Service d'Etat de l'Agriculture, de la Forêt et de la Pêch, Wallis and Futuna

Distribution Maps

Top of page
You can pan and zoom the map
Save map