Hyptis suaveolens
(pignut)

Pictures

Picture	Title	Caption	Copyright
Title Flowers and leaves Caption Hyptis suaveolens (pignut, stinking Roger or vilayti tulsi); flowers and leaves. Hyderabad, India. September 2008. Copyright ©J.M. Garg/via wikipedia - CC BY-SA 4.0	Flowers and leaves	Hyptis suaveolens (pignut, stinking Roger or vilayti tulsi); flowers and leaves. Hyderabad, India. September 2008.	©J.M. Garg/via wikipedia - CC BY-SA 4.0
Title Flowers and leaves Caption Hyptis suaveolens (pignut, stinking roger or vilayti tulsi); flowers and leaves. Hyderabad, India. September 2008. Copyright ©J.M. Garg/via wikipedia - CC BY-SA 4.0	Flowers and leaves	Hyptis suaveolens (pignut, stinking roger or vilayti tulsi); flowers and leaves. Hyderabad, India. September 2008.	©J.M. Garg/via wikipedia - CC BY-SA 4.0

Identity

Preferred Scientific Name

• Hyptis suaveolens (L.) Poit.

Preferred Common Name

• pignut

Other Scientific Names

• Ballota suaveolens L.
• Bystropogon graveolens Blume
• Bystropogon suaveolens (L.) L'Hér.
• Gnoteris cordata Raf.
• Gnoteris villosa Raf.
• Hyptis congesta Leonard
• Hyptis ebracteata R.Br.
• Hyptis graveolens Schrank
• Hyptis plumieri Poit.
• Marrubium indicum Blanco
• Mesosphaerum suaveolens (L.) Kuntze
• Schaueria graveolens (Blume) Hassk.
• Schaueria suaveolens (L.) Hassk.

International Common Names

• English: bushmint; chan; chao; horehound; mintbush; mintweed; mumutun; spikenard; stinking Roger; wild spikenard
• Spanish: chia grande; hierba de las muelas
• French: chan; gros baume; hyptide perfume; hyptis à odeur
• Portuguese: alfavaca-brava; betônica-brava; chan; hortela do campo; mentrasto do grande

Local Common Names

• Benin: azongbidi; disibu; efintin aja; emugbé; fioho; kukubi; kuwi; tiname tieti; wusakadi; xweflu
• Burkina Faso: fè; gbè; sosso
• China: shan xiang
• Congo Democratic Republic: mvouamvoua; nvonanvona
• Côte d'Ivoire: sésémoro
• Ghana: brong peeah; filingoro
• Guam: mumutun
• Guatemala: chía; chichinguaste; salvia blanca; turturitillo
• India: bhustrena; bhustrna; bilatti tulas; darp tulas; ganga tulasi; jungli tulas; nattapoochedi; sirna tulasi; walayati tulsi
• Indonesia: babadotan; jakut bau
• Malaysia: malbar hutan; pokok kemangi; sělaséh hutan
• Mexico: chana; chia de Colima; chia gorda; confitura; confiturilla; conivaria; la-pil; xóotle'xnuuk
• Micronesia, Federated states of: lamar nuteth; lekenek; mengit; nekenek; nokonok
• Nigeria: jogbo; koulouvi; koutoubi
• Philippines: kablíng kabáyo
• Senegal: brégé; gumgûné; kuyhuye; ngungun
• Tanzania: kifumbasi
• Thailand: kaaraa; maeng lak khaa
• Togo: awussakadi; mugbé
• Vietnam: esthowm; tiastoodaji

Summary of Invasiveness

Hyptis suaveolens is an annual herb that grows in disturbed habitats. It is a prolific seed producer and in dense infestations can yield up to 3000 seeds/m², forming persistent propagule banks within a short period (Sharma et al., 2009). Thanks to its capability to stick to fur and cloth it disperses to undisturbed areas, where it can remain dormant for extended periods, until vegetation is cleared (Parsons and Cuthbertson, 2001). H. suaveolens forms dense thickets and has the ability to shade out and displace native vegetation, especially in grazed or disturbed areas, but also in riparian vegetation and on floodplains (Queensland Government, 2012).

H. suaveolens is considered invasive in Hawaii, Guam, Niue, Papua New Guinea, the Philippines, Singapore, and Taiwan (PIER, 2016). GBIF (2016) lists it as invasive in parts of Africa and South Asia. It has been categorised as one of the most serious invaders in the highlands of West-Central India (Sharma et al., 2009). In Australia, it is regarded as an environmental weed in northern Queensland and northern Western Australia. In the Northern Territory, it is listed as a noxious weed (Queensland Government, 2012). On PIER (2016), a risk assessment prepared for Australia gives it a score of 19 (Reject).

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Lamiales
•                         Family: Lamiaceae
•                             Genus: Hyptis
•                                 Species: Hyptis suaveolens

Notes on Taxonomy and Nomenclature

Hyptis is a genus of the mint family (Lamiaceae) that comprises about 300 species (The Plant List, 2013) and is indigenous in the American tropics and subtropics (Handayani, 2003). The name of this genus stems from the Greek huptios (turned back), referring to the abrupt turning down of the lobes of the lower lip of the corolla (Parsons and Cuthbertson, 2001).

Hyptis suaveolens presents high levels of genetic polymorphism and plasticity in morphological and physiological responses (Wulff, 1987), a quality that allows it to adapt to environmental alterations and that results in interpopulational and intrapopulational variability of its chemical components (Barbosa et al., 2013), as well as flower and seed polymorphism (Gadidasu et al., 2011; Wulf, 1973). However, these differences are so minimal that a taxonomic status does not need to be assigned to variants (Gadidasu et al., 2011).

The species was first described in 1806 by French botanist Pierre-Antoine Poiteau. The Latin epithet suaveolens means “sweet scented,” referring to this species’ odour (Hyde et al., 2016).

Description

Adapted from the Queensland Government (2012):

H. suaveolens is an erect, annual or short-lived perennial herbaceous plant usually growing 1-1.5 m tall, but occasionally reaching up to 3 m in height. The branching stems are green or reddish-green in colour and square in cross-section when young. On the upper parts of the plant the stems are about 5 mm thick and somewhat hairy. The lower parts are thicker and become slightly woody towards the base.

Leaves (2-10 cm long and 1-7 cm wide) are oppositely arranged and borne on petioles that are 5-40 mm long. Leaves are ovate (egg-shaped), elliptic (oval), or slightly cordate (heart-shaped). Margins are shallowly toothed and pubescent.

Flowers are small (5-7 mm long), pinkish, bluish-purple or lavender in colour and arranged at the axils in 1-5 flowered clusters. Pedicels are 1-5 mm long. Flowers are tubular in appearance with two 'lips' (two-lipped or bi-labiate). The upper lip is divided into two lobes and the lower lip divided into three lobes. The central lobe is saccate (having an inflated appearance). These flowers are surrounded by a green tubular structure that is formed from the five fused sepals (i.e. a calyx tube). It has five lobes, each being topped with a short bristle (about 5 mm long), and turns brown in colour after the flower dies. The fruit is a schizocarp (lobed structure) that divides into two 'seeds' (mericarps). These 'seeds' (3-4 mm long and 2.5-3 mm in wide) are dark brown to black in colour with whitish markings at one end. They are flattened, shield-shaped and slightly rough in texture.

Plant Type

Distribution

This species originates from the Neotropics, from Central America and the West Indies south to about the tropic of Capricorn. It has been introduced to the tropics and subtropics of the world (including some Pacific Islands), where it has become widely naturalized. Padalia et al. (2015) modelled the potential distribution of H. suaveolens and suggest that areas between 34° 02′ north and 28° 18′ south latitudes in the tropics are climatically suitable for this species, with West and Central Africa, tropical southeast Asia and northern Australia at high risk of invasion.

Distribution Table

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.

History of Introduction and Spread

Although the exact year of its introduction is not known, in Australia, this species was first recorded in 1845 (Cullen et al., 2012). It is spreading in India (Padalia et al., 2014), and was first recorded in Zhejiang, China in 2013 (Xiong et al., 2013).

Habitat

This species is common in wetter tropical regions, but it can also occurs in sub-tropical and semi-arid environments. H. suaveolens is quantitatively unimportant in savannas where human impact is low (Schwarzkopf et al., 2009). It is a weed of roadsides and cultivation, pastures, rangelands, grasslands, open woodlands, riverbanks, floodplains, coastal regions, disturbed sites, and waste areas. In India, it is found along rail tracks and roadsides, in foothills of open forests, forest clearings, and on wasteland particularly on arid and rocky substrates (Raizada, 2006). It occurs at altitudes ranging from 0 to 1600 m (Standley and Steyermark, 1946).

Habitat List

Hosts/Species Affected

This species competes for space and nutrients with groundnuts (Arachis hypogaea) (Parsons and Cuthbertson, 2001). In controlled trials, it has also shown allopathic properties that inhibit the growth of wheat (Triticum aestivum) finger millet (Eleusine coracana) (Poornima et al., 2015), and mung beans (Vigna radiata) (Maiti et al., 2015).

Host Plants and Other Plants Affected

Biology and Ecology

Genetics

The chromosome number reported for H. suaveolens is 2n = 24, 28, 30, 23 (Handayani, 2003).

Reproductive Biology

The flowers of this species offer nectar and pollen to foraging visitors (Aluri, 1990). Insects, specially bees (Trigona spp., Ceratina spp., and Pithitis spp.) and occasionally butterflies, pollinate it. Anthers are explosively liberated from the corolla lower lip upon visitation of pollinators, which in turn results in self- and cross-pollination (Aluri, 1990). H. suaveolens reproduces both by seed (Queensland Government, 2012) and vegetatively (Rivington, 1838; Sharma et al., 2007). Seed production is very high (Raizada, 2006).

Physiology and Phenology

Vegetative growth in H. suaveolens begins either from rootstocks or seeds. Growth is rapid, and flowering can start at an early age of 2-3 months (Raizada, 2006). Seeds are protected in spined burrs within small nutlets. Seeds can germinate in a wide range of temperatures (10-40°C), but optimum temperature for growth is 25-30°C. The dimorphic seeds, combined with the wide range of germination temperatures, means that germination occurs throughout the year (Raizada, 2006).

Longevity

H. suaveolens is an annual species. However, under favourable conditions, it may overwinter and support new growth from the base of the plant as a short-lived perennial (Cullen et al., 2012). Seeds can remain dormant for many years in the soil until suitable germination conditions arise (PIER, 2016).

Activity Patterns

This species flowers from late summer through until late winter. Investigations focusing on flowering of this species concluded it is a short day plant, with critical photoperiod of approximately 13 hours (Barbosa et al., 2013).

Population Size and Structure

This species forms dense stands (Queensland Government, 2012).

Nutrition

Although the nutritional requirements for H. suaveolens have not been studied, this species has been successfully grown by Schwarzkopf et al. (2009) on soils with relatively acidic clay-sandy textured with high aluminum availability. It is likely, however, this this species thrives on other soils as well, particularly those where maize, groundnuts, wheat, and millet can be cultivated.

Associations

The green lynx spider (Peucetia viridans) has evolved a camouflage that resembles the colour, veins, and shape of the leaves and floral bracts of Hyptis suaveolens (Aluri, 1990). This spider occupies the flowering cymes of H. suaveolens and preys intensively upon its bee pollinators and reduces them to half of their usual pollinating frequency, thereby reducing self- or cross-pollination and limiting natural fruiting and seeding (Aluri, 1990). It is also likely that the spider has developed mimicry to protect itself against predators (Aluri, 1990).

Environmental Requirements

Long illumination periods and temperatures between 20 and 45°C promote full germination of this species (Wulff and Medina, 1971). This species does not tolerate water logging and has little tolerance to drought (Wulff, 1987). According to Rivington (1838), H. suaveolens prefers light and dry soil.

Climate

Latitude/Altitude Ranges

Air Temperature

Soil Tolerances

Soil drainage

• free

Soil texture

• light

Notes on Natural Enemies

Aluri (1990) has reported an unidentified Katydid bush cricket resembling the leaves of H. suaveolens and eating its floral parts (except for the calyx) thus adding handicap for the reproductory success of the plant. Cullen et al. (2012) noted that in spite of its long presence in Australia, only six herbivores feed on this species (most likely because of its toxic components). Moreover, observations on herbivore susceptibility of this species by Queiroz-Voltan et al. (1995) suggest that this plant’s susceptibility to predators varies not only as a result of toxicity variability (which is correlated to environmental conditions), but also to growth stage. The raspberry pyrausta moth (Pyrausta insignatalis), for example, is probably well adapted to the plant and appears to be resistent to H. suaveolens terpenes (Queiroz-Voltan et al., 1995).

Means of Movement and Dispersal

Natural Dispersal

This species is dispersed by water (Cullen et al., 2012).

Vector Transmission (Biotic)

The seeds of H. suaveolens remain in the bristly fruit, which easily attaches to fur and clothing (Cullen et al., 2012). The mucilaginous coating of the seeds, when wet, adhere to potential vectors as well (Merril, 1981).

Accidental Introduction

This species is spread as a contaminant of hay, as well as in mud on animal hooves, machinery, and vehicles (Raizada, 2006; Cullen et al., 2012).

Pathway Causes

Pathway Vectors

Economic Impact

Although the economic losses due to the invasion of H. suaveolens in agricultural fields have not been assessed, it is possible to state that substantial resources go annually to controlling this weed (Schwarzkopf et al., 2009). Wiersema and León (1999) consider this species an economically important weed due not only to its potential as a seed contaminant, but also from the positive impact because of its medicinal value. In northwest India, the absence of several species of economic importance to local people in areas heavily invaded by S. suaveolens may pose socioeconomic problems for local people in periurban ecosystems (Sharma et al., 2017).

Environmental Impact

Because of its unpalatability to livestock, H. suaveolens has the ability to dominate improved and native pastures, especially when they are overgrazed. Hence, this species can significantly reduce the carrying capacity and/or productivity of pastures (Queensland Government, 2012). Sharma et al. (2017) investigated the impact of H. suaveolens on the natural vegetation in periurban ecosystems of Chardigarh, northwestern India, and found that species numbers declined by 46-52% in heavily invaded areas. Several economically important species were absent from invaded areas, but present in areas without H. suaveolens. In Pakhal Wildlife Sanctuary, Andhra Pradesh, India, H. suaveolens has become widespread, occupying grazing areas of wild animals and preventing the native ground flora from growing (Murthy et al., 2007). It may also enhance the risk of forest fire in the dry seasons (Murthy et al., 2007).

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• 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)
• Fast growing
• Has high reproductive potential
• Gregarious
• Has propagules that can remain viable for more than one year
• Reproduces asexually
• Has high genetic variability

• Monoculture formation
• Negatively impacts agriculture
• Transportation disruption

• Allelopathic
• Competition - shading
• Rapid growth

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant
• Difficult/costly to control

Uses

In spite of its detrimental impacts, H. suaveolens has been regarded as a beneficial plant due to its fungicidal activity (Cowie, 2012), bacterial growth suppression, and weed seed germination inhibition (Schwarzkopf et al., 2009).

Economic Value

This species has a potential economic value for small farmers. In Southern Benin, both aqueous extracts and living specimens of H. suaveolens have been proven to significantly reduce population densities of stemborers (Sesamia calamistis (Lepidoptera: Noctuidae)), a problematic pest that constrains maize production of resource-poor farmers (Adda et al., 2011). In several parts of Asia, peasants use this species to protect livestock from vermin (Handayani, 2003). The leaves can be used as a bedbug repellent.

Social Benefit

In many regions of Central America, the seeds of H. suaveolens are made into a drink which is prepared in the same fashion as chia (Salvia hispanica) (Standley and Williams, 1973). In Mexico, this species is also used in the treatment of cataracts by the Raramuri of Chihuahua (Irigoyen-Rascón, 2015), and as fodder for poultry by the Mayas of Yucatán (Flores and Bautista, 2012). Moreover, antimicrobial, antifungal, hypoglycemic, antiinflamatory, and antioxidant activity has been found in this species (Rojas Chavez and Vibrans, 2011).

Outside of its native range, this species has also become an important useful species with applications similar to those of the Neotropics. In Benin, this species is used externally in combination with other medicinal plants to treat jaundice, hyperthermia, haemorrhoids, breast abscess, oedemas and perianal candidiasis (Adjanohoun et al., 1989), and in the treatment of sexually transmitted diseases (Towns and Andel, 2014). In Nigeria, this plant is used in the treatment of cougha, fever, and anemia (Odugbemi, 2008).

Handayani (2003) has listed some of the uses people give to this species in Asia: In several parts of the continent, leaves and stems are employed in the treatment of cuts, wounds, eczema, bruises, and other skin diseases. In the Philippines, leaves are used externally to treat rheumatism, and internally as an antispasmodic. Leaves and roots are used as as insecticide and against rheumatism, respectively. In Papua New Guinea leaves are used internally to treat catarrh and fever. In Indonesia, this species is used as a galactagogue. In Thailand, pounded leaves and branches are used as a lice repellent for chickens. The whole plant is occasionally used as fodder for livestock (Handayani, 2003).

Other uses include potential as a monitor of trace metals (Pb, Fe, Zn, Cu, and Cr) in soil from automobiles (Usman, 2013).

Environmental Services

Mandal et al. (2007) found that the seeds of H. suaveolens are an absorbent capable of removing up to 64% of arsenic as arsenate from water. For this purpose, seeds preteated with boiling water low in pH (3.5-4.5) have proven cost effective and might be used for large-scale water treatment systems (Mandal et al., 2007).

Uses List

Environmental

• Soil improvement

Materials

• Pesticide

Medicinal, pharmaceutical

• Traditional/folklore

Similarities to Other Species/Conditions

According to the Queensland Government (2012), H. suaveolens is relatively similar to other members of the mint family such as Leonotis nepetifolia, and Marrubium vulgare, and particularly, a congener species Hyptis capitata. H. suaveolens can be distinguished from all the other species by its pinkish, bluish-purple or lavender coloured flowers that are borne in loose few-flowered clusters in the axils. H. capitata, on the other hand, has white flowers that are borne in small dense globular clusters (15-25 mm across) at the top of peduncles; while L. nepetifolia has orange flowers that are borne in large stalkless (i.e. sessile) globular clusters (50-60 mm across) in the upper axils. M. vulgare, just as H. capitata, has white flowers born in the axils, but these flowers have a persistent green calyx that turns brown with time. Moreover, the leaves of M. vulgare are crinkled in appearance and have bluntly toothed margins (Queensland Government, 2012).

Prevention and Control

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.

Schwarzkopf et al. (2009) state that where the species has become prevalent, it is not only difficult but also expensive to control. Control measures (such as chemical and mechanical) where it occurs as an agricultural weed are limited due to the overlapping growing season of the weed and crops.

Physical/Mechanical Control

Evidence from Australia suggests that grazing in association with the use of perennial climbing legumes (such as calopo, Calopogonium mucunoides) provides effective control of H. suaveolens in pasture areas (Parsons and Cuthbertson, 2001). In contrast, mowing or slashing provides only temporary relief (Parsons and Cuthbertson, 2001).

Schwarzkopf et al. (2009) state that trying to control this species by means of ploughing before crop planting has a positive effect on the population growth rate since ploughing reduces germination but enhances seed production. Therefore, ploughing would be recommended only if seed production is controlled (i.e. removal of the weed before seed set) (Schwarzkpf et al., 2009). In this respect, Biosecurity Queensland (2014) recommends pulling isolated individuals and small infestations of H. suaveolens, hand pulling them prior to seeding when the soil is wet, and collecting heads into bags for disposal. Parsons and Cuthbertson (2001) recommend grubbing and burning plants prior to seeding, paying attention to cut well down the root. Moreover, control of cropping areas should involve rotations that include tall-growing crops to shade out this species (Parsons and Cuthbertson, 2001).

Further, Schwarzkopf et al. (2009) state that harvesting crops from mid to end rainy season may reduce seed set of H. suaveolens and would therefore enhance the control of this species, since no seeds are added to the seed bank, which is depleted yearly. Also no till practices would enhance control of the weed (Schwarzkopf et al., 2009).

Biological Control

Efforts to control H. suaveolens with biological control agents in Australia commenced in 1980, and yielded a promising rust disease from Mexico (Parsons and Cuthbertson, 2001). However, Cowie (2012) states that these attempts have been unsuccessful so far. In spite of the presumably high number of predators and pathogens of this species and their potential in reducing the density of H. suaveolens, this weed is likely to remain a problem (Cowie, 2012).

Pandey and Pandey (2009) collected strains of Phoma herbarum from diseased H. suaveolens in India, and suggest that this fungus has potential as a mycoherbicide against the weed.

Chemical Control

According to Parsons and Cuthbertson (2001), the use of chemicals provides the most effective method to control H. suaveolens. These authors recommend using an overall spray of amine or ester 2,4-D and spot spraying where applicable (other herbicides such as dicamba, clopyralid and picloram based mixtures are also effective, but more expensive). Moreover, all spraying should be done before plants flower, particularly with an early application followed by a secondary one to kill late-germinated seedlings (Parsons and Cuthbertson, 2001).

References

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Distribution References

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Murthy E N, Raju V S, Reddy C S, 2007. Occurrence of exotic Hyptis suaveolens. Current Science. 93 (9), 1203. http://www.ias.ac.in/currsci

PIER, 2016. Pacific Islands Ecosystems at Risk. In: Pacific Islands Ecosystems at Risk. Honolulu, Hawaii, USA: HEAR, University of Hawaii. http://www.hear.org/pier/index.html

Purnima Raizada, 2006. Ecological and vegetative characteristics of a potent invader, Hyptis suaveolens Poit. from India. Lyonia. 11 (2), 115-120. http://www.lyonia.org/viewArticle.php?articleID=499

Queensland Government, 2012. Weeds of Australia. Biosecurity Queensland Edition., Australia: The University of Queensland. http://keyserver.lucidcentral.org/weeds/

Sharma G P, Purnima Raizada, Raghubanshi A S, 2009. Hyptis suaveolens: an emerging invader of Vindhyan plateau, India. Weed Biology and Management. 9 (3), 185-191. http://www.blackwell-synergy.com/loi/wbm DOI:10.1111/j.1445-6664.2009.00338.x

Witt A, Luke Q, 2017. Guide to the naturalized and invasive plants of Eastern Africa. [ed. by Witt A, Luke Q]. Wallingford, UK: CABI. vi + 601 pp. http://www.cabi.org/cabebooks/ebook/20173158959 DOI:10.1079/9781786392145.0000

Xiong XianHua, Wu QingLing, Chen XianXing, Hu RenYong, Wu YuNan, Ding BingYang, 2013. Two genera and five species newly recorded in Zhejiang Province, China. Journal of Zhejiang University (Agriculture and Life Sciences). 39 (6), 695-698. http://www.journals.zju.edu.cn/agr

Links to Websites

Contributors

05/05/2016, Original Text by:

Dr Diana Quiroz, Naturalis Biodiversity Center, Netherlands

Distribution Maps