Croton argenteus
(silver July croton)

Identity

Preferred Scientific Name

• Croton argenteus L.

Preferred Common Name

• silver July croton

Other Scientific Names

• Cicca argentea (L.) Kuntze
• Cicca montevidensis (Klotzsch ex Baill.) Kuntze
• Cieca argentea (L.) Kuntze
• Cieca montevidensis (Klotzsch ex Baill.) Kuntze
• Croton atwoodianus F.Seym.
• Croton integer (Chodat) Radcl.-Sm. and Govaerts
• Heterochlamys quinquenervia Turcz.
• Heterochlamys quinquinervis Turcz.
• Julocroton argenteus (L.) Didr.
• Julocroton argenteus var. managuensis Ram.Goyena
• Julocroton camporum Chodat and Hassl.
• Julocroton elaeagnoides S.Moore
• Julocroton integer Chodat
• Julocroton integer f. parvifolia Chodat and Hassl.
• Julocroton linearifolius (Chodat and Hassl.) Croizat
• Julocroton montevidensis Klotzsch ex Baill.
• Julocroton montevidensis var. elata Chodat and Hassl.
• Julocroton montevidensis var. glabra Herter
• Julocroton montevidensis var. guatemalensis Müll.Arg.
• Julocroton montevidensis var. lanceolatus Müll.Arg.
• Julocroton montevidensis var. linearifolius Chodat and Hassl.
• Julocroton montevidensis var. pilosus Müll.Arg
• Julocroton montevidensis var. virgatus Chodat and Hassl.
• Julocroton pilosus (Müll.Arg.) Herter
• Julocroton quinquenervius Baill.

International Common Names

• Spanish: croto; croton
• Portuguese: velame-da-lagoa

Local Common Names

• Cuba: yulocroton

Summary of Invasiveness

C. argenteus is an herbaceous weed of open sunny sites, pastures, and agricultural lands. It is also a common weed in rice plantations (González, 2000). Because this species grows in seasonally waterlogged areas, its seeds are often dispersed as a contaminant in dried and wet mud (Standley and Steyermark, 1946). Currently, it is listed as invasive only in Cuba, but it is a common weed in dry and wet fields in areas within and outside its native distribution range (Oviedo Prieto et al., 2012; USDA-NRCS, 2015).

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Euphorbiales
•                         Family: Euphorbiaceae
•                             Genus: Croton
•                                 Species: Croton argenteus

Notes on Taxonomy and Nomenclature

The family Euphorbiaceae includes around 218 genera and 6,745 species with Pantropical distribution. Euphorbiaceae species can be recognized by the following traits: the leaves on one branch are often variable in size and/or shape, the secondary veins are often palmate, the margins are toothed, and there are sometimes glands of various kinds. Species are monoecious or dioecious, the flowers are small, the perianth is usually inconspicuous, there are usually three carpels with prominent stigmas, and the fruits have a distinctive and persistent columella, large and often carunculate seeds and explosive dehiscence. Euphorbiaceae species are quite often poisonous (Stevens, 2012). With about 1300 species, Croton is the second largest genus within the family Euphorbiaceae. Croton species are trees, shrubs, and herbs distributed in warm-temperate regions. South America, the West Indies and Mexico are important centres of species diversity for this genus (Webster, 1993; Burger and Huft, 1995).

Description

The following description comes from Burger and Huft (1995):

Annual herbs 0.2-1 m tall, bisexual, leafy stems 0.8-7.5 mm thick, stellate-pubescent with appressed hairs 0.3-0.5 mm diameter or with long rays to 0.9 mm; stipules 4-11 mm long, linear-subulate, simple or divided distally, with hairs to 1.4 mm long. Leaves often closely congested beneath the inflorescences, petioles 3-105 mm long, 0.7-2 mm thick, appressed stellate-pubescent, glands absent at apex; leaf blades 1.8-10(-15) cm long, 1.2-6(-8) cm wide, ovate to ovate-oblong, apex bluntly obtuse to rounded, margin minutely or obscurely denticulate, base obtuse or cuneate to subtruncate, drying chartaceous and pale grayish green beneath, stellate-pubescent with appressed hairs 0.1-0.4 mm diameter, venation palmate with usually 5 major veins from the base. Inflorescences terminal, bisexual, 1-4 cm long, often subtended by small (15 ×12 mm) leaves, congested and resembling a capitulum, bracteoles approximately 3 mm long, subtending solitary flowers, female flowers proximal, pedicels to 5 mm long in fruit, male flowers with pedicels 2 mm long. Male flowers with calyx 1.5-2 mm long, sepal lobes approximately 1 mm long, petals 2-3 mm long, 0.3-0.4 mm wide, glabrous except on the margin; stamens 11, anthers 0.6-0.8 mm long. Female flowers with 5 unequal sepals, 6-8 mm long in fruit, petals absent, disk with 5 unequal lobes, styles distally 4 times bifid. Fruits 5 mm long, borne on pedicels 3-5 mm long, sepals 6-8 mm long and 3.5-6 mm wide, columella 3-4.5 mm long; seeds 3.2-3.8 mm long, 2.4-3 mm wide, 2.2 mm thick, rounded-oblong, caruncle approximately 1.8 mm wide).

Plant Type

Distribution

C. argenteus is native to America from Mexico to Argentina. It is listed as introduced in the United States and Cuba (Oviedo Prieto et al., 2012; USDA-NRCS, 2015).

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.

Risk of Introduction

Considering the invasive potential of some other Croton species and given that C. argenteus is listed as invasive in Cuba (Oviedo Prieto et al., 2012), the risk of introduction of this species beyond its current distribution is therefore moderate to high.

Habitat

C.argenteus grows in open sunny sites in seasonally dry habitats from sea level up to 1200 metres (Standley and Steyermark, 1946). It is a weedy herb often found in gardens, pastures, rice plantations, sugarcane plantations, and wet to dry thickets (Standley and Steyermark, 1946; González, 2000).

Habitat List

Hosts/Species Affected

C. argenteus is a weed of pastures and rice and sugarcane plantations (Standley and Steyermark, 1946; González, 2000; Torres et al., 2010).

Host Plants and Other Plants Affected

Growth Stages

Biology and Ecology

Reproductive Biology

C. argenteus is a monoecious herb. The pollination system of the genus Croton is poorly known, but it is expected to be diverse because entomophily (mainly Hymenoptera, Diptera, and Coleoptera), anemophily, and ambophily have all been documented in this genus (Narbona and Dirzo, 2010).

Physiology and Phenology

C. argenteus is an annual herb. In Central America, during the wet months this plant grows commonly in fields, thickets and disturbed sites but it soon withers after the rains cease. There it usually is associated with Glinus and one or more species of Heliotropium (Standley and Steyermark, 1946).

C. argenteus has been collected with flowers in January-February and May in Costa Rica and in August in Nicaragua (Burger and Huft, 1995).

Environmental Requirements

C. argenteus prefers to grow in wet and dry habitats from sea level to 1200 metres in elevation. It is able to grow in seasonally waterlogged areas and on soils with pH ranging from 6.1 to 7.5 (Standley and Steyermark, 1946; Burger and Huft, 1995).

Climate

Soil Tolerances

Soil drainage

• seasonally waterlogged

Soil reaction

• acid
• neutral

Soil texture

• light
• medium

Means of Movement and Dispersal

C. argenteus spreads by seeds. Seeds are often dispersed as a contaminant in dried and wet mud (Standley and Steyermark, 1946).

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

Currently, C. argenteus is listed as invasive only in Cuba (Oviedo Prieto et al., 2012). However, within and outside its native distribution range, this species grows as a weed impacting agriculture (i.e., rice and sugarcane plantations), pastures, and wet and dry thickets (Standley and Steyermark, 1946; Burger and Huft, 1995). In Cuba, this species occurs extensively across the island principally in the western region, where it is a common weed in ruderal areas, pastures, agricultural lands, and along roadsides (Morón Rodríguez et al., 2006).

Risk and Impact Factors

• Proved invasive outside its 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
• Fast growing

• Negatively impacts agriculture
• Reduced native biodiversity

• Competition - monopolizing resources
• Competition - smothering
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field

Uses

C. argenteus is used in traditional medicine to treat health problems, such as diarrhoea, wounds, gastroduodenal ulcers, inflammations, pain, insect bites, and viral infections (Morón Rodríguez et al., 2006).

Uses List

Medicinal, pharmaceutical

• Traditional/folklore

References

Burger WC, Huft M, 1995. Flora Costaricensis. Family 113, Euphorbiaceae., Fieldiana, 36:1-169

Cordeiro I, Secco R, Carneiro-Torres DS, Lima LR, Caruzo MBR, Berry P, Riina R, Silva OLM, Silva MJ, Sodré RC, 2015. Croton in Lista de Espécies da Flora do Brasil http://floradobrasil.jbrj.gov.br/jabot/floradobrasil/FB35767

González J, 2000. Euphorbiaceae. Manual de Plantas de Costa Rica., Instituto Nacional de Biodiversidad- Museo Nacional de Costa Rica.

Govaerts R, 2015. World Checklist of Euphorbiaceae. http://apps.kew.org/wcsp/

Morón Rodríguez F, Victoria Amador MDC, Morejón Rodríguez Z, Martínez Guerra MJ, López Barreiro M, Fuentes Fiallo V, 2006. Validación preclínica de extractos fluidos de Croton argenteus L., Revista Cubana de Plantas Medicinales, 11(2):1-10

Narbona E, Dirzo R, 2010. A reassessment of the function of floral nectar in Croton suberosus (Euphorbiaceae): a reward for plant defenders and pollinators., American Journal of Botany, 97(4):672-679 http://www.amjbot.org/

Oviedo Prieto R, Herrera Oliver P, Caluff MG, et al. , 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba, 6(Special Issue 1):22-96.

Standley PC, Steyermark JA, 1946. Leguminosae. Flora of Guatemala, Fieldiana Botany, 24(5):1-368

Stevens PF, 2012. Angiosperm Phylogeny Website. http://www.mobot.org/MOBOT/research/APweb/

Torres ZAS, Velázquez MC, Rodríguez YF, 2010. Croton argenteus L.(Euphorbiaceae), nueva especie de arvense en el cultivo de la caña de azúcar (Sacharum officinarum Lin.) en Majibacoa., Fitosanidad, 14(2):121

USDA-NRCS, 2015. The PLANTS Database. http://plants.usda.gov/

Webster GL, 1993. A provisional synopsis of the sections of the genus Croton (Euphorbiaceae)., Taxon, 42:793-823

Distribution References

Cordeiro I, Secco R, Carneiro-Torres DS, Lima LR, Caruzo MBR, Berry P, Riina R, Silva OLM, Silva MJ, Sodré RC, 2015. (Croton in Lista de Espécies da Flora do Brasil)., http://floradobrasil.jbrj.gov.br/jabot/floradobrasil/FB35767

Govaerts R, 2015. World Checklist of Euphorbiaceae., http://apps.kew.org/wcsp/

Oviedo Prieto R, Herrera Oliver P, Caluff M G, et al, 2012. National list of invasive and potentially invasive plants in the Republic of Cuba - 2011. (Lista nacional de especies de plantas invasoras y potencialmente invasoras en la República de Cuba - 2011). Bissea: Boletín sobre Conservación de Plantas del Jardín Botánico Nacional de Cuba. 6 (Special Issue No. 1), 22-96.

USDA-NRCS, 2015. The PLANTS Database. Greensboro, North Carolina, USA: National Plant Data Team. https://plants.sc.egov.usda.gov

Links to Websites

Contributors

03/05/16 Original text by:

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

Distribution Maps