Florida Firespike

Florida Firespike is common in Central Florida gardens and in full winter bloom. Firespike is arguably one of Florida's more attractive invasive species, and it is spreading north. Alternatively described as Odontonema cuspidatum, O. tubiforme, O. tubaeforme (Bertol.) Kuntze, and O. strictum, individuals found in Florida are more than likely the same species, a native of Mexico. Read more about the taxonomy of Firespike below.

Follow Phillip

@majikphil

In its native range Firespike is pollinated by specialized hummingbirds. There are few hummingbirds in Central Florida in winter so butterflies take over. Above, a Giant Swallowtail feeds on Firespike.

Identity

Preferred Scientific Name

Odontonema cuspidatum (Nees) Kuntze

Preferred Common Name

Florida Firespike or Cardinal’s guard

Other Scientific Names

Odontonema strictum Sensu West Indian authors, non (Nees) Kuntze

Thyrsacanthus cuspidatus Nees

Odontonema tubiforme

Odontonema tubaeforme (Bertol.) Kuntze

International Common Names

English: cardinal flower; cardinal’s crest; fire spike; mottled toothedthread; odontonema; red justicia; scarlet firespike; Florida Firespike

Local Common Names

Florida: Florida Firespike

Ecuador: lava botellas

Mexico: coral de jardín; flor de chupa miel; flor de chuparrosa

Paraguay: clavo de fuego

Saint Lucia: firespike

Summary of Invasiveness

O. cuspidatum is a shrub commonly planted as an ornamental for its attractive red tubular flowers. It has escaped from cultivation and can be found naturalized in disturbed areas as well as in relatively unaltered forests (Lorence et al., 1995; Space and Flynn, 2002; Meyer and Lavergne, 2004). O. cuspidatum represents a serious problem due to its ability to invade the understory of native forests. O. cuspidatum is included in the Global Compendium of Weeds (Randall , 2012), and it is also listed as invasive in Hawaii, French Polynesia, Samoa, the Galápagos Islands, and Cuba (Lorence et al., 1995; Meyer and Lavergne, 2004; Oviedo Prieto et al., 2012; PIER, 2014). It is considered as potentially invasive in Puerto Rico (Rojas-Sandoval and Acevedo-Rodríguez, unpublished data).

Notes on Taxonomy and Nomenclature

The family Acanthaceae includes about 221 genera and 4000 species widespread in both New and Old World Tropics (Scotland and Vollesen, 2000; Stevens, 2012). Species within this family are herbs or woody shrubs, lianas and trees. Member of the Acanthaceae may be recognized by their fruit: a few-seeded, explosively dehiscent capsule within which seeds are borne on hook-like structures called retinacula (the lignified derivatives of the funiculus) (McDade et al., 2008).

The genus Odontonema is native to the New World and includes about 20-30 species distributed in Mexico, Central and South America and the Caribbean (Daniel, 1995). Several Odontonema species are commonly cultivated as ornamentals in nurseries, greenhouses, and gardens in tropical and subtropical regions (Daniel, 1995; Francis, 2005).

The USDA refers to the species Odontonema tubiforme as the invasive species occurring in Florida. Others disagree. Francis (2005) lists Odontonema tubiforme (Bertol.) Kuntze as a synonym of O. cuspidatum, and states that some authors propose separating O. cuspidatum and O. tubiforme into individual species or using only the name O. tubiforme. The USDA also lists Odontonema cuspidatum (Nees) Kuntze as occurring in Florida.

The ITIS database, however, says that I. tubiforme is an orthographic variant (misspelling) of the accepted species Odontonema tubaeforme (Bertol.) Kuntze. Odontonema strictum has been listed by various authorities as a synonym of both O. cuspidatum and O. tubaeforme. Physically the differences in individual plants appear in the flowers with some being much more waxy and appearing to have waxy bracts, elaborately structured while other individual's flowers are composed primarily of tubular red inflorescence.

Distribution

O. cuspidatum is native to Mexico (Daniel, 1995; USDA-ARS, 2014). It has been widely cultivated as an ornamental and can now be found naturalized in the southern United States (Florida), Central and South America, West Indies and several islands in the Pacific Ocean (see distribution table for details, Daniel 1995, 2001, 2005; PIER, 2014; USDA-ARS, 2014).

History of Introduction and Spread

According to Meyer and Lavergne (2004), O. cuspidatum (under the name O. strictum) was first collected in 1927 in Tahiti (French Polynesia) and in 1937 in Hawaii. Wagner et al. (1990) reported this species for Hawaii (under the name O. strictum) as “sometimes observed in disturbed areas” and concluded that the species “does not appear to be naturalized”. In the website treatment for the flora of Hawaii, Wagner et al. (2005) correct the name of the Hawaiian plants to O. cuspidatum and report the species as naturalized. In the West Indies, the occurrence of O. cuspidatum was reported as early as 1900 for Cuba (Urban, 1901). In 1925, Britton and Wilson reported O. cuspidatum as a strictly garden plant. By 1997, O. cuspidatum was reported as escaped (Liogier, 1997) in Puerto Rico, and in 1999 Acevedo-Rodríguez and Axelrod reported it as an “aggressive exotic, very common in the understory of secondary forests and plantations” for areas of the Rio Abajo Forest Reserve. Currently, O. cuspidatum is widespread along roadsides and understory of secondary forest in numerous localities across Puerto Rico and in areas of the El Yunque National Forest (Acevedo- Rodríguez unpublished data). In the Dominican Republic O. cuspidatum is known to occur since 1921 as a roadside plant (US Herbarium Collection). The species is considered as escaped in the most recent flora of Hispaniola (Liogier, 1995). In summary, these sources indicate that O. cuspidatum has the capacity of becoming naturalized and abundant in a relatively short period of time after being introduced as a garden plant.

Risks of Introduction to New Habitat

The risk of introduction of O cuspidatum is high. It has been widely cultivated as an ornamental in tropical and subtropical regions of the world where it has escaped and become naturalized in natural habitats (Daniel, 1995; Lorence et al., 1995; Meyer and Lavergne 2004; Liogier, 1995, 1997). The ability of this species to tolerate shaded conditions and spread vegetatively by root-suckers means that it has a high potential to colonize new areas and spread much further than it has to date (Meyer and Lavergne, 2004).

Native Habitat

O. cuspidatum can be found naturalized in wet open areas, secondary forests, forest edges, along roadsides, lowland rainforests, montane forests, pine-oak forests, and cloud forests from sea level to 1950 m (Lorence et al., 1995; Space and Flynn, 2002; Meyer and Lavergne, 2004; PIER, 2014). Because it is shade tolerant, it is able to colonize the understory of both disturbed and mature forests (Space and Flynn, 2002; Meyer and Lavergne, 2004).

Biology and Ecology

Genetics

The chromosome number for the species O. cuspidatum is unknown. However, for the genus Odontonema the chromosome number reported is n=21 (Daniel, 1995).

Reproductive Biology

Flowers in O. cuspidatum are heterostylous and require specialized pollinators to set fruits. Within its native distribution range, it is visited and possibly pollinated by hummingbirds (Daniel, 1995).

Physiology and Phenology

In warm and moist climates, O. cuspidatum has been reported flowering and fruiting throughout the year (Daniel, 1995), but in temperate climates it flowers in the autumn (Watkins, 1975; Francis, 2005).

Environmental Requirements

O. cuspidatum grows best on fertile and moderately fertile soils, with neutral pH, that are continually moist. It is shade tolerant but does not tolerate salty soils or freezing conditions and plants generally die if the ground is frozen (Watkins, 1975; Francis, 2005). O. cuspidatum grows in wet, montane, rain, and cloud forests from sea level to 1950 m in elevation (Daniel, 1995).

Temperature Tolerance and Means of Dispersal

O. cuspidatum's absolute low temperature tolerance is 30.2° F (-1° C), meaning its gradual migration north along the Florida peninsula will continue with climate change. Rarely does the ground in Florida chill below freezing, where O. cuspidatum's root-suckers spread once seeds are dispersed.

O. cuspidatum spreads by seeds and vegetatively by stem segments or root-suckers. Seeds are produced in capsules that fall off before drying, liberating the seeds (Francis, 2005). In Puerto Rico, although O. cuspidatum is common, plants produce few viable seeds and most of the stands of this species have originated from abandoned gardens or stem segments and/or roots that have been transported by streams or dumped in the woods with garden disposals. Once established, O. cuspidatum spreads mostly by root suckers. The stems also layer (root) easily when they become prostrate (Francis, 2005).