Odontonema cuspidatum
(Cardinal’s guard)

Preferred Common Name

• Cardinal’s guard

Other Scientific Names

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

International Common Names

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

Local Common Names

• Ecuador: lava botellas
• Mexico: coral de jardín; flor de chupa miel; flor de chuparrosa
• Paraguay: clavo de fuego
• Saint Lucia: firespike

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Scrophulariales
•                         Family: Acanthaceae
•                             Genus: Odontonema
•                                 Species: Odontonema cuspidatum

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).

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 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.

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.

Soil drainage

• free

Soil reaction

• neutral

Soil texture

• light
• medium

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).

O. cuspidatum is an aggressive species that can grow forming dense thickets in the understory of secondary and relatively unaltered forests. For example, Meyer and Lavergne (2004) reported dense monospecific stands of this species (between 100 m² and 500 m²) in the understory of secondary low- and mid-elevation wet forest in Hawaii, Tahiti, and Samoa; a similar pattern has been reported for Puerto Rico (Acevedo-Rodríguez and Axelrod, 1999). O. cuspidatum is also invading native montane rainforest in Tahiti (Meyer and Lavergne, 2004). In Cuba, O. cuspidatum is listed as one of the 100 most noxious plants invading natural habitats (Oviedo Prieto et al., 2012).

• 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
• Tolerant of shade
• Highly mobile locally
• Benefits from human association (i.e. it is a human commensal)
• Long lived
• Fast growing
• Reproduces asexually

• Ecosystem change/ habitat alteration
• Monoculture formation
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - smothering
• Pest and disease transmission
• Rapid growth
• Rooting

• Highly likely to be transported internationally deliberately
• Difficult to identify/detect in the field

O. cuspidatum is an economically important species in the horticultural and nursery trade. It is widely cultivated as an ornamental in tropical and subtropical areas for its conspicuous red flowers (Watkins, 1975; Daniel, 1995; Francis, 2005). It is also popular in gardens because it attracts butterflies and hummingbirds that feed on the nectar (Watkins, 1975).