Buttonwood (Conocarpus erectus) is a widespread species of terrestrial mangrove along tropical and subtropical coasts of the Americas and West Africa. It grows as a shrub or small tree on on the coastal mainland and on islands of a variety of sizes, down to the smallest vegetated islands (it is sometimes the only species of terrestrial vascular plant on an island). There are both "silver" and "green" morphs (with some intermediates), having highly pubescent (downy) and nearly glabrous (smooth) leaves, respectively. (Schoener 1988; Nettel 2008)
The distribution of this species throughout the south mid-Atlantic Islands should be confirmed.
Regularity: Regularly occurring
Global Range: Shores of central and southern Florida including Florida Keys, Bermuda, nearly throughout West Indies from Bahamas and Cuba to Trinidad and Tobago and Dutch West Indies. On both coasts of continental tropical America from Mexico south through Central America and northern South America to Ecuador and Galapagos Islands and to Brazil (Little and Wadsworth 1964). Occurrence also known along the West African coast (Little and Wadsworth 1964 and Record and Mell 1924).
The geographic range of Buttonwood includes the shores of central and southern Florida, including the Florida Keys; Bermuda; most of the West Indies; both coasts of continental tropical America from Mexico south through Central America and northern South America to Ecuador and the Galapagos Islands and Brazil; and tropical West Africa. (Little and Wadsworth 1964; Nettel et al. 2008)
Semple (1970) gives the distribution as "along the coasts of west tropical Africa, the Atlantic and Pacific coasts of tropical and subtropical North and South America and throughout the West Indies". Semple notes that pubescent-leaved individuals (as well as the typical glabrous, or smooth-leaved ones) are restricted to the northern West Indies, southern Florida, and northern Central America.
Buttonwood has been introduced to Hawaii at least twice and the silver-leaved variety sericeus is still commonly planted as an ornamental. The green-leaved variety was introduced to Oahu before 1910, possibly from Florida, and the variety sericeus was introduced to Oahu from the Bahamas in 1946. Both forms of Buttonwood have escaped cultivation and established small wild populations on some islands. In contrast to Red Mangrove, which was introduced to Hawaii and is now very common and widespread there, Buttonwood has not shown much tendency to spread beyong the initial introduction sites. In Hawaii it is cultivated and sparingly naturalized in coastal areas of Kauai, Oahu, Lanai, and Molokai. (Allen 1998 and references therein)
Buttonwood is often shrubby in form (although it can grow to 6 meters or more in height) and usually grows on the landward side of tidal mangrove swamp forests. In Florida and the Caribbean, it is the only mangrove species with alternately arranged leaves. The lance-shaped or elliptic yellow-green leaves are long-pointed at both ends, leathery and slightly fleshy, 3 to 8 cm long and 1 to 3 cm wide. Leaves have slightly winged petioles, 0.5 to 1 cm long, with 2 dot-like glands. Leaf blade edges are untoothed and usually have several dot-like glands near vein angles on the lower surface. The fragrant greenish flowers are tiny, less than 2 mm across, and crowded in balls less than 6 mm in diameter in terminal and lateral clusters. Flowers are mostly bisexual, but some trees bear heads of male flowers. Purplish-brown rounded cone-like fruits are 1 cm in diameter and are composed of many scale-like 1-seeded fruits about 3 mm long. (Little and Wadsworth 1964)
Habitat and Ecology
This species includes ever-growing shrubs to small trees with no protected terminal buds, thus requiring dormancy in winter (e.g. south Florida populations) (Tomlinson 1986). Flowering and fruiting are continuous throughout the year (Hernandez and Espino 1999). C. erectus has non-viviparous seeds which float and can be dispersed by water. Seed production is high but many are aborted or do not germinate (Tomlinson 1986). Seed viability is shown to be <12% (Hernandez and Espino 1999). The stems can sprout vegetatively (post hurricane) but experimental rooting success of cuttings was shown to be limited (Benitez-Pardo et al. 2002).
This species provides habitat for a number of species including crabs and also bald eagles (Curnutt and Robertson 1994). As an integral component of most western mangrove assemblages, C. erectus helps buffer the upper edge of highly valuable intertidal mangrove habitats, thus helping to maintain critical habitat.
Comments: In Puerto Rico, found in the mangrove swamp forests on silty shores near salt and brackish water, and sometimes also on rocky and sandy shores (Little and Wadsworth 1964). In general occurs along low muddy tide-water shores of lagoons and bays (Record and Mell 1924).
Depth range (m): 1 - 1
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Buttonwood is found in mangrove swamp forests on silty shores near salt and brackish water, usually growing on the landward side. It may also occur on rocky and sandy shores (as an ornamental, it grows in much broader conditions). (Little and Wadsworth 1964)
A study of patterns of herbivore damage to Buttonwood leaves on 74 small islands in the central Bahamas found that leaves on islands inhabited by lizards were less damaged than leaves on lizard-free islands and that pubescent (silver) leaves showed less damage than others (Schoener 1988). Furthermore, the silver pubescent form was relatively more common (as measured by percent cover) on lizard-free islands than on islands with lizards (Schoener 1987). There is evidence that at least some insect herbivores prefer green (smooth) leaves to silver (pubescent) ones (Agrawal and Spiller 2004) and much evidence from herbivory studies on other plants that leaf "hairiness" can effectively deter herbivory. Experimental introductions of lizards have reduced leaf damage (Schoener and Spiller 1999). These findings suggest that the presence of insect-eating lizards may reduce damage to Buttonwood leaves caused by insect herbivores, and that in the absence of lizards pubescent-leaved Buttonwoods may be favored over smooth-leaved ones by natural selection as a result of their greater resistance to herbivory. The full story, however, is likely more complex than this. For example, Agrawal and Spiller (2004) note that the silver and green leaves differ in ways other than hairiness (for example, in nitrogen content and leaf toughness). They also report that silver morphs are more common on protected islands, while green morphs are more common on exposed islands, suggesting that the green morph may be favored in the disturbed environment on exposed islands. Thus, some environmental conditions may favor the green form, while other conditions favor the silver form, which could explain the persistence of this polymorphism, but more experimental work is needed to clarify these interactions. Spiller and Schoener (2007) found that after hurricanes, herbivory increased dramatically, as did the disparity between herbivory levels on islands with and without lizards. The authors attributed the increase in herbivory to a reduction in numbers of both lizards and predatory arthropods.
Life History and Behavior
In a study of Buttonwood in Mexico, flowering and fruiting were found to be continuous, but seed viability was less than 12%. During the dry season, fewer than 5% of seeds germinated and only 1.6% of seedlings survived to flower after 25 to 28 months (Hernandez and Espino 1999).
Evolution and Systematics
Systematics and Taxonomy
In the northern portion of its range, silvery pubescent-leaved Buttonwood may occur along with the usual green smooth-leaved ones. These have historically been viewed as a distinct species, but today are treated either as a variety (Conocarpus erectus var. sericeus) or as examples of natural variation that do not warrant any distinct taxonomic status (Semple 1970).
Molecular Biology and Genetics
Nettel et al. (2008) have developed microsatellite markers for Buttonwood.
Statistics of barcoding coverage: Conocarpus erectus
Public Records: 0
Specimens with Barcodes: 13
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Shores of central and southern Florida including Florida Keys, Bermuda, nearly throughout West Indies from Bahamas and Cuba to Trinidad and Tobago and Dutch West Indies. On both coasts of continental tropical America from Mexico south through Central America and northern South America to Ecuador and Galapagos Islands and to Brazil. Record and Mell (1924) report occurrence on the West African coast as well. In Puerto Rico, found in the mangrove swamp forests on silty shores near salt and brackish water, and sometimes also on rocky and sandy shores (Little and Wadsworth 1964). In general occurs along low muddy tide-water shores of lagoons and bays (Record and Mell 1924).
All mangrove ecosystems occur within mean sea level and high tidal elevations, and have distinct species zonations that are controlled by the elevation of the substrate relative to mean sea level. This is because of associated variation in frequency of elevation, salinity and wave action (Duke et al. 1998). With rise in sea-level, the habitat requirements of each species will be disrupted, and species zones will suffer mortality at their present locations and re-establish at higher elevations in areas that were previously landward zones (Ellison 2005). If sea-level rise is a continued trend over this century, then there will be continued mortality and re-establishment of species zones. However, species that are easily dispersed and fast growing/fast producing will cope better than those which are slower growing and slower to reproduce.
In addition, mangrove area is declining globally due to a number of localized threats. The main threat is habitat destruction and removal of mangrove areas. Reasons for removal include cleared for shrimp farms, agriculture, fish ponds, rice production and salt pans, and for the development of urban and industrial areas, road construction, coconut plantations, ports, airports, and tourist resorts. Other threats include pollution from sewage effluents, solid wastes, siltation, oil, and agricultural and urban runoff. Climate change is also thought to be a threat, particularly at the edges of a species range. Natural threats include cyclones, hurricane and tsunamis.
Recommended conservation measures for this species include more research on population sizes. Conocarpus erectus's range is well established but updates to population sizes, fluctuations or losses need to be continued. It is recommended to expand GIS mapping and remote sensing projects (e.g. Cohen and Lara 2003) and regional scale habitat mapping (e.g. Layman et al. 2006). Demographic modeling could be useful: research is needed to establish a minimum viable population size for the taxon, as past and present exploitative uses threaten to exert continued impacts throughout its range. Continued studies of post-hurricane recovery, restoration performance, in particular restoration of multispecies complexes and mangrove associates, are needed. The value of this mangrove upper boundary species to the protection/buffering of intertidal mangroves from land-based impacts should be better articulated in the literature.
Relevance to Humans and Ecosystems
Uses: FIBER, Building materials/timber, Fuelwood, Other fuel, Tannin/dye
Comments: Used locally for fuel and for charcoal and rarely for construction. The bark contains considerable tannin.
Conocarpus erectus, one of two species in the genus Conocarpus, is a mangrove shrub and tree in the family Combretaceae growing on shorelines in tropical and subtropical regions around the world, including Florida, Bermuda, the Bahamas, the Caribbean, Central and South America from Mexico to Brazil on the Atlantic coast and Mexico to Ecuador on the Pacific coast, western Africa and in Melanesia and Polynesia. It was introduced in Kuwait because it can thrive in high temperatures and absorbs brackish water. English common names include buttonwood, buttonbush, button mangrove, button-tree, false mangrove, Florida button, Florida buttonwood, green buttonwood, grey mangrove and Zaragoza mangrove. See also the section Common names in other languages below.
C. erectus is usually a dense multiple-trunked shrub, 1–4 m (3.3–13.1 ft) tall, but can grow into a tree up to 20 m (66 ft) or more tall, with a trunk up to 1 m (3.3 ft) in diameter. The United States National Champion green buttonwood is 35 ft (11 m) tall, has a spread of 70 ft (21 m), and a circumference of 207 in (530 cm). The bark is thick and has broad plates of thin scales which are gray to brown. The twigs are brittle, and angled or narrowly winged in cross-section. The leaves are alternately arranged, simple and oblong, 2–7 cm (0.79–2.76 in) long (rarely to 10 cm or 3.9 in long) and 1–3 cm (0.39–1.18 in) broad, with a tapering tip and an entire margin. They are dark green and shiny on top, and paler with fine silky hairs underneath, and have two salt glands at the base of each leaf. The fruits are button-like (from which the common names derive), 5–8 mm (0.20–0.31 in) diameter, with no petals; they are produced in stalked panicles of 35-56 flowers. The fruit is a cluster of red to brown, small scaly, two-winged cone-like seeds, 5–15 mm (0.20–0.59 in) long. The seed heads burst when ripe, and the seeds are dispersed by water.
There are two varieties, not accepted as distinct by all authorities:
- Conocarpus erectus var. erectus - green buttonwood, leaves thinly hairy or hairless
- Conocarpus erectus var. sericeus - silver buttonwood, leaves densely silvery-hairy
The tree is used as an ornamental plant and in bonsai. The variety sericeus, with silvery leaves, is especially prized for landscaping. It is an important host plant for epiphytes. As a result of ornamental planting, it has become naturalized in Hawaii. It has been used extensively in landscaping in Kuwait and became the most abundant tree/shrub. Conocarpus is widely believed to be fodder for the African buffalo, and it is understood that this is the source of their acidic urine.
The wood is sometimes used in cabinets; it is difficult to work but takes a smooth finish. It is also used as firewood, and is reported to be good for smoking meat and fish, as it burns very hot and slowly; it also makes high quality charcoal. The bark is high in tannin, for which it has been harvested commercially.
Common names in other languages
Conocarpus erectus is known by a variety of other names in various localities, including Asokolo, Asopolo, Botoncahui, Botoncillo, Botonillo, Chene Guadeloupe, Conocarpe Droit, Estachahuite, Geli, Gra Mangrove, Grignon, Grijze Mangle, Grijze Mangrove, Iztac-cuahuitl, Jele, Kaba, Kan-chik-inche, Kanche, Kank-ank-che, Kank-che, Madre de Sal, Mangel, Mangel Blancu, Mangle, Mangle Blanco, Mangle Boton, Mangle Botoncillo, Mangle Cenizo, Mangle Garbancillo, Mangle Gris, Mangle Jeli, Mangle Lloroso, Mangle Marequita, Mangle Negro, Mangle Pinuelo, Mangle Prieto, Mangle Roche, Mangle Torcido, Mangle Zaragoza, Manglier, Manglier Gris, Mangrovia Grigia, Mangue, Mangue Branco, Mangue de Botao, Maraquito, N Ja, Paletuvier, Paletuvier Gris, Pash-chuhnul, Pataban, Saragosa, Taabche, Tabche, Witte Mangel, Witte Mangro, Wortelboom, X-kanche, Xtabche, Yana and Zaragosa.
- "Conocarpus erectus L.". Germplasm Resources Information Network. United States Department of Agriculture. 2002-02-25. Retrieved 2009-10-11.
- "Florida State and National Champions 2009". Florida Division of Forestry. 2009-08-07. Retrieved 2009-10-11.
- US Forest Service
- USDA Forest Service: Conocarpus erectus (pdf file)
- Center for Wood Anatomy Research - retrieved July 1, 2006
- Florida Forest Trees - Buttonwood (Conocarpus erectus) - retrieved July 1, 2006
- A Collection of Articles About Buttonwood from Issues of the Florida Bonsai Magazine - retrieved July 1, 2006
- Natives for your neighborhood - Buttonwood - retrieved July 1, 2006
- Mangroves-Florida's Coastal Trees - retrieved July 4, 2006