Enterolobium cyclocarpum, called elephant ear or Guanacaste tree, is found from Mexico to northern South America and the Antilles (Zuchowski 2007). In Costa Rica, it is conspicuous in the canopy of deciduous and semi-deciduous lowland forests up to 1,300 m (Janzen 1983, Zuchowski 2007). This towering species dominates pastures and grasslands of the Pacific slopes of Panama and Costa Rica (Condit et al. 2011), especially the seasonally dry Guanacaste region, named after the tree.
Guanacaste trees have broad crowns, sometimes wider than tall. Leaves are alternate and bipinnate, with small dish-like glands on the leaf raquis between pairs of leaflets. Leaflets are narrow, oblong, and feathery (Condit et al. 2011). In the Guanacaste region, entire leaf crops can be destroyed by the moth Coenipita bibitrix in July (Janzen 1983). Bark is gray and relatively smooth, with fine vertical furrows (Gentry 1993). Although the heartwood is fungus-resistant, fallen branches and logs readily decompose. Wounded trees seal gashes with water-soluble gum (Janzen 1983). Flowers—small white balls of stamens produced from January to May—are visited by small moths and beetles.
Trees yield dark reddish-brown indehiscent ear-shaped pods, which take one year to mature. Pods, approximately 12 cm in diameter, hold about 14 seeds from 1.5 to 2 cm long (Zuchowski 2007). Seeds contain insecticidal amino acid (Rehr et al. 1973) and are rich in protein and starches (Jiménez-Hernández et al. 2011). In Costa Rica, these defenses prove effective against bruchid beetles and other insects that commonly predate legume seeds (Janzen 1983). Green seeds contain saponins (Janzen 1983), plant compounds that deter herbivory or predation (Potter and Kimmerer 1989, Hoagland et al. 1996, Osbourn 1996). Nonetheless, Amazona parrots are vigorous seed predators (Zuchowski 2007). To germinate, the seed coats must be punctured, such as during digestion or soil abrasion (Janzen 1983). In Costa Rica, Liomys salvini, the spiny pocket mouse, collects seeds from dung or fallen pods. The mice hoard seeds, later nicking the seed coats to encourage germination and feeding on the seedlings, which are less toxic (Janzen 1982, Zuchoski 2007). Janzen (1982) posits that L. salvini predation ensures that guanacaste cannot reproduce in forests occupied by the mice.
Janzen and Martin (1982) suggest that Guanacaste seeds were once dispersed by Pleistocene megafauna; seeds today are dispersed mostly by the modern day equivalents, cattle and horses. Where these animals are absent, germination is usually unsuccessful, and new saplings are rare in forested areas (Condit et al. 2011). In pastures, trees receive significantly less pollen and produce fewer seeds per fruit than in continuous forest. Moreover, saplings are less viable in pastures than in forests (Rocha and Aguilar 2001). Trampling, fire, competition with grasses, and desiccation from heat keeps seed reproduction low (Janzen 1983).
Throughout Central and South America, Guanacaste trees are planted for myriad uses. Saponins in the bark and pods make them effective soap substitutes. The fungus-resistant hardwood is used for furniture, fence posts, and firewood. The distinctive spotted seeds are used in jewelry. The sap is collected to treat bronchitis, and the green fruits, to alleviate diarrhea (Zochoski 2007).
Catalog Number: US 1420061
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Original publication and alleged type specimen examined
Preparation: Pressed specimen
Collector(s): Bro. Elias
Year Collected: 1928
Locality: Sabana Larga near Barranquilla., Atlántico, Colombia, South America
- Isotype: Britton, N. L. & Killip, E. P. 1936. Ann. New York Acad. Sci. 35: 132.
Southern Pacific Dry Forests Habitat
This taxon is found in the Southern Pacific dry forests ecoregion, which is situated along the southeastern versant of the Sierra Madre del Sur Mountains including the Pacific Ocean coastal plain. These forests are a key locus of endemism for butterflies, and has the greatest diversity of scorpions and spiders in the entirety of Mexico. This ecoregion is classified in the Tropical and Subtropical Dry Broadleaf Forests biome. The Southern Pacific dry forests exhibit a moderate to high faunal species richness; for example, there are a total of 744 vertebrate taxa recorded in the ecoregion, with a particularly large number of endemic reptiles.
The ecoregion elevation ranges from sea level to 1400 metres. The climate is tropical and dry, with precipitation levels of 800 millimetres (mm) per annum. There is an extended arid season, which factor drives the prevalence of deciduous vegetation. The forests grow chiefly on shallow, well-drained soils derived from limestone. Closer to the base of the Sierra Madre del Sur Mountains, the soils are more rocky, and are derived from igneous rocks.
The dominant plant species include Mauto (Lysiloma divaricatum), Bursera excelsa and Fragrant Bursera (B. fagaroides), which are typically found in association with Pochote (Ceiba aesculifolia), Comocladia engleriana, and Trichilia americana. In the Mexican state of Michoacán, the macro plant species more generally in evidence are Ficus insipida, F. pertusa, Breadnut (Brosimum alicastrum), Licania arborea, Sideroxylon capiri and Elephant Ear (Enterolobium cyclocarpum).
There are a number of anuran species present in the ecoregion, including: Blunt-toed Chirping Frog (Eleutherodactylus modestus VU); Cloud Forest Stream Frog (Ptychohyla euthysanota NT), found from southeast Oaxaca to Guatemala and eastern El Salvador; Matuda's Spikethumb Frog (Plectrohyla matudai VU). A special status caecilian found in the ecoregion is the Mexican Caecilian (Dermophis mexicanus VU), a fossorial species that can attain lengths up to sixty centimetres. A special status salamander found in the ecoregion is the Sierra Juarez Salamander (Pseudoeurycea juarezi CR), a near-endemic known only between Cerro Pelón and Vista Hermosa in the Sierra de Juarez, north-central Oaxaca. The White-lipped Peeping Frog (Eleutherodactylus albolabris CR), a near-endemic known chiefly from Agua del Obispo, central Guerrero.
The Southern Pacific dry forests contain numerous reptilian taxa, including the following endemics: Bocourt's Anole (Norops baccatus); Taylor's Anole (Norops taylori), known only to Puerto Marquez area, in northern Acapulco, Guerrero; Simmons' Anole (Anolis simmonsi), restricted to the vicinity of Pinotepa Nacional, Oaxaca; Stegneger's Blackcollar Spiny Lizard (Sceloporus stejnegeri), restricted to the Pacific versant in the state of Guerrero, Mexico; Red Earth Snake (Geophis russatus), found in a very narrow range outside of Putla, Oaxaca; Sierra Mije Earth Snake (Geophis anocularis), known only from around Totontepec on the Atlantic versant of the Sierra Mixe, Oaxaca; Ramirez`s Hooknose Snake (Ficimia ramirezi), restricted to the Pacific versant of the Isthmus of Tehuantepec, Niltepec, Oaxaca; Halberg's Cloud Forest Snake (Cryophis hallbergi), found only in northern Oaxaca, at Sierra de Juarez and Sierra Mazateca; Isthmian Earth Snake (Geophis isthmicus), known only from the vicinity of Tehuantepec, Mexico; the endemic Macdougall's Spiny Lizard (Sceloporus macdougalli).
Characteristic mammalian fauna include the endemic Oaxacan Pocket Gopher (Orthogeomys cuniculus), restricted to several sites on the Isthmus of Tehuantepec, Oaxaca. Other mammals seen in the ecoregion include the: Lesser Long-nosed Bat (Leptonycteris yerbabuenae VU), Tropical Hare (Lepus flavigularis EN), restricted to Salina Cruz, Oaxaca to the extreme west of Chiapas; Greater Bulldog Bat (Noctilio leporinus), Coati (Nasua narica), Buller’s Pocket Gopher (Pappogeomys bulleri), Javelina (Tayassu tajacu), and Mexican Long-tongued Bat (Choeronycteris mexicana NT).
Molecular Biology and Genetics
Barcode data: Enterolobium cyclocarpum
Statistics of barcoding coverage: Enterolobium cyclocarpum
Public Records: 1
Specimens with Barcodes: 18
Species With Barcodes: 1
Enterolobium cyclocarpum, commonly known as guanacaste, caro caro, or elephant-ear tree, is a species of flowering tree in the pea family, Fabaceae, that is native to tropical regions of the Americas, from central Mexico south to northern Brazil (Roraima) and Venezuela. It is known for its large proportions, its expansive, often spherical crown, and its curiously shaped seedpods. The abundance of this tree, especially in Guanacaste Province, Costa Rica, where it is prized for the shady relief it provides from the intense sun, coupled with its immensity, have made it a widely recognized species. It is the national tree of Costa Rica.
In North America it is often called elephant-ear tree, due to the shape of the seedpods. Other common names include Devil's ear and earpod tree, parota and orejón (Spanish) or huanacaxtle (Nahuatl). In El Salvador, it is known as conacaste.
The guanacaste is a medium-sized to large tree, growing to 25–35 m tall, with a trunk up to 3.5 m in diameter. Unusual in a tree of these proportions, buttresses are completely lacking. The bark is light gray, with prominent dark reddish-brown vertical fissures. In young trees these fissures are closer together. and their confluence lends a characteristic reddish hue to the bark of guanacaste saplings. Older specimens often present broken, chipped or scarred bark.
The crown is broad and widely spreading. The height at which branches first occur along the trunk - as well as the overall tree shape - vary considerably among individuals and are habitat-dependent characteristics. Frequently, guanacaste trees grow as single specimens in a sunny pasture. Under these conditions, massive, extended, horizontal limbs emerge low on the boles, forming giant, hemispherical, widely spreading crowns. In the forest (where competition for light is intense) trees tend to become taller, and branching occurs at a higher level. Tree forms then become somewhat narrower, though crowns are still rounded, and hemispherical shapes are maintained by those that have reached the canopy.
The alternate leaves are bipinnate compound, 15–40 cm long and 17 cm broad with a 2–6 cm petiole bearing 4–15 pairs of pinnae, each pinna with 40–70 leaflets; the leaflets are slender oblong, 8–15 mm long by 2–4 mm wide. Near its base, the twiggy petiole bares a small, raised, oval gland. The leaves are confined to the outer shell of the crown, yet they are plentiful enough to make it moderately dense and green. The guanacaste is evergreen, or briefly deciduous for 1–2 months during the dry season. Most foliage is shed in December, at the start of the dry season. In late February, a growth surge is initiated that re-establishes a fresh, thick crown by April.
Concurrent with the leaves' renewal is the appearance of globular inflorescences (3 cm) in the axils of the new leaves. Supported by a long pedestal (4 cm), each spherical white head - composed of about fifty individual flowers - sports thousands of thin, filamentous stamens as its major feature. The blossoms themselves each consist of about twenty stamens and a single pistil, bound together at the base by a short, green, tubular corolla and an even shorter calyx, just 5 mm long altogether. Guanacaste flowers are very fragrant, and during intense flowering periods their odor permeates the air for many meters in all directions. In Manuel Antonio National Park near Quepos, Costa Rica, flowering lasts from late February to early April.
Surprisingly, no obvious fruiting activity immediately follows the decline of the blossom. Rather, nine or ten months pass before small, green pods first appear high in the crown by December. They reach full size by February and finally begin to ripen in March - a full year after flowering has ceased. Fruit ripening lasts from March to April, as the green pods turn brown in the guanacaste crown and are slowly shed. Vigorous trees will produce large crops on a nearly annual basis. In June, guanacaste seedlings can already be seen, germinating in the moist soil of the early rainy season.
Guanacaste fruits are large (7–12 cm diameter), glossy dark brown indehiscent and spirally-organized pods, shaped like orbicular disks. Their shape suggests the usual Mimosoideae fruit - a long, narrow, flattened pod - taken and wound around an axis perpendicular to its plane. Made of thick, soft tissue with a leathery feel, the pods contain 8-20 radially arranged seeds, 14.5–17.5 mm long, 7.8–11.2 mm wide, and 6.2–7.2 mm thick and weighing about 1 g. Guanacaste seeds are brown and marked with a conspicuous light brown or orange ring. They are very hard, resembling small stones rather than tree seeds in their strength and durability. In order for germination to occur, the hard seed coat must be broken to enable water to reach the embryo. Otherwise, the seeds will lie dormant indefinitely.
The ardillo (Cojoba arborea) and the iguano (Dilodendron costaricense) possess similar bipinnate leaves with extra-fine leaflets. Though of equally impressive stature, these two trees can be distinguished readily from the guanacaste: the ardillo has tan-colored, heavily wrinkled and rough bark - nothing like the guanacaste's unmistakably gray and vertically cracked cortex. The iguano's leaflets are serrate (an unusual feature in a bipinnate tree), while those of the guanacaste are entire.
Guanacaste trees appear to delay the onset of fruit development - some nine months - so that seed maturation will coincide with the start of the rainy season. This adaptive behavior presumably is an adaptation to give germinating seedlings as much time as possible to establish root systems before the start of the next dry season. Both the jatobá (Hymenaea courbaril) and the cenizaro (Albizia saman) exhibit similar reproductive strategies. Of course, guanacaste trees - like all deciduous and semi-deciduous species in this part of the world - share in the water-conserving benefits of dry-season leaflessness.
Guanacaste flowers are heavily visited by bees - insects that probably are responsible for pollination as well. Guanacaste seed pods, however, are completely ignored by native fauna and they accumulate on the forest floor underneath parent trees. The seeds are not eaten by any animals currently native where the tree occurs, rendering the plant an evolutionary anachronism: ir has been suggested that guanacaste pods were among the foods exploited by certain species of Pleistocene megafauna that became extinct some 10,000 years ago (e.g. giant ground sloths, giant bison). Within this scenario, the tree remains today without an effective seed-dispersing vector - except humans, that is.
As discussed above, the tough-coated guanacaste seeds do not begin to grow unless their protective covers are punctured in some way. This may be an adaptation designed to keep the seeds from germinating while still in the pods at the start of the rainy season - and very likely still underneath the parent tree after having fallen from its crown. With more time to find them, foraging ground sloths (and other extinct mammals) could eat the pods and transport the seeds to a new site. The resulting mastication and digestion of the fruits would induce seed coat abrasion, which would help seed germination.
An insect pest, common to guanacaste trees of the Costa Rican Central Valley, produces spherical green galls of 1.5 cm diameter on new shoots in February and March. Similar parasitism seems to occur on guanacaste trees of the wet, southwestern lowlands (around Palmar Sur).
Cultivation and uses
The guanacaste is among the most majestic and aesthetically pleasing of tree species in its native range. Tolerant of a wide range of rainfall levels, temperatures and soil conditions, they can thrive in most low-elevation, tropical habitats. Guanacaste trees are highly valued as ornamentals, and the shade they provide creates many an oasis on the searing and sun-baked plains in its Pacific slope habitat.
It is widely grown as a shade tree to shelter coffee plantations and for shade and forage for cattle; it also improves soil fertility by nitrogen fixation. The guanacaste is found in USDA Growth Zones 10-12.
The wood is reddish-brown, lightweight (density 0.34–0.6 g/cm³) and water-resistant; it is used to make items such as doors, windows, furniture, cabinets, and for shipbuilding. The town of La Cruz de Huanacaxtle in Nayarit (Mexico) derives its name from the fact that a cross used to stand there made of guanacaste wood.
While the seed pods are still green, they are harvested and the seeds eaten boiled in Mexico. Healthy guanacaste trees generate massive, nearly annual crops of seeds. The attractive seeds are used in Costa Rica to make jewelry. These seeds demonstrate germination rates of nearly 100%. Guanacaste seedlings then grow rapidly, often reaching over one meter in height in their first year of life. These aggressive reproductive characteristics might be beneficially exploited in reforestation projects; on the other hand, the plant is considered an invasive species in some places. Its roots are strong, and those of large trees may damage nearby structures.
- Albizia longipes Britton & Killip
- Enterolobium cyclocarpa (Jacq.) Griseb. (lapsus)
- Feuilleea cyclocarpa (Jacq.) Kuntze
- Inga cyclocarpa (Jacq.) Willd.
- Not to be confused with Inga cyclocarpa Ducke
- Mimosa cyclocarpa Jacq.
- Mimosa parota Sessé & Moc.
- Pithecellobium cyclocarpum (Jacq.) Mart.
- Prosopis dubia Kunth
- USDA (1994), Niembro Rocas (2002)
- Witsberger et al. (1982)
- Niembro Rocas (2002), Harmon (2008), PIER (2008)
- Harmon (2008)
- Janzen & Martin (1982)
- Allen (1956)
- Niembro Rocas (2002)
- Allen (1956), Niembro Rocas (2002)
- PIER (2008)
- ILDIS (2005)
- Allen, P.H. (1956): The rain forests of the Golfo Dulce. University of Florida Press, Gainesville, Florida.
- Harmon, Patrick (2008): Trees of Costa Rica's Pacific Slope - Enterolobium cyclocarpum (Jacq.) Griseb.. Retrieved 2008-MAR-31.
- International Legume Database & Information Service (ILDIS) (2005): Albizia cyclocarpum. Version 10.01, November 2005. Retrieved 2008-MAR-31.
- Janzen, D.H. & Martin, P.S. (1982): Neotropical anachronisms: The fruits the gomphotheres ate. Science 215(4528): 19-27. doi:10.1126/science.215.4528.19 PMID 17790450 HTML fulltext
- Niembro Rocas, Aníbal (2002): Enterolobium cyclocarpum (Jacq.) Griseb.. In: Vozzo, J.A. (ed.): Tropical Tree Seed Manual: 449-451. Agricultural Handbook 721. USDA Forest Service, Washington DC. PDF fulltext
- Pacific Island Ecosystems at Risk (PIER) (2008): Enterolobium cyclocarpum. Version of 2008-JAN-06. Retrieved 2008-MAR-31.
- United States Department of Agriculture (USDA) (1994): Germplasm Resources Information Network - Enterolobium cyclocarpum. Version of 1994-AUG-23. Retrieved 2008-MAR-31.
- Witsberger, D.; Current, D. & Archer, E. (1982): Arboles del Parque Deininger. Ministerio de Educacion, El Salvador.
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