The corotú is one of the largest and most beautiful of the trees of the savanna (left photo, below). It is known in Costa Rica as the guanacaste and is the national tree of that country. It is also known as false mahogany, the earlobe tree, and the elephant ear tree, among other names.
The gomphothere is an extinct large mammal, with four tusks and some elephant-like features. The illustration at right below is from Fossil Treasures of Florida, used by permission.
How the corotú and the gomphothere are related is a fascinating story uncovered by Janzen and Martin while working in Costa Rica, and we’ll get to it shortly.
How to recognize the corotú
The corotú is an intriguing tree in its own right. As a member of the Fabaceae (bean) family, it has alternating, compound leaves and produces pods filled with beans.
The tree itself may grow to 35 meters (about 115 ft) and its trunk may exceed 1 meter (3.2 ft) in diameter. The trunk of this particular roadside tree is covered with woody vines, nearly hiding its light gray color and dark, reddish brown vertical fissures.
But the sure-fire key to recognizing the corotú lies in its distinctive pods.
The pods give the corotú, Enterolobium cyclocarpum, its scientific name:
- Enterolobium  = within (entero-) lobes (lobium) [Dave's Botanary]
- Enterolobium  = relating to the intestine (entero-) [American Heritage Dictionary]
- cyclocarpum = circle (cyclos) fruit (carpos) [Dictionary of Botanical Epithets]
It is a fruit in the shape of a circle; it has lobes that make it look like a section of intestines.
Humans have found uses for these pods. When I brought one home to show our then worker, he immediately broke it in two and took it over to the standpipe, where he held it under water for a bit. Then he rubbed his thumbs on the pulp and gradually worked up a lather! Panamanians clearly know how to use these pods as a source for soap, and it has been documented that some indigenous people in Mexico have used this soap especially for washing woolen clothes.
The pulp that lathers is on the above left and the protected seed in its cavity is on the right. And what a seed it is! Stone hard and beautiful. It needs to be scored before it will germinate.
When the pods of the corotú ripen, they fall to the ground and accumulate directly under the parent tree. Since the seeds can’t germinate without having been scored, they simply sit there. How, then, does the corotú ever expand its range, or does it?
Gompotheres to the rescue
Nearly 20 years ago, Janzen and Miller asked this question not only of the corotú, or guanacaste, but also of several other trees and plants that produced large fruits and that had no obvious way to disperse their seeds: the jobo or hog plum (Spondias sps.), the anona or custard apple (Annona reticulata), the naranjillo (Zizyphus guatemalensis), the jicaro or Mexican calabash (Crescentia alata), the trompillo (Albertia edulis), and many more. They suggested that large herbivores that lived during the pre-Pleistocene eras but that are now extinct distributed the seeds of at least 37 different species of trees found in Costa Rica. Large herbivores that lived in Central America at that time included the giant ground sloth, the giant armadillo, the native horse, and the gomphothere. These herbivores could have eaten the fruits and thereby could have carried the seeds to distant places before defecating.
Fruits in the American Northern Hemisphere may also have had their seeds distributed by large, now extinct, herbivores – fruits such as the osage orange (Maclura pomifera), pawpaw (Asimina sp.), and the Kentucky coffee bean (Gymnocladus dioica). [Janzen and Miller] Connie Barlow has written about these possibilities in Anachronistic Fruits and the Ghosts Who Haunt Them, a very good read.
Horses and cattle
Janzen and Miller also suggested that the introduced cattle and the re-introduced horses in Central America may today be dispersing at least some of the seeds formerly moved around by the extinct large herbivores. They have a picture in their paper of a horse eating, apparently with relish, a jicaro gourd (Crescentia alata), something we humans find inedible, or at the very least, extremely boring.
Here in the western province of Chiriqui, in Panama, the corotú is more widely distributed than you might think, for a tree that dumps all its fruits directly beneath its canopy. But here in Chiriqui, also, many Panamanians ride their horses as their main way of getting around. And where are the corotú trees found? Often along the roadside. It’s easy to imagine a horse tethered in the fine shade of a corotú, eating the fruits right at her feet. Then, as the horse is ridden home, somewhere along the way or more probably in a day or so, it defecates the corotú seeds, now nicely corroded by horse intestines and ready to germinate.
Note: Special thanks to Sarcozona of Gravity’s Rainbow for sharing with me her copy of the Janzen & Martin paper, which enabled me to understand a little of pre-Pleistocene ecology.