''Tabernaemontana donnell-smithii'' is an evergreen tree in the dogbane family Apocynaceae commonly known as the horse balls tree. In Spanish, it is ''huevos de caballo'', ''cojones de burro'', ''cojón de mico'', or ''cojotón''. The name, ''huevos de caballo'', comes from the oval shape of the tree's hanging fruit. It is native to Mexico and Central America. The type locality is San Felipe, Retalhuleu in

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by H ...

. ''Tabernaemontana donnell-smithii'' is similar to ''

Tabernaemontana glabra ''Tabernaemontana glabra'' is an evergreen tree from the family Apocynaceae, native to Mexico, Central America, and northwestern South America (Colombia, Peru, Ecuador, Bolivia , image_flag = Bandera de Bolivia (Estado).svg , ...

'', except that its leaves and flowers are smaller and its fruit is larger. ''Tabernaemontana donnell-smithii'' lives in a variety of habitats, including various types of forest, the forest edge, and pastures. It grows up to tall, although the height is partially dependent on the habitat. Trees living in secondary growth areas, forest edges and pastures are generally shorter but broader than those in forests. The flowers are yellow, and may appear at different times of the year depending on the location. Foster and McDiarmid found that the slow growing fruit is about long and weighs an average of about . The fruit is enclosed in a woody

husk Husk (or hull) in botany is the outer shell or coating of a seed. In the United States, the term husk often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective ...

which represents more than three-quarters of the fruit's weight. When the fruit is open, a slit forms in the husk permitting access to the

aril An aril (pronounced ), also called an arillus, is a specialized outgrowth from a seed that partly or completely covers the seed. An arillode or false aril is sometimes distinguished: whereas an aril grows from the attachment point of the see ...

s, each of which covers a seed. The fruit of ''Tabernaemontana donnell-smithii'' is eaten by birds such as parrots, and by the white-headed capuchin, and the seeds are eaten by birds such as flycatchers,

motmot The motmots or Momotidae are a family of birds in the order coraciiformes, which also includes the kingfishers, bee-eaters and rollers. All extant motmots are restricted to woodland or forests in the Neotropics, and the largest are in Middle A ...

honeycreeper The typical honeycreepers form a genus ''Cyanerpes'' of small birds in the tanager family Thraupidae. They are found in the tropical New World from Mexico south to Brazil. They occur in the forest canopy, and, as the name implies, they are specia ...

s, manakins and woodpeckers. Many primarily

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores were ...

birds eat the fruits opportunistically late in the dry season, when the most of the fruit ripens and when insects are relatively scarce. Its seeds are dispersed primarily by birds. A study by McDiarmid, Ricklefs and Foster found that birds also help the seeds germinate, both by removing the

s from the seeds and also by scarifying the seeds. The bark contains the

alkaloids Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar st ...

tabernanthine Tabernanthine is an alkaloid found in ''Tabernanthe iboga''. It has been used in laboratory experiments to study how addiction affects the brain. Tabernanthine persistently reduced the self-administration of cocaine and morphine in rats. Phar ...

and voacamine. The seeds contain the alkaloids coronaridine and tabersonine.

References

{{Taxonbar, from=Q9079781 Plants described in 1893 donellsmithii Flora of Mexico Flora of Central America Flora of Costa Rica Flora of Guatemala Flora of Panama Flora of Belize Flora of Nicaragua Flora of Honduras