Description: A small tree of the forest understory, typically with a leaning stem, sometimes multiply-stemmed. Leaves are alternate, compound, with 3-5 leaflets, one terminal and the remaining in opposing pairs. The rachis between the leaflets is conspicuously winged. The leaves and mark have an unpleasant bitter flavor if chewed, hence the local name.

Reproduction: The flowers are one of the distinctive sights in the understory of Canal area forests. They are bright pink tubes with a narrow mouth, somewhat wider at the base. Flowers are produced from October to February. The fruit consists of 4-5 berries held together in a red receptacle; the fruits themselves are green, then turn black when maturing early in the dry season.

Distribution: Generally not very common but patchy in mature forest understory. Numerous at Soberania around Limbo and in forests near Gamboa; common in places on Barro Colorado. Rare in the upper Chagres and at Sherman, and not seen near the Pacific coast.

Similar Species: One of the plants first learned at Barro Colorado due to the winged leaf rachis; only lianas (the genera Paullinia and Serjania) have similar leaves. Recall that Inga leaves, which often have wings along the rachis, are paripinnate - they lack the terminal leaflet. When flowering, Quassia is conspicuous, and flowers are often found on trails at Barro Colorado or on Pipeline Rd.

Uses: The bitter flavor is caused by a chemical named for the genus - quassain - which has insecticidal properties. The chemical can be extracted by boiling any part of the plant, including the leaves or trunk, and is used as a natural insecticide. It is one of the favorite local medicinal plants, and its use for treating various intestinal parasites is probably well-justified based on quassain's properties; like many local medicinal plants, it is also used for practically any ailment imaginable. Some people soak pieces of the trunk in alcohol to produce an insect repellent.

L., Sp. Pl. ed. 2, 553.1763 Cruceta, Guavito, Guavito amargo, Guavo amargo, Hombre grande, Puesilde, Quassia, Bitterwood Shrub or small tree, to 4 (8) m tall, glabrous; sap bitter. Leaves imparipinnate; rachis and petiole winged; leaflets 3 or 5, elliptic to oblanceolate, abruptly acuminate, gradually tapered to base, 5-16 cm long, 3-6.5 cm wide, sessile, bicolorous. Flowers 5-parted, in elongate, terminal racemes (rarely paniculate banally); branches of inflorescences and pedicels pinkish; pedicels 1-4 cm long; sepals minute, free; corolla 2.5-4.5 cm long at anthesis the slender petals glabrous, bright pink outside, white inside, soon falling; stamens 10, exserted at anthesis; filaments curiously hooked, flattened and bearded near base; anthers yellow, longitudinally dehiscent; styles connate, equal to or longer than stamens; stigma 1, simple or slightly lobed. Drupes 4 or 5 (rarely 2 or 3), black, ovoid, 1-1.5 cm long, on a broad red receptacle; seed suspended from apex. Croat 4038, 4754. Common in the forest, especially in some areas. Flowers principally in the late rainy and early dry seasons (August to March). The fruits mature within about 2 months, mostly from December to February. The fruits are eaten by white-faced monkeys (Hladik & Hladik, 1969). Southern Mexico to northern South America. In Panama, known principally from tropical moist forest in the Canal Zone, Bocas del Toro, Colón, Chiriqui, Veraguas, Coclé, Panama, and Darien; known also from tropical dry forest in Panama (Taboga Island) and from tropical wet forest in Panama and Darien.

Descripción: Árbol de 3 a 8 m de alto. Tronco, raíces, ramas, hojas y frutos con sabor amargo. Hojas imparipinnadas y alternas, con 3-5 folíolos, opuestos en el raquis. Folíolos de 5-15 x 3-7 cm, elípticos a oblanceolados, con ápice agudo o acuminado, bordes enteros y base decurrente. Las hojas presentan una coloración rojiza en la unión de los pecíolos con las ramas y en la de los folíolos con el raquis. Pecíolo alado de 5-10 cm de largo y pulvinado en la base. Raquis alado. Flores tubulares rojas o rosadas. Frutos de 2-5 drupas, de 1-1.5 cm de largo, unidas en un receptáculo carnoso y de color rojo, verdes, tornándose negros al madurar.

Datos Ecológicos: La especie crece a bajas y medianas elevaciones, en bosques húmedos o muy húmedos. En Panamá se encuentra en las provincias de Bocas del Toro, Chiriquí, Coclé, Colón, Darién, Panamá, Veraguas y la comarca de Guna Yala. Crece en los márgenes de los caminos y en las pendientes y hondonadas dentro del bosque. Florece y fructifica de octubre a febrero. Las flores son visitadas por colibríes y mariposas. Las semillas son dispersadas por animales.

Especies Parecidas: A menudo se confunde con varias especies del género Paullinia (Sapindaceae), pero Paullinia es un bejuco con los bordes de los folíolos dentados, además presenta estípulas y savia lechosa, lo cual no ocurre en Quassia. Por el pecíolo y el raquis alado se puede confundir con algunas especies del género Inga, pero en Inga las hojas son paripinnadas y tienen una glándula entre cada par de folíolos.

Usos: La madera se emplea en la carpintería, fabricación de cajas y obras internas. Todas las partes de la planta tienen propiedades medicinales, se recomienda en el tratamiento de las afecciones gástricas, dispepsia, diabetes, inapetencia, anemia, diarreas, flatulencias, congestiones hepáticas y lombrices intestinales. Pedazos del tronco, las raíces, los frutos y las semillas, se colocan en un recipiente con alcohol y se emplean como repelente contra insectos.