Description: A small or medium-sized tree with long, compounds leaves with a terminal leaflet (21 or so leaflets), the entire leaf up to 1 m in length. The leaf rachis and branches have sharp spines, and the trunk has large, blunt, woody spines. Trunk spines are evenly dispersed, nearly cylindrical at the base. The leaves have small clear dots ("pellucid dots"), best visible by viewing through a lens in front of a light. Leaves are not fragrant when crushed.

Reproduction: Completely deciduous toward the end of the dry season, when tiny flowers are produced in dense clusters. Fruits are small berries that mature during the wet season.

Distribution: Zanthoxylum setulosum is common along Pipeline Road, and there are a few in Gamboa. Otherwise, it is not particular common in forest, and not frequently seen in yards or on farms.

Similar Species: There are four species of Zanthoxylum in the area, all with long, compound leaves and spines on the leaves and trunk; all have pellucid dots in the leaves (a family characteristic). They are best distinguised by the trunk spines, which vary in shape and number; eg, LK zantbe Z. ekmanii LK2 has flat spines, and LK zantp1 Z. panamense LK2 has large, cylindrical spines densely packed at the base of the trunk. Many Zanthoxylum have fragrant, citrus-smelling leaves when crushed, but Z. setulosum does not. Leaves of Zanthoxylum can also be confused with LK sponmo Spondias, LK2 but the latter has no spines and gives a turpentine-like odor from crushed leaves.

Dioecious tree, (3) 6-12 (20) m tall; trunk 10-15 (20) cm dbh, armed, the prickles many, large, corky, oval or rounded in basal outline, the apex rounded with a sharp point set somewhat off-center; outer bark +/- smooth, light brown, with many raised lenticels; inner bark tan; wood pale yellow, the cambial layer fluted. Leaves alternate, pinnate, 15-50 cm long, conspicuously pubescent (particularly below), the trichomes erect, simple; petioles terete; rachis margined above, sometimes bearing small prickles; leaflets 15-27, subopposite, +/- sessile, ovate to oblong or oblong-elliptic, acuminate, acute to rounded at base, usually inequilateral at base, 2.5-10 (15) cm long, 1.5-3.5 cm wide, entire or crenulate, obscurely pellucid-punctate, sometimes glabrate in age above, rarely with a few prickles on midrib below. Panicles terminal or upper-axillary, +/- congested, to 21 cm long, the branches short, sparsely puberulent; pedicels 2-3.7 mm long, glabrous or crisp-pubescent; flowers unisexual, 5-parted, 2.7 mm long; calyx ca 1 mm long, usually glabrous, rounded at apex; petals elliptic, boat-shaped, spreading, white to greenish-white, the veins prominent, 2-2.3 mm long, rounded at apex, glabrous or inconspicuously pubescent inside; stamens of staminate flowers 5, included or exserted and spreading.. 1.7-2.7 mm long, the anthers about as long as or much shorter than filaments, the pistillode small, 1-4-lobed, the styles 1-4; pistillate flowers not seen. Fruits of (2) 4 (5) follicles, tan or brown, glabrous, the valves persistent, muricate, the inner valve whitish, curling from the base to force seed from follicle; seeds 1 per follicle, +/- globose or ovoid, black, shiny, 2.5-3.3 mm long, suspended on a strong slender fiber. Croat 5430. Frequent in the forest. Flowers in the late dry season (March and April). The fruits develop soon but may persist for a long time, maturing from April to October (sometimes to December). Leaves are shed in the dry season, and the trees may be bare for more than a month. Ants may inhabit old spines and hollow parts of some stems. Panama and possibly Costa Rica. In Panama-, known principally from tropical moist forest on the Pacific slope in the Canal Zone, Panama, and Darién known also from tropical dry forest in Los Santos, from premontane moist forest in Coclé (La Pintada), and from premontane wet forest on Coclé (El Cope). See Fig. 299 and fig. on p. 20.

Descripción: Árbol de 10 a 20 m de alto. Tronco con espinas cónicas agrupadas y concentradas en la parte superior de la base. Corteza exterior amarillenta. Hojas imparipinnadas y alternas, de 15-50 cm de largo, con 15-27 folíolos, subopuestos o alternos en el raquis. Folíolos de 3-14 x 2-4 cm, elípticos a oblongos, con ápice agudo o acuminado, bordes enteros o crenulados y base aguda. Láminas foliares aromáticas y con puntos translúcidos. Pecíolo de 5-10 cm de largo. Raquis a veces con espinas en forma de aguijón. La especie es dioica. Flores blancas o verdosas, aromáticas. Frutos en cápsulas, de 0.3-0.5 cm de diámetro.

Datos Ecológicos: La especie crece a bajas y medianas elevaciones, en bosques secos o húmedos. En Panamá se encuentra en las provincias de Coclé, Colón, Darién, Herrera, Los Santos, Panamá y Veraguas. Florece y fructifica de marzo a diciembre. Las flores son visitadas por abejas y otros insectos. Las semillas son dispersadas por la abertura de los frutos y los animales.

Especies Parecidas: Especies parecidas: A menudo se confunde con LK zantp1 Zanthoxylum panamense LK2 , pero en Z. panamense las espinas del tronco son más pequeñas y dispersas. También se puede confundir con LK zantbe Zanthoxylum ekmanii LK2 , pero en Z. ekmanii LK2 las espinas del tronco son triangulares y aplanadas.

Usos: Las espinas y la corteza del tronco tienen usos medicinales.