RUE FAMILY (RUTACEAE) 



103. Palo rubio, yellow-prickle, yellow prickly-ash 



Zanthoxylum monophyllum (Lam.) P. Wilson 



An aromatic small tree or shrub, generally with 

 spiny twigs and trunk, further characterized by : 

 (1) short-stalked simple leaves with elliptic blades 

 11/4-4 inches long and 1^-2 inches broad, or some- 

 times larger, usually short-pointed at both ends, 

 with numerous minute gland dots, slightly spicy 

 when crushed; (2) many small whitish 5-parted 

 flowers about %6 i^^h across in terminal or lateral 

 branching clusters 1-2 inches long; and (3) 1-3 

 rounded light green fruits %6 inch long from a 

 flower, each splitting open to release 1 rounded 

 shiny black seed. The simple leaves (or single 

 leaflets) easily distinguish this from other species 

 of the genus, which have pinnate leaves. 



A deciduous tree attaining 15-25 feet in height, 

 or shrubby, with spreading crown. The gray to 

 brown bark is snioothish with vertical fissures, 

 often bearing many stout pyramidal spines i/^-% 

 inch high and 1 incli or more in vertical length 

 along the trunk. Inner bark is deep yellow, with 

 a bitter spicy taste. The green twigs, becoming 

 brown, frequently have scattered stout spines i/g 

 inch or more in length. 



The alternate leaves have slender petioles y^-Vz 

 inch long. Blades are slightly thickened, the edges 

 sometimes slightly wavy, hairless, green and 

 slightly shiny above and paler beneath. 



Branches of the flower cluster (panicle) often 

 are minutely hairy when young. Flowers appar- 

 ently are mostly male and female on different trees 

 (dioecious) . Female flowers have 5 minute pointed 

 sepals, 5 narrow white petals less than i/g inch 

 long, and pistil more than \\^ inch long with deep- 

 ly 2- or 3-lobed, 2- or 3-celled ovary and 2 or 3 



styles. Male flowers have 5 stamens about as long 

 as petals. From each female flower are formed 

 1-3 rounded podlike fruits (follicles) longer than 

 broad, each covered with tiny gland dots and 

 1-seeded. 



The sapwood is light yellow and the heartwood 

 dark brown. The wood is very hard, heavy (spe- 

 cific gravity 0.76), tough, fine-textured, and has 

 growth rings. It takes a good polish but is sel- 

 doni used because of the small size of the trees. 



Distributed chiefly in western Puerto Rico in 

 the coastal and limestone forest regions. Also in 

 Vieques, St. Croix, St. Thomas, and St. John. 



Public forests. — Guanica, Susiia. 



Municipalities where especially common. — 

 12, 36, 38. 



Range. — Hispaniola, Puerto Rico and Virgin 

 Islands, and Lesser Antilles from Montserrat to 

 St. Lucia and Barbados and in Trinidad, Bonaire, 

 and Curasao. Also in Venezuela, Colombia, and 

 Costa Rica. 



Other common names. — enrubio, espino, mapu- 

 rito, espino rubial, espino bianco, carubio, rubia 

 (Puerto Rico) ; yellow-prickly (Virgin Islands) ; 

 pino macho (Dominican Republic) ; lagarto, la- 

 garto negro, lagarto amarillo (Costa Rica) ; bosu, 

 bosiia, concha de paneque, paneque (Venezuela) ; 

 yellow prickly-ash (English) ; yellow harklis 

 (Barbados); lepuni jaune, lepine jaune, bois 

 noyer (Guadeloupe, Martinique) ; bossoea, kau- 

 baati (Dutch West Indies). 



Botanical synonym. — Fagara monophylJa 

 Lam. 



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