784 TREES OF NORTH AMERICA 



marked by occasional large lenticels and by elevated obcordate leaf-scars; or often 

 a shrub, with numerous stems sometimes only 2 or 3 tall. Bark of the trunk thin, 

 gray tinged with red, and irregularly divided into broad flat ridges, the surface ulti- 

 mately separating into long thin papery scales. Wood light, rather soft, close- 

 grained, and dark brown, with thick light brown sapwood. 



Distribution. Dry limestone ridges, and depressions in the desert; valley of the 

 Rio Grande, Texas, and southern New Mexico, southward into Mexico; most abun- 

 dant and of its largest size in Nuevo Leon between the mouth of the Rio Grande 

 and the base of the Sierra Madre. 



2. BOURRERIA, P. Br. 



Trees or shrubs, with obovate-oblong or ovate leaves involute in the bud, persist- 

 ent. Flowers on slender bracteolate pedicels, in terminal corymbose many-flowered 

 cymes, with linear-lanceolate caducous bracts and bractlets; calyx campanulate, 

 5-toothed, the divisions closed and valvate in the bud; corolla white, campanulate, 

 the lobes broadly ovate, spreading after anthesis; anthers ovate, rugulose, apicu- 

 late ; ovary incompletely 4-celled by the development of the 2 parietal placentas, nar- 

 rowed into a terminal style 2-parted at the apex, the divisions more or less coalescent; 

 stigmas capitate ; ovules attached on the back near the middle of the inner face of the 

 re volute placentas, anatropous; raphe ventral; micropyle superior. Fruit subglobose, 

 flesh thin; stone somewhat 4-lobed and separable into 4 thick-walled bony 1-seeded 

 nutlets rounded and furnished on the back with a thick spongy longitudinal many- 

 ridged appendage, flattened on their converging inner faces and attached at the apex 

 to a filiform column. Seed terete, filling the seminal cell, longitudinally incurved 

 round a rather small cavity opposite an elevated oblong scar on one of the inner 

 faces of the nutlet and connected with the hilum by a narrow passage; seed-coat 

 membranaceous, light brown; embryo axile in fleshy albumen; cotyledons plane; 

 radicle slender, elongated, turned toward the hilum. 



Bourreria with sixteen to eighteen species is confined to tropical America, one 

 species reaching the shores of southern Florida. 



The generic name is in honor of J. A. Bourrer, an apothecary at Nuremberg. 



1. Bourreria Havanensis, Miers. Strong Back. 



Leaves obovate-oblong or ovate, acute, rounded, apiculate, or emarginate at the 

 apex, wedge-shaped at the base, and entire, with thickened revolute margins, covered 

 when they unfold with soft pale caducous hairs, and at maturity thick and coria- 

 ceous, conspicuously reticulate-vennlose, dark green and lustrous, or in one form (var. 

 radula, Gray) tuberculate-scabrous or hispidulous on the upper surface, pale yel- 

 low-green and glabrous or pubescent on the lower surface, 2' 3^' long, 1' !' wide, 

 with broad orange-colored midribs and thin arcuate veins, usually persistent through 

 their second summer; their petioles slender, rigid, grooved, f'-l' long. Flowers 

 opening in the spring and late in the autumn on pedicels \' long and furnished 

 near the middle with a scarious bractlet \' in length and caducous from a persistent 

 base, in open glabrous cymes 3'-4' in diameter, with slender branches, and small 

 bracts; calyx-teeth acute, ciliate on the margins; corolla subcampanulate, creamy 

 white, with a short tube somewhat enlarged in the throat, and broadly ovate spread- 

 ing lobes |' across when expanded; ovary conical, glabrous, gradually contracted 

 into a slender exserted style divided only toward the apex or sometimes nearly 

 entire, and crowned with 2 capitate stigmas. Fruit ripening early in the autumn, 



