646 TREES OF NORTH AMERICA 



1-seeded, covered with a thin membranaceous coat. Seed ovoid, without albumen; seed- 

 coat membranaceous; hilum ventral, below the apex; embryo straight; cotyledons con- 

 tortuplicate. 



Bursera with about forty species is confined to southern Florida, the Antilles, the 

 southwestern United States and to Mexico, and Central and South America. 



The generic name is in honor of Joachim Burser (1593-1649), a German botanist and 

 physician. 



CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES. 



Leaves 5-7 rarely 3-foliolate, their rachis and petiole without wings; staminate flowers 

 in elongated many-flowered racemes. 1. B. Simaruba (D). 



Leaves usually 10-22-foliolate, their rachis and petiole wing-margined; staminate flow- 

 ers in short, usually 3-flowered clusters. 2. B. microphylla (G, H). 



1. Bursera Simaruba Sarg. Gumbo Limbo. West Indian Birch. 

 Leaves confined to the end of the branchlets, 6'-8' long, 4'-8' wide, with a long slender 

 petiole, and usually 5, rarely 3 or 7 leaflets coriaceous at maturity, oblong-ovate, oblique 



Fig. 587 



at base, contracted at apex into a long or short point, 2^ '-3' long, l|'-2' broad, with stout 

 petiolules often \' long; deciduous in early winter or occasionally persistent until the fol- 

 lowing spring. Flowers about T \' in diameter, appearing before the leaves or as they un- 

 fold, on slender pedicels \'-\' long, in slender raceme-like panicles, those of the staminate 

 plant 4 '-5' longer nearly twice as long as those of the pistillate plant; calyx-lobes and pet- 

 als 5; petals ovate-lanceolate, acute, revolute on the margins, and nearly four times as 

 long as the slender acute calyx-lobes; stamens of the staminate flower as long as the petals 

 and in the pistillate flower not more than half as long, with smaller often effete anthers. 

 Fruit in short raceme-like clusters, \'-\' long, 3-angled, with a thick dark red outer coat, 

 separating readily into 3 broad-ovate valves, and containing 1 or rarely 2 bony triangu- 

 lar nutlets rounded at base, pointed at apex, and covered with a thin membranaceous light 

 pink coat; seeds 1 or 2, triangular, rose color. 



A glabrous tree, 50-60 high, with a trunk 2|-3 in diameter, massive primary branches 

 spreading nearly at right angles, and stout terete branchlets light gray during their first 

 season, becoming during their second year reddish brown, covered with lenticular spots 

 and conspicuously marked by large elevated obcordate yellow leaf-scars. Winter-buds 



