BURSERACEAE. 171 
BurseraA. West Indian Birch. 
(Family Burseraceae). 
Tender resinous trees with pa- 
pery-flaking red or brown bark 
and extremely light, soft and ut- 
terly worthless wood: subdecidu- 
ous. Twigs glabrous, moderate, 
terete: pith round, continuous, 
light brown. Buds solitary, ses- 
sile, small, depressed globose, with 
about 3 more or less short-pointed 
seales. Leaf-scars alternate, half- 
round, low: bundle-traces 3: sti- 
pule-scars lacking. Leaves, if 
present, like the twigs closely re- 
semble those of mahogany, from 
which in bark, wood and habit it 
greatly differs, as it does in the 
technical characters of flowers and 
fruit. 
An effective contrast of the bark 
of Bursera and Swietenia is af- 
forded in figures 9 and 10 of the 
text accompanying part 13 of Hough’s American Woods, of 
which thus far 325 species have been distributed in cross sec- 
tion, and tangential and radial longitudinal sections. 
Twigs light brown, warty. (Gumbo limbo). B. Simaruba. 
