ACERACEAE, 123 
STAPHYLEA. Bladdernut. 
Deciduous shrubs with soft pale wood with minute diffused 
ducts and fine medullary rays; moderate rounded twigs; rather 
large continuous pith; opposite half-round somewhat raised 
leaf-scars with about 10 bundle-traces in a C- or O-shaped se- 
ries; no stipule scars; ovoid sessile buds with 2 or 4 exposed 
scales; petioled trifoliolate or odd-pinnate leaves with ovate or 
lanceolate crenulate or serrate rather large leaflets; smallish 
white polypetalous perfect flowers in stalked clusters; and large 
bladder-like 3-celled fruit with few seeds. 
1. Leaflets three. 2. 
Leaflets usually 5 or 7. S. pinnata. 
2. Terminal leaflet very short-stalked. . S. Bumalda. 
Terminal leaflet distinctly stalked. S. trifolia. 
Family ACERACEAEF. Maple Family. 
A rather small family of trees and shrubs yielding impor- 
tant cabinet woods, and the source of the much esteemed ma- 
ple sugar: containing some of the best shrubs and street trees. 
Acer. Maple. Box-elder, 
Deciduous shrubs or trees with commonly rough bark in 
age; rather brown often hard wood with minute diffused ducts 
and rather fine but distinct medullary rays; round homogeneous 
pale pith; slender to stout nearly terete twigs; opposite narrow 
U-shaped leaf-scars with usually 3 or 5 bundle-traces in a single 
series; ovoid or conical buds, occasionally stalked and with 2 
valvate outer scales but mostly with several visible pairs of 
scales; usually palmately veined and lobed leaves (exceptionally 
unlobed, and palmately or pinnately compound in the group 
Negundo, etc.); usually imperfect and small often greenish 
polypetalous or apetalous flowers variously clustered; and 
rather large paired wing-fruits. 
t. Buds distinctly stalked, with 2 valvate scales. 2. 
Buds essentially sessile. 3. 
2. Twigs and buds glabrous. A. pennsylvanicum. 
Twigs and buds pubescent: leaves serrate. A. spicatum. 
