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 ACERACEAE. 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. 



1. 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. spicaturri. 



