90 ACERACEAE 



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 0-shaped 

 series; 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; small- 

 ish 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. 



ACEB. Maple. Box-elder. 



Deciduous shrubs 1 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 homo- 

 geneous pale pith; slender to stout nearly terete twigs; oppo- 

 site 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. spicatum. 



