CLASSIFICATION OF ANGIOSPERMS. 705 



flowers are white and in compound cymes, the outer being sterile 

 and large and showy. The fruit is a reddish, globular, very 

 acid drupe, clinging to the branches all winter. The Snow-ball 

 or guelder-rose of the gardens is a sterile variety of this species. 

 Another variety (edule) is also cultivated on account of its edible 

 fruits, particularly in Canada and the Northern United States. 



FIG. 392. Fruiting branch of Viburnum prumfolium. 



A number of species of Viburnum are rather common in 

 various parts of the United States, as the Maple-leaved arrow- 

 wood (V . acerifolium) , which is a small shrub with deeply 

 3-lobed, coarsely dentate leaves and small, nearly black drupes ; 

 Arrow-wood (V . dentatum), with broadly ovate, coarsely den- 

 tate leaves and blue drupes, which become nearly black when 

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