666 TREES OF NORTH AMERICA 



roots are astringent and tonic. Of the species of the United States three are small 

 trees. 



The generic name is from Kfdva>6os, the classical name of some spiny plant. 



CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES. 

 Branchlets not spinose. 



Leaves broadly ovate to elliptical, subcordate or rounded at the base, pale and tomentose 

 below. i. C. arborescens (G). 



Leaves elliptical, acute at the base, glabrous except on the veins below. 



2. C. thyrsiflorus (G). 

 Branchlets spinose. 



Leaves mostly elliptical, rounded or subcordate at the base, glabrous. 



3. C. spinosus (G). 

 1. Ceanothus arboreus, Greene. 



(Ceanothus velutinus, var. arboreus, Silva N. Am. ii. 45.) 



Leaves broadly ovate or elliptical, acute, conspicuously gland u lar-c re n ate, dark 

 green and softly puberulent on the upper surface, pale and densely tomentose on 

 the lower surface, 2^'-4' long, l'-2' wide, with prominent veins; their petioles stout, 

 pubescent, '-!' long; stipules subulate from a broad triangular base, \' long. 

 Flowers opening in July and August on slender hairy pedicels '-!' long, from the 



axils of large scarious caducous bracts, in ample compound densely hoary-pubescent 

 thyrsoidal clusters 3'-^' long and l^'-2' wide on leafy or naked axillary peduncles 

 at the extremities of young branches. Fruit \' across and black. 



A round-headed tree, 20-25 high, with a straight trunk G'^10' in diameter, 

 dividing 4-5 from the ground into many stout spreading branches, and slender 

 slightly angled pale brown branchlets covered with short dense tomentum, becoming 

 in their second season terete, nearly glabrous, roughened with scattered lenticels and 

 marked by large elevated leaf-scars; often a shrub. Bark of the trunk dark brown, 

 about ^' thick, and broken into small square plates separating into thick scales. 



Distribution. Santa Catalina, Santa Cruz, and Santa Rosa islands of the Santa 

 Barbara group off the coast of California; most abundant and of its largest size on 

 the northern slopes of Santa Cruz; usually shrubby on the other islands, with 

 numerous slender stems. 



