192 CALIFORNIA ACADEMY OF SCIENCES. 



branching near the base, but atNoyo, Mendocino County, 

 it becomes a tree with clean trunk, 10-12 inches in di- 

 ameter, unbranched for 4-6 feet and 25-30 feet in height 

 with an equal spread of branches; while on the bleak and 

 wind swept hills overlooking Point Lobos Signal Station 

 at San Francisco it forms perfectly flat mats carpeting 

 the ground for many feet in extent. Its variations in 

 form, size and pubescence of the leaves and in the form 

 and size of the thyrse are sufficiently shown in the speci- 

 mens. No. 15, Monterey, a broad-leaved form with flow- 

 ers and fruit in almost globular heads; No. 16, Santa 

 Cruz Mountains; No. 17, Mt. Tamalpais, near San 

 Francisco; No. 18, Bolinas Ridge, Marin County; No. 

 19, San Gregorio, San Mateo County (white-flowered). 

 The hybrids represented in this collection are No. 52 (C . 

 Z^oddia nil s) with. C. dcntatiis;''^o. 57 with C . ■papillosns ; 

 Nos. 64 and 65 with C. sorcdiatiis; No. 63 with C . folio- 

 sus, and No. 107 (C. Veitchianiis) with C . rigidiis. C . 

 ^oribundiiQ a second hybrid with C . dcntatus is not ex- 

 actl}^ represented by any of the forms distributed. 



13. Ceanothus arboreus Greene. 



Ceanothus arboreus. a small tree, 15-25 feet high, trunk 6-10 inches 

 in diameter, smooth, Avith a light-gray bark; branches soft-pubescent: 

 leaves ovate, acute, serrate, or often rather creuate, 2-4 inches long, green 

 and puberuleut above, whitish and soft-tomeutose beneath: flowers pale 

 blue in a compound raceme: fruit not crested. — Island of Santa Cruz; 

 common on northward slopes in the more elevated regions. The largest 

 known species, with more ample foliage than is found in any other; but 

 always tree-like in shape, with clean trunk and open but round head, like 

 a well kept orchard tree; in this particular most unlike any other Ceano- 

 thus.— E. L. Greene in Bull. Cal. Acad., ii, 144 (1886). 



This species has been referred by Prof. Sargent* to 

 C . vehitinus as a variety. It appears to me much nearer 



■■* Garden and Forest, ii, 364; Sylva of North America, ii, 45. 



