78 PROCEEDINGS OF THE CALIFORNIA 



Mr. Bolancler read the following article : 



*o 



Enumeration of Shrubs and Trees growing in the vicinity of 

 the mouth of San Francisco Bay. 



BY HENRY N. BOLANDER. 



The territory in question is divided naturally into three parts : 



1. The northern part of the peninsula of San Francisco, with an undulating 

 and hilly surface, consists of drifting sand, with a small per centage of humus 

 mingled with it. 



2. The Oakland Hills, running N. 54° W. mag., from the Bay of San Pablo 

 to San Leandro, a distance of twenty-three miles, with the adjacent slopes and 

 valleys. Heavy clayey soil predominates ; but where shrubs and trees grow it is 

 mostly a loose, light, and slightly sandy soil. 



3. That part of Marin County between San Rafael, the head of Tomales Bay 

 and Bolinas Bay, forming a triangle, with a hilly surface, the ridges running 

 N. 54° W. mag. Soil a heavy clay, in the valleys and on bare hills; or a 

 light, slightly sandy loam among shrubs and trees. 



In all parts a metamorphic sand-stone underlies the soil. 



Berberis (Mahonia) Aquifolium Pursh. ., 

 A low evergreen shrub, three to four feet high, not gregarious; in clay soil 

 on the hill sides ; rare. 



Dendromecon rigidum Benth. 

 A shrub with slender upright branchlets, four to six feet high, rare; on white 

 sand-stone, Oakland hills, third range eastward, not gregarious. 



Rh us diversiloba Torr. and Gray. Poison Oak. 

 Everywhere, deciduous, exceedingly variable, three to eight feet high. 



Negundo Aceroidcs Mcench. Box-Elder. 

 A medium sized tree, twenty to thirty feet high ; common among the Oakland 

 hills, on banks of creeks. 



Acer macrophyllum Pursh. Large-Leaved Maple. 

 Common on the banks of Walnut Creek, N.W. of Mount Diablo; fifty to 

 seventy feet high, and two to five feet in diameter, in light sandy soil. 



JEsculus Cahfoniica Nutt. Horse-Chestnut. 

 Mostly a shrub, seldom a medium sized tree, largest on the banks of creeks 

 and moist hill sides ; grows commonly in groups. Common. 



Euonymus Occidentalis Nutt. Spindle-Tree. 

 A shrub seven to fifteen feet high, with slender upright branches ; in swampy 

 places, near the head of Tomales Bay ; rare. 



Frangida Californica Gray. California Buckthorn. 

 Very common, variable, four to ten feet high ; evergreen, gregarious, in 

 clayey soil. 



Ceanothus thyrsijforiis Esch. California Lilac. 

 Very common, and variable in size, sometimes handsome trees ; exceedingly 



