A. G. Tansley. 
274 
a full esthetic appreciation. The most beautiful trees are those of 
young middle age (say 500 to 1,000 years old), whose crowns have 
not begun to round off. The biggest trees, whose diameter is 20 
to 30 feet at the base, have a less beautiful form because of their 
more rounded tops, sparser branching and less dense foliage. 
On September 10th the main party drove from Wawona to 
Glacier Point, the highest point reached in the Sierras, on the 11th 
came back to El Portal, and on the 12th returned to Berkeley, 
staying in San Francisco or its neighbourhood till September 15th. 
Chaparral, Dry Grassland and Redwoods. 
Sunday, September 14th, was spent in an excursion to Mount 
Tamalpais, on the Sausalito peninsula, which lies on the north side 
across the Golden Gate from San Francisco, and is ascended by 
electric railway. The mountain is covered with typical Californian 
chaparral, which has the same general ecological characteristics as 
mediterranean maquis and inhabits regions exposed to the same type 
of climate. Most of the trees and shrubs seen on Mount Tamalpais 
had already been encountered on the Sierran foothills: Adenostoma 
fasciculatum , the commonest of all the chaparral shrubs, species of 
Arctostapliylos, Quercus Wislizeni, Q. chrysolepis, species of Ceanothus, 
Rhamnus californicus, Arbutus Menziesii, Umbellularia , Castanopsis, 
Eriodictyon glutinosum, with Heteromeles arbutifolia , Baccharis 
con sanguineus, etc. Quercus densijlora, a common evergreen oak of 
the Coast ranges, was scattered here and there. The characteristic 
alternation of chaparral and dry grassland with scattered oaks was 
seen here as elsewhere in California. 
There are two views of the origin of this grassland. One is 
that the grassland is a primitive vegetation occupying a drier zone 
than the chaparral. Thus the southern slopes of the hills behind 
Berkeley and Oakland are dry grassland and show no tendency to 
produce chaparral which covers the north slopes. It has been 
suggested that the scattered oaks so characteristic of it increase 
and develop up to the limit set by the soil-water supply, which is too 
scanty to permit of a closed forest vegetation or even of chaparral. 
Whether this view be true or not, it is evident that species of ever¬ 
green oak which remain low and scrubby when growing in thick 
chaparral, develop into trees in the open grassland, presumably owing 
to freedom from root competition. The other view is that the grass¬ 
land has been derived from chaparral by repeated burning of the 
latter, and that the oaks are relicts of the chaparral, freed from the 
competition of woody plants. Mr. W. S. Cooper’s detailed and 
