Quercus densiflora was first discovered by David 
Douglas. His specimen in the Kew Herbarium is not 
precisely localised, but according to Hooker and Arnott it 
was in the Californian collection made by Douglas chiefly 
at Monterey and San Francisco. From Professor Sargent 
we learn that the species is distributed from the valley 
of the Umpqua River in Southern Oregon southward 
through coast ranges to the Santa Inez Mountains, east 
of Santa Barbara, California, and along the western 
slopes of the Sierra Nevada to Mariposa County. In 
the Sierra Nevada it ascends to an elevation of 4,000 
feet above sea-level. It is exceedingly abundant in the 
humid Californian coast region north of San Francisco 
Bay, and attains its largest size in the Redwood forests 
oi Napa and Mendocino Counties. The Species is very 
variab‘e in habit and in its leaves, sometimes occurring 
as a low spreading shrub only 1 to 10 ft. high, with small 
entire leaves. This has been distinguished as var. 
echinoides, Sargent (= var. montana, Mayr = Q. echinoides, 
R. Br., Campst.). Pasania densiflora, forma lanceolata, 
Jepson, Silva Calif. 237, has lanceolate entire or nearly 
, entire leaves 24-33 in. long. 
The wood of this oak, though hard and strong, is 
brittle and is of little value except for fuel, but its bark 
is very rich in tannin and is used in enormous quantities 
for tanning leather. Professor Jepson states that in 
1907 the annual tan harvest was about 25,000 cords, and 
to obtain this amount 100,000 trees were sacrificed every 
year, most of them being left in the forest to decay or 
to be consumed in the first forest fire. Best known as 
the Tan Oak, it is sometimes called Burr Oak and often. 
Chestnut Oak, and locally Squaw Oak and Sovereign 
Oak. The species is of great interest as being the 
solitary representative in the New World of the section 
Pasania, often regarded as a genus distinct from Quercus, 
which comprises about 100 species nearly all of which are 
confined to South-eastern Asia. Its dense erect or sub- 
erect catkins, resembling those of Castanea, small anthers 
with pollen-grains much smaller than in Quercus proper, 
and woody thick pericarp are salient characters by which 
it ae easily be distinguished from all other American 
Oaks, 
