The Pinus Washoensis
is commonly known as Washoe Pine
, as well as Yellow Pine< Go Back
Washoe pine occurs in three mountain ranges on the western rim of the
Great Basin in northeastern California and northwestern Nevada [3
It occupies a few square miles on the east slopes of Mount Rose, Nevada,
and can be found in small stands in the southern Warner Mountains and in
the Bald Mountain range of northeastern California [3
stands have been reported in Oregon and British Columbia [4
The currently accepted scientific name of Washoe pine is Pinus
washoensis Mason and Stockw. [3
]. There are no recognized
subspecies, varieties, or forms.
Washoe pine origins are uncertain. Haller [29
] proposed that Washoe
pine resulted from hybridization between either Pacific ponderosa pine
(P. ponderosa var. ponderosa) and Jeffrey pine (P. jeffreyi) or Pacific
ponderosa pine and Rocky Mountain ponderosa pine (P. ponderosa var.
scopulorum). Mirov [30
] dismissed Jeffrey pine as a possible ancestor
on chemical and morphological grounds, suggesting that Washoe pine is a
variety or mutant of ponderosa pine. Critchfield [4
] stated that Washoe
pine is a Pleistocene derivative of Rocky Mountain ponderosa pine.
Washoe pine sets more sound seed per cone in artificial crosses with
Rocky Mountain ponderosa pine than in natural intraspecific crosses.
This rare instance of heterosis for seed set in interspecific conifer
hybrids establishes a strong and direct evolutionary relationship
between Washoe pine and the Rocky Mountain ponderosa pine [17
Washoe pine hybridizes with Pacific ponderosa pine [17
] and rarely
with Jeffrey pine [4
Washoe pine typically occurs in pure stands at higher elevations along
the eastern slope of the Sierra Nevada. In the northern Sierra Nevada
and into the southern Cascade Range, it forms mixed stands with Jeffrey
pine, Pacific ponderosa pine, incense cedar (Libocedrus decurrens),
white fir (Abies concolor), California red fir (A. magnifica), and
western juniper (Juniperus occidentalis) [4,10,14,16,21]. Other common
tree associates include sugar pine (Pinus lambertiana) and quaking aspen
(Populus tremuloides var. aurea). Other associates include mountain
sweetroot (Osmorhiza chilensis), white hawkweed (Hieracium albiflorum),
greenleaf manzanita (Arctostaphylos patula), mountain big sagebrush
(Artemesia tridentata ssp. vaseyana), antelope bitterbrush (Purshia
tridentata), snowbrush ceanothus (Ceanothus velutinus), wooly wyethia
(Wyethia mollis), snowberry (Symphoricarpos vaccinioides), Idaho fescue
(Festuca idahoensis), Wheeler bluegrass (Poa nervosa), and Orcutt brome
(Bromus orcuttianus) [1,10,14,18,20,21].
Publications listing Washoe pine as a dominant species are:
Preliminary descriptions of the terrestrial natural communities of
Symposium Proceedings--plant communities of southern California 
Forest habitat types of the South Warner Mountains, Modoc County,
Montane and subalpine vegetation of the Sierra Nevada and Cascade Ranges
< Go Back
Much of the information presented here is attributed to:
Esser, Lora L. 1993. Pinus washoensis. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service,
Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available at USDA Forest Service.