Pinus ponderosa subsp. washoensis (Washoe pine) description

Pinus ponderosa subsp. washoensis

(Mason & Stockwell) E. Murray 1982

Common names

Washoe pine, ponderosa pine.

Taxonomic notes

Synonym: Pinus washoensis Mason & Stockwell 1945. For decades the status of this taxon was hotly debated, with most partisans either recognizing it as a good species or reducing it to pure synonymy with P. ponderosa. However, its cones are fairly distinctive, as are its very short needles and pollen cones. Analysis of nuclear and plastid DNA by Willyard et al. (2021a) has now shown that this taxon resides in a clade with the Pacific ponderosa pine, P. ponderosa subsp. benthamiana; and the type subspecies, P. ponderosa subsp. ponderosa. As such the three taxa have largely separate but adjunct ranges.

P. washoensis was described when California botanist Herbert Mason found what seemed to be a small-coned version of P. jeffreyi growing on the east slope of Mt. Rose in Nevada. Subsequent fieldwork delineated the extent of the Mt. Rose stand, most of which had regenerated after being logged in the 1860's (Lanner 1999), and in 1945 the trees were described as a new species (Mason and Stockwell 1945). Mason and Stockwell evidently did not consider their new pine to be a ponderosa, believing P. ponderosa subsp. benthamiana to be identical to the type collected by David Douglas in eastern Washington (P. ponderosa subsp. ponderosa). Noting that the Mt. Rose trees were distinct from those of western California (benthamiana), but failing to compare them with populations from eastern Washington, they described the Mt. Rose trees as a new species, Pinus washoensis. In the 1960s, similar populations were found in the Warner and Bald Mts of NE California and were also assigned to P. washoensis (Haller 1961, 1965; Critchfield and Allenbaugh 1965). Subsequent California investigators searching for 'P. washoensis' further north continued to make the same error, leading to reports of 'P. washoensis' from as far north as British Columbia (Critchfield 1984). The error was discovered during a review of the species by F. Lauria (1991, 1996).

Description

Trees to 60 m tall and 100 cm DBH (possibly much larger; see note below), with a straight cylindrical trunk and pyramidal crown. Bark yellow-brown to red-brown, fissured, plates scaly. Branches spreading-ascending; twigs stout, orange, aging gray, rough. Buds ovoid, red-brown, 1.5-2 cm, not resinous; scale margins fringed. Leaves (2)-3 per fascicle, spreading-ascending, persisting (2)4-6(7) years, 10-15 cm × ca. 1.5 mm, slightly twisted, gray-green, all surfaces with stomatal lines, margins finely serrulate, apex acuminate; sheath 1-2 cm, base persistent. Pollen cones cylindric, 10-20 mm, red-purple. Seed cones maturing in 2 years, shedding seeds soon thereafter, not persistent, spreading, slightly asymmetric, ovoid-conic before opening, broadly ovoid when open, 7-10 cm, tan or pale red-brown, sessile, abaxial surface of scales darker and sharply contrasting in color with adaxial surface; apophyses slightly raised, low pyramidal; umbo central, narrowly pyramidal, tapering to a short, incurved, fine prickle. Seeds ellipsoid; body ca. 0.8 cm, gray-brown; wing to 16 mm. 2n=24" (Kral 1993).

The species can best be discriminated from P. jeffreyi or the other subspecies of P. ponderosa by inspection of the mature seed cones. The crown form and the distinctive vanilla odor are essentially identical to P. jeffreyi and P. ponderosa subsp. benthamiana, but the cones are less prickly than those of the ponderosa because most of the prickles on the cone scales do not point outward, and the cones are mostly 6-10 cm long, compared to 7-15 cm for subsp. benthamiana. Jeffrey pine cones are also not prickly and are larger, typically 15-30 cm long (Lanner 1999 and my pers. obs. of material collected on Mt. Rose in 2009).

Distribution and Ecology

USA: NW Nevada and adjacent California at 2100-2500 m elevation in dry montane forests (Kral 1993). The largest population is in the southern Warner Mtns. of NE California, and it is also reported within the region from Lassen Volcanic National Park, the Bald Mountains, Last Chance Creek in Plumas County (all in California), the headwaters of Galena Creek on Mount Rose, and the Mosquito Mountains in extreme NW Nevada (Lanner 1999, Charlet 1996). I have also received a reliable report (Michael Taylor email 2009.08.26) of some very large trees in upper Hayfork Creek in the Trinity Mountains of California. These may not be pure P. washoensis but could have a hybrid origin, or may even be a new taxon; terpene and genetic studies may be needed to better understand this unique population. Specimens have also been reported from eastern Oregon (Willyard et al. 2021b). All in all, it is common to find subsp. washoensis growing near or even among subsp. ponderosa, and it may occasionally occur with subsp. benthamiana.

Distribution data for the various taxa that have been called "Pinus ponderosa", i.e. P. arizonica, P. brachyptera, P. ponderosa, and P. scopulorum, including subspecies and varieties. Data downloaded on 2021.12.15 from the Consortium of California Herbaria, the Consortium of Midwest Herbaria, and the Consortium of Pacific Northwest Herbaria, limited to geolocated records with coordinate uncertainty less than 10 km. Note that there are probably some misidentifications; for instance, P. scopulorum is unlikely to be found in the North Cascades. Most records include a link to the original herbarium record.

The IUCN does not recognize this taxon as distinct from subsp. ponderosa or subsp. benthamiana. Yet, it has a limited range and the area of occupancy seems not to have been assessed. Its conservation status is therefore "not evaluated" under IUCN criteria.

Remarkable Specimens

Michael Taylor reports that he has found and measured a tree 160 cm dbh and 50.6 m tall (Michael Taylor email 2009.09.09).

Ethnobotany

Observations

Remarks

Named for the Washoe Indians, who formerly inhabited the Mt. Rose area (Lanner 1999).

Citations

Mason, H. L. and W. P. Stockwell. 1945. A new pine from Mount Rose, Nevada. Madroño 8:61-63. Available: Biodiversity Heritage Library, accessed 2021.12.18.

Willyard, Ann, David S. Gernandt, Blake Cooper, Connor Douglas, Kristen Finch, Hassan Karemera, Erik Lindberg, Stephen K. Langer, Julia Lefler, Paula Marquardt, Dakota L. Pouncey, and Frank Telewski. 2021a. Phylogenomics in the hard pines (Pinus subsection Ponderosae; Pinaceae) confirms paraphyly in Pinus ponderosa, and places Pinus jeffreyi with the California big cone pines. Systematic Botany 46:538–561.

Willyard, A., Gernandt, D.S., López-Reyes, A., and Potter, K.M. 2021b. Mitochondrial phylogeography of the ponderosa pines: widespread gene capture, interspecific sharing, and two unique lineages. Tree Genetics & Genomes 17(6):47. doi:10.1007/s11295-021-01529-4.