Pinus jeffreyi (Jeffrey pine) description

Pinus jeffreyi

Greville et Balfour in A. Murray 1853

Common names

Jeffrey, bull, western black, Truckee or sapwood pine (Peattie 1950); pino [Spanish], wexet [Cahuilla], hellykaay [Kumeyaay] (display at Anza-Borrego State Park).

Taxonomic notes

Syn: Pinus deflexa Torrey 1859; P. jeffreyi var. deflexa (Torrey) Lemmon 1888; P. ponderosa var. jeffreyi (Balfour) Vasey 1876; P. ponderosa ssp. jeffreyi (Balfour) Murray 1982; P. jeffreyi var. baja-californica Silba 1990 (Farjon and Styles 1997).

Generations of young botanists have had difficulty distinguishing P. ponderosa and P. jeffreyi, and it was always assumed that the two taxa were closely related; however, the truth lay in the presence of natural hybrids where Pinus coulteri occurs, such as in the Laguna, San Jacinto and San Bernardino Mountains of California, producing cones with intermediate characteristics. Analysis of nuclear and plastid DNA by Willyard et al. (2021) has now clearly shown that P. jeffreyi is in Pinus subsection Sabinianae, sister to the other species in that subsection, including P. coulteri.

Description

Trees 24-39(61) m tall, diameter 60-120(250) cm diameter, usually straight; crown conic to rounded. Bark yellow-brown to cinnamon, thick, deeply furrowed and cross-checked, forming large irregular scaly plates, with odor of lemon and vanilla during the growing season. Branches spreading-ascending; twigs stout (to 2 cm thick), purple-brown, often glaucous, aging rough. Buds ovoid, tan to pale red-brown, 2-3 cm, not resinous; scale margins conspicuously fringed. Needles 3 per fascicle, spreading-ascending, persisting (2)4-6(7) years, 12-22(25) cm × ca. 1.5-2 mm, slightly twisted, gray- to yellow-green, all surfaces with fine stomatal lines, margins finely serrulate, apex acute to acuminate; sheath (1)1.5-2.5(3) cm, base persistent. Staminate cones lance-cylindric, 20-35 mm, yellow to yellow- or purple-brown or yellow. Ovulate cones maturing in 2 years, shedding seeds and falling soon thereafter, nearly terminal, spreading, slightly asymmetric at base, ovoid-conic before opening, cylindro-ovoid when open, (10)15-30 cm, light red-brown, nearly sessile or on stalks to 0.5 cm, abaxial surface of scales not darker than or sharply contrasting in color with adaxial surface, scales in low spirals (as compared to Pinus ponderosa) of 8 or more per row as viewed from side, those of cones just prior to and after cone fall not so spreading and deflexed, thus not so much separated from adjacent scales; apophyses slightly thickened and raised, not keeled; umbo central, slightly raised, with short, slender, reflexed prickle. Seeds ellipsoid-obovoid; body ca. 1 cm, brown or gray-brown, mottled darker; wing to 2.5 cm. 2n=24 (Little 1980, Kral 1993). See García Esteban et al. (2004) for a detailed characterization of the wood anatomy.

It is often challenging to distinguish P. jeffreyi from P. ponderosa. If seed cones are available, P. jeffreyi cones have recurved umbos, so they are not prickly to the touch; except, in parts of southern California, both species have fairly prickly cones. P. jeffreyi also generally has larger cones with many more scales per cone. P. jeffreyi has more glaucous, less yellow-green foliage that is slightly thicker and less acute, compared to P. ponderosa. Vegetative buds of P. jeffreyi are non-resinous, while those of P. ponderosa are extremely resinous. Ecologically, P. jeffreyi is characteristic of higher elevation, slightly more mesic sites in areas where both species occur. Other characters that are often cited for distinguishing the species, such as bark characters or odor, have been found to be highly variable and/or inconsistent. However, for a very thorough discussion, see Chester and Strong (2022). This pair of species are an excellent example of "cryptic speciation": species that are not closely related and cannot interbreed, but are extremely similar in appearance; basically, they can tell each other apart, but we cannot. This is likely due to convergent evolution; the different species have both evolved to achieve a morphology that maximizes competitive advantage in a given environment. Many new conifer species have been described in recent decades due to the discovery of cryptic species within familiar long-recognized taxa.

Distribution and Ecology

US: SW Oregon, S through the Klamath Mtns. and Sierra Nevada of California and far W Nevada into Mexico: N Baja California Norte, at (1000)2000-3100 m on dry mountain slopes (Little 1980, Kral 1993). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001). See also Thompson et al. (1999). It is characteristic species of serpentine and other nutrient-poor soils, environments in which it grows slowly but outcompetes other trees.

Point data based on GBIF Occurrence Download https://doi.org/10.15468/dl.u47x3k, retrieved 2023.08.05, with duplicates and erroneous observations removed.

Jeffrey pine has one of the heaviest seeds found among pines whose seeds are normally dispersed by wind (rather than by birds); however, its seeds can be carried and cached by the yellow pine chipmunk, Tamias amoenus, and thus it is commonly a mammal-dispersed pine (Johnston 1994).

This species is one of the primary hosts for the dwarf mistletoe Arceuthobium campylopodum (Hawksworth and Wiens 1996).

Remarkable Specimens

A tree in the Morris Meadows, Trinity Alps, California, was discovered in December 2010 and measured at 245 cm dbh and 63.09 m tall. It actual height is probably somewhat greater; it was snowing at the time, which complicates laser measurements (Michael Taylor email 2010.12.19). The tree has an estimated wood volume (including the big reiteration shown in the photo) of 118.16 cubic meters. Michael reports that the area likely has larger and taller trees, but it's 9 miles in from the road and closed by snow until spring.

The second largest known tree is "Smoky Jack" on the Tioga Pass Road in Yosemite National Park, California, 56.7 m tall and 227 cm dbh with a wood volume of 116 m³. An even larger tree died in 2002-2003 from bark beetle attack: the "Eureka Valley Giant" was 58.5 m tall and 247 cm dbh with a wood volume of 129 m³ (Van Pelt 2001, Van Pelt pers comm. 2003.12). With the death of this tree, Pinus ponderosa assumed the title of the largest tree in subgenus Pinus.

Another giant tree, the "Wildmad Giant," was discovered in 2009 by Michael Taylor in the Trinity Mountains; this tree measures 68.9 m tall and 225 cm dbh (Michael Taylor email 2009.08.26). The odd thing is that its identity as a Jeffrey pine has not been confirmed. Its cones strongly resemble Pinus ponderosa subsp. washoensis (which has not been reported in the area and is not known to grow nearly so large) and in other respects it resembles Pinus ponderosa subsp. benthamiana. It may turn out to be a hybrid.

The oldest tree known is recorded in a tree-ring chronology was collected in 1964 at Tioga Pass, California (2591 m elevation, 37° 57'N, 119° 9' W) by C.W. Ferguson and M.L. Parker. Tree 048052 had a record of 813 rings. I don't know if this tree was alive at the time, but likely it was (NCDC 2006).

Ethnobotany

Historically, P. ponderosa was used for turpentine extraction in late 19th century California. In the absence of cones, P. ponderosa and P. jeffreyi resemble each other rather closely and occur in mixed stands. Occasionally workers would try to distill turpentine from Jeffrey rather than ponderosa sap, with explosive and sometimes tragic consequences (Mirov and Hasbrouck 1976).

Commercially, this remains an important timber species, largely interchangable with Pinus ponderosa for all practical purposes ("but the sweetish odor of the fresh-cut wood contrasts sharply with the turpentine odor of ponderosa pine" [Kral 1993]); in habitat it mainly occurs on poorer sites than ponderosa and grows more slowly, but in plantation forestry it can outgrow ponderosa, making it an attractive investment. It is primarily used in construction, because the wood is strong but soft, and can be hard to work (Farjon 2010). The resin chemistry of the two species is significantly different, though. The sap contains heptane, a highly flammable hydrocarbon that was at one point used in developing the octane scale for grading gasolines (Mirov and Hasbrouck 1976).

In dendrochronology, Brubaker and Graumlich have developed a number of chronologies from the Siskyou area, and Holmes et al. (1986) have published several chronologies from the Sierra Nevada. Jeffrey pine tree-ring data have been used in studies of climate variability, fire history, paleoseismology, air pollution (ozone), and riparian ecosystem change.

Observations

The photographs show some of the fine stands in the Sierra Juárez of Baja, but I think the Sierra San Pedro Martír stands are the most memorable. An extraordinarily extensive old-growth forest cloaks the upper elevations (above about 2000 m) of this Mexican National Park, with extensive open stands of Jeffrey and sugar (P. lambertiana) pine interspersed with white fir (Abies concolor). Locally the forest opens out into parks fringed by lodgepole pine (P. contorta), and rocky, exposed outcrops have specimens of the endemic Hesperocyparis montana. The park is readily accessed from the west by a good gravel road that leaves the Transpeninsular Highway 140 km S of Ensenada and services an astronomical observatory situated near the summit of the Sierra. In California, the mixed conifer stands of Yosemite National Park and Sequoia and Kings Canyon National Parks typically include a significant element of Jeffrey pine.

Remarks

Named for its discoverer, John Jeffrey, a 19th century Scots botanist who traveled in Oregon and California and who found the tree in the Shasta Valley of California (Little 1980). See P. balfouriana (which he also discovered) for some of Jeffrey's story.

As early as 1919, Schorger discovered that P. jeffreyi and P. sabiniana were the only two pines to contain a significant amount of n-heptane, but no terpenes, in their oleoresins (Mirov 1967), yet it took until 2021 for most taxonomists to be persuaded that the two are sister species, and genetically distant from P. ponderosa (Willyard et al. 2021).

Jeffrey pines in California have been found to be quite sensitive to air pollution, and ozone in particular causes needle death and defoliation. See the additional sources below for more information.

Citations

Chester, Tom and Jane Strong. 2022. Plants of Southern California Pinus jeffreyi and P. ponderosa var. pacifica. http://tchester.org/plants/analysis/pinus/jeffreyi_ponderosa.html, accessed 2023.08.05.

Johnston, Verna R. 1994. California Forests and Woodlands. University of California Press. Los Angeles.

Murray, A. 1853. Botanical Expedition to Oregon. No. 8. Edinburgh.

[NCDC 2006] Data accessed at the National Climatic Data Center World Data Center for Paleoclimatology Tree-Ring Data Search Page, http://hurricane.ncdc.noaa.gov/pls/paleo/fm_createpages.treering, accessed 2006.09.11, now defunct.

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. 2021. 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.