Pinus balfouriana (foxtail pine) description

Pinus balfouriana

Greville et Balfour ex Murray 1853

Common names

Foxtail pine (Arno and Gyer 1973); the two subspecies are commonly called the "northern" and "southern" foxtail pines.

Taxonomic notes

Two subspecies, the type and P. balfouriana subsp. austrina R. Mastrogiuseppe et J. Mastrogiuseppe 1980 (syn: P. balfouriana var. austrina (R. Mastrogiuseppe et J. Mastrogiuseppe) Silba 1986).

Plants of the southern Sierra have been "shown to be genetically distinct from the type (differences in chemistry, form, foliage, cone orientation, and seeds) ... As in several other species or species complexes in Pinus, however, there is a problem with a character gradient involving related taxa. The evidence presented by D.K. Bailey (1970) and later by R.J. Mastrogiuseppe and J.D. Mastrogiuseppe (1980) could as well be used to indicate that P. balfouriana (with its two infraspecific taxa) and P. longaeva represent a single species of three subspecies or three varieties" (Kral 1993).

Description

"Trees to 22 m; trunk to 2.6 m diam., erect or leaning; crown broadly conic to irregular. Bark gray to salmon or cinnamon, platy or irregularly deep-fissured or with irregular blocky plates. Branches contorted, ascending to descending; twigs red-brown, aging gray to drab yellow-gray, glabrous or puberulent, young branches resembling long bottlebrushes because of persistent leaves. Buds ovoid-acuminate, red-brown, 0.8-1 cm, resinous. Leaves 5 per fascicle, upcurved, persisting 10-30 years, 1.5-4 cm × 1-1.4 mm, mostly connivent, deep blue- to deep yellow-green, abaxial surface without median groove but usually with 2 subepidermal but evident resin bands, adaxial surfaces conspicuously whitened by stomates, margins mostly entire to blunt, apex broadly acute to acuminate; sheath 0.5-1cm, soon forming rosette, shed early. Pollen cones ellipsoid, ca. 6-10 mm, red. Seed cones maturing in 2 years, shedding seeds and falling soon thereafter, spreading, symmetric, lance-cylindric with conic base before opening, broadly lance-ovoid or ovoid to cylindric or ovoid-cylindric when open, 6-9(-11) cm, purple, aging red-brown, nearly sessile; apophyses much thickened, rounded, larger toward cone base; umbo central, usually depressed; prickle absent or weak, to 1 mm, resin exudates amber. Seeds ellipsoid to narrowly obovoid; body to 10 mm, pale brown, mottled with deep red; wing 10-12 mm. 2n=24.

"Pinus balfouriana is the true "foxtail pine." In leaf character it is hardly, if at all, distinguishable from P. longaeva, but its strongly conic-based cones with distinctly shorter-prickled, sunken-centered umbos at once distinguish it from that species" (Kral 1993).

Distribution and Ecology

USA: California. See also Thompson et al. (1999). The two subspecies have a strongly disjunct distribution, with the two closest populations about 500 km apart. The type subspecies is found in the inner North Coast Ranges (Siskiyou, Scott, Salmon, Marble, Trinity, and Yolla Bolly Mountains) at elevations of 1,525 to 1,830 m, where it grows in open to closed-canopy pure to mixed stands (Kral 1993). There is also one collection from closely north of the California-Oregon border; however visitors to the site suspect that tree may have been planted. Hardy to Zone 5 (cold hardiness limit between -28.8°C and -23.3°C) (Bannister and Neuner 2001; subspecies not specified).

Point occurrence data based on GBIF Occurrence Download https://doi.org/10.15468/dl.d2eu5u, retrieved on 2023.08.05. Duplicate data points and observations determined to be inaccurate have been removed.

Subspecies austrina only occurs in pure or nearly pure stands in the southern Sierra Nevada from 2,750 to 3,650 m elevation, around the headwaters of the Kings, Kern and Kaweah Rivers. Nearly all trees in the southern population occur within the bounds of Sequoia National Park. Both subspecies are relatively uncommon, so of conservation concern (Kral 1993).

Oline et al (2000) observe that the northern subspecies is growing near the tops of the very tallest peaks within its range, noting that "in the north, the mountain ranges are not as high or as contiguous [as in the southern populations] -- there are only occasional isolated ridges or peaks that rise above 2000 m to provide potential P. balfouriana habitat, and the populations sizes on these ridges and peaks are small. In terms of elevation, all of the northern populations are at the extreme edge of the species' ecological limits." As a consequence, these populations have experienced isolation and genetic drift, and are now more distinct from each other than are different populations within the southern subspecies. Oline et al. (2000) also suggest that the differences between the northern populations are strong enough that they probably predated the geographic separation between the subspecies, which Eckert et al. (2008) suggest probably occurred in early to middle Pleistocene time.

It is possible that, since the northern subspecies trees have no higher elevation habitat within or near their current range, climatic warming could cause their extirpation.

Oline et al (2000) also note that some northern subspecies populations occur on serpentine-derived soils, occasionally forming pure closed-canopy stands. This is interesting because plants generally do poorly on serpentine soils, although adaptation to serpentines in northern California has also been observed for Pinus jeffreyi and Juniperus jackii. Indeed, on Mount Eddy P. albicaulis, P. balfouriana, and P. jeffreyi can be found growing together at timberline on serpentine; this is the only place I have ever seen or heard of a timberline population of P. jeffreyi. Oline et al (2000) also found some evidence that the populations growing on serpentine have differentiated; this may reflect genetic adaptation to serpentine, but, since foliage from mature trees was sampled, it may only show that there is a selection pressure affecting the trees that establish on serpentine.

I have observed the southern subspecies at the Timber Gap stand in Sequoia National Park. These trees, which include the largest trees in the southern subspecies, are growing at 3,000-3,300 m elevation on relatively deep soils derived from a calcareous schist. The closely related P. longaeva also grows best on calcareous parent materials and also grows fastest on deep soils, though both taxa can do quite well on barren talus fields. Even on good sites, growth is slow, with trees commonly taking several centuries to grow to maturity. Stands are usually pure, though at lower elevations they may also contain significant numbers of Pinus flexilis, Pinus monticola, Pinus contorta subsp. murrayana, or Abies magnifica. Stands are usually very open in structure, although a few closed-canopy stands have been described.

One consequence of the open stand structure and barren substrates is that these stands generally do not carry fire. The principal causes of tree death appear to be lightning, avalanche and rockfall. Many large trees show evidence of at least one lightning strike, and they commonly retain a strip-bark growth habit as a legacy of this misfortune. Sometimes the lightning strike ignites the tree, and the tree may be consumed if the fire is not quenched. Regeneration is common in avalanche tracks, where saplings may show evidence of repeated breakage by avalanche. The tree often grows on steep slopes beneath mountain precipices, so it is also common to see trees that have been scarred or broken by rockfall. Occasionally a tree shows scarring due to woodpecker activity, but in general, evidence of both insect and fungal attack is rare, and these are probably minor causes of mortality.

Remarkable Specimens

In the past, the largest specimen has variably been of either subspecies. Currently, the tallest known tree is in subsp. balfouriana, while the largest and oldest are in subsp. austrina.

For subsp. balfouriana, the largest tree (shown at right) is 233 cm dbh, 25.6 m tall, and 13.4 m crown spread (24 ft girth, 84 ft tall, 44 ft crown spread) (M. Kauffmann email 2023.08.05). The tallest known is dbh 121 cm, 36.0 m tall (Robert Van Pelt e-mail 1998.03.18). Both trees are located in the Trinity Alps Wilderness.

For subsp. austrina, the largest tree is 244 cm dbh, 24.1 m tall, 13.7 m crown spread (302 in girth, 79 ft tall, 45 ft crown spread) (American Forests 2021). The largest trees occur in a stand near Timber Gap in Sequoia National Park (see photo this page), where the largest tree was measured at 21.3 m tall and 261 cm dbh in 2005, and a nearby tree (probably the second-largest) was 23.8 m tall and 244 cm dbh. The 2021 American Forests numbers reported above appear to match the second-largest tree from 2005, suggesting either that the largest tree died or that it was not relocated during the most recent remeasurement. Some people who have seen these two big trees suspect that they originated as multiple-stem trees that later fused. Another photo on this page shows the Norman Clyde tree near Kaweah Gap in Sequoia National Park. It has dbh 210 cm, height 25 m. This tree appears to have fallen over in the distant past and the current live tree grew from a surviving branch that achieved apical dominance [Jack Huntamer email 2020.09.07].

The oldest record is a crossdated age of 2110 years for sample SHP7 from a specimen of subspecies austrina, collected in the southern Sierra Nevada by Tony Caprio (Arno and Gyer 1973). This is an incidental measurement, and was not the product of a systematic effort to find exceptionally old trees. Most experts expect that the tree is capable of achieving ages of 2,500 to 3,000 years, perhaps more; Pinus longaeva, a very similar species growing in a similar environment, has attained ages of over 5,000 years.

The largest tree for which I have found reliable measurements was dbh 255 cm, 23.0 m tall, crown spread 10 m, and grew near Eagle Peak in the Trinity National Forest (American Forests 1996).

Ethnobotany

I have found no records of aboriginal uses. Moreover, it has never achieved popularity in horticulture, and is quite rarely seen in botanical gardens. Its principal value to humans is thus aesthetic; the alpine groves of this ancient tree, juxtaposing its brick-red bark and vivid green foliage against blue skies and white granite, are exceptionally beautiful even in comparison with other timberline forests.

Because it lives in harsh alpine environments and achieves great age, subspecies austrina has been the subject of considerable dendrochronological research, notably by L.A. Scuderi and by Lisa Graumlich and her students, particularly Andi Lloyd (Scuderi 1993, Lloyd 1997).

Observations

The type variety can be seen to advantage at the Mount Eddy Research Natural Area in the Shasta-Trinity National Forest at 41.333°N, 122.500°W (Google Map). The stand is approached via Forest Road 17 and the Pacific Crest Trail to Deadfall Lakes. The area has about 97 ha of foxtail pine forest at elevations of about 2377-2438 m. It is almost a pure stand, with occasional individuals of Pinus albicaulis, P. jeffreyi, and P. monticola, but the trail approaching the site passes through a forest dominated by Abies concolor and Pinus monticola (Keeler-Wolf 1990). This is also probably the place with the closest road approach. The impressive Mt. Eddy stand just described is several miles in, but a number of herbarium collections have occurred very near the trailhead, described as "Along Forest Service Road 42N17C, about 0.3 mi SE of Forest Road 17, about 8.9 mi SW along FR 17 from the intersection with Stewart Springs Road and less than 50ft N. of the Trinity Co. line."

Subspecies austrina can be viewed relatively easily by visiting the Last Chance Meadow Research Natural Area in the Inyo National Forest. The site is at 36° 27' N, 118° 09' W (Google Map), and is approached via a paved road southwest of Lone Pine, California. Some trees in this large and impressive stand have attained ages of 1,000 to 1,500 years. It is found in pure stands, and in mixed stands, sometimes with limber pine (Pinus flexilis) and sometimes with lodgepole pine (Pinus contorta subsp. murrayana) (Keeler-Wolf 1990). The largest trees in the subspecies can be seen after a hike of about 4 km, to the Timber Gap area in Sequoia National Park. Access is from Mineral King, about two hours' drive east of Visalia; Google Map. Another fine stand, growing on granitic soils, can be found on Alta Peak, reached from a 12-km trail starting at the Wolverton trailhead near Giant Forest in Sequoia National Park. This trail climbs over 1,000 meters and makes for a beautiful but rather stiff day hike. Arno and Hammerly (1984) provide a good account of the Alta Peak stand. I also have a report (Jack Huntamer, 2013.09.01) of a very large (unmeasured) tree in a fine, extensive stand at 3,220 m elevation just E of Kaweah Gap in Sequoia National Park; if someone were to find and measure this tree, they might find a new record.

Remarks

"In the days when there were few roads of any sort in California, one region was as inaccessible as another, and botanical explorers, though few in number a century ago, expected nothing but hardships in the West, wherever they went. So that John Jeffrey, the Scottish explorer and first discoverer of this species, made his way to the stands of this tree on Scott Mountains, as early as 1852. Jeffrey was always a lonely man, collecting far out ahead of civilization, claiming few friends. Thus he was not quickly missed when he disappeared forever, having set out from San Diego to cross the Colorado Desert in search of new plants. He was either killed by Indians or died of thirst. No trace of his end has ever been found" (Peattie 1950). A pretty story, but it is equally plausible that Jeffrey was murdered in San Francisco during the heyday of the gold rush; his story, as best it is now known, is told by Lang (2006). The tree was named for a patron of Jeffrey's, John Balfour (Lanner 2007).

Foxtail pines, like other species in section Balfourianae, are very ancient, with very similar fossil species known from Thunder Mountain, Idaho (46 million years), as well as locales in Nevada (42 million years), New Mexico (32 million years), and Colorado (27 million years). During the glacial episodes of the Pleistocene epoch, P. balfouriana expanded its range to lower elevations, and macrofossils of the species have been found as far south as Clear Lake in northern California (Lanner 2007), but so far I have found no good evidence on how the southern populations responded to glaciation.

White pine blister rust (Cronartium ribicola), an introduced fungal disease, has afflicted this and certain other white pines (Little 1980). The disease has not yet, however, affected populations of subsp. austrina (Maloney 2011).

Citations

American Forests 1996. The 1996-1997 National Register of Big Trees. Washington, DC: American Forests.

American Forests 2021. The 2021 National Register of Champion Trees. www.americanforests.org/champion-trees/champion-trees-registry/, accessed 2023.08.05.

Arno, Stephen F. and Jane Gyer. 1973. Discovering Sierra trees. Yosemite Natural History Association. 89pp.

Arno, Stephen F. and Ramona Hammerly. 1984. Timberline: mountain and arctic forest frontiers. Seattle: The Mountaineers.

Eckert, A. J., B. R. Tearse, and B. D. Hall. 2008. A phylogeographical analysis of the range disjunction for foxtail pine (Pinus balfouriana, Pinaceae): the role of Pleistocene glaciation. Molecular Ecology 17: 1983–1997.

Keeler-Wolf, Todd. 1990. Ecological Surveys of Forest Service Research Natural Areas in California. General Technical Report PSW-125. Berkeley, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture. 177 p.

Lang, Frank A. 2006. John Jeffrey in the Wild West: Speculations on his Life and Times (1828-1854?) Kalmiopsis 13:1-12. Available: www.npsoregon.org/kalmiopsis/kalmiopsis03.html, accessed 2009.11.14.

Lloyd, A. H. 1997. Response of tree-line populations of foxtail pine (Pinus balfouriana) to climate variation over the last 1000 years. Canadian Journal of Forest Research 27:936-942.

Maloney, P. E. 2011. Incidence and distribution of white pine blister rust in the high-elevation forests of California. Forest Pathology 41(4):308–316.

Mastrogiussepe, R. J. and J. D. Mastrogiuseppe. 1980. A study of Pinus balfouriana Grev. & Balf. (Pinaceae). Systematic Botany 5:86-104.

Murray, A. 1853. Botanical Expedition to Oregon. Edinburgh, v. 8: no. 618, plate 3, fig. 1.

Oline, D. K., J. B. Mitton and M. C. Grant. 2000. Population and subspecific genetic differentiation in the foxtail pine (Pinus balfouriana). Evolution 54(5):1813-1819.

Scuderi, L. A. 1993. A 2000-year tree ring record of annual temperatures in the Sierra Nevada Mountains. Science 259:1433-1436.