Pinus monophylla

Torrey et Frémont 1845

Common names

Singleleaf piñon (or pinyon) (Arno and Gyer 1973); one-leaved, Gray, Frémont, or Nevada nut pine (Peattie 1950).

Taxonomic notes

Subsection Cembroides (Perry 1991). Syn: Caryopitys monophylla (Torrey & Frémont) Rydberg; Pinus californiarum D.K. Bailey; P.cembroides Zuccarini var. monophylla (Torrey & Frémont) Voss (Silba 1986).

Gernandt et al. (2003), in a study of chloroplast DNA sequences in piñon pines, found that this species is most closely related to P. juarezensis and P. quadrifolia. This is not surprising. P monophylla hybridizes with P. quadrifolia (Kral 1993), and Lanner (1974) asserts that P. quadrifolia arose through the hybridization of P. monophylla with P. juarezensis. Having examined the three taxa in their habitat in San Diego County and adjacent Baja California Norte, I agree with him. Lanner (1974a, 1999) also asserts that the 2-needle piñons of the New York Mountains in southern California are actually P. monophylla, whereas other authorities maintain those trees are a disjunct population of P. edulis; on this point I have no opinion, not having seen the trees in question. Lanner (1999) alludes to unpublished isozyme work that supports the hypothesis that the New York Mountains trees are P. monophylla, but offers no details. Interestingly, P. monophylla is also known to hybridize with P. edulis (Kral 1993). Although the two taxa are now almost completely disjunct (detailed map), it is entirely possible that they were sympatric at some time in the past -- for instance, during glaciopluvial times about 18,000 years ago -- in which case the New York Mountains population could have had a hybrid origin. DNA studies would be required to test this notion, though.

Description

Trees 5-9(14) m tall and up to 50 cm diameter, strongly tapering, much branched; crown usually rounded, dense. Bark red-brown, irregularly furrowed or cross-checked, scaly. Branches spreading and ascending, persistent to near trunk base; twigs stout, orange-brown, aging brown to gray, sometimes sparsely puberulent. Buds ellipsoid, light red-brown, 0.5-0.7 cm, resinous; scale margins fringed. Needles 1 (rarely 2) per fascicle, ascending, persisting 4-6(10) years, 2-6 cm x 1.3-2(2.5) mm, stout, curved, terete (though often 2-grooved), gray-green, all surfaces with stomatal lines, margins entire, apex subulate; sheath 0.5-1 cm, scales soon recurved, forming rosette, shed early. Staminate cones ellipsoid, ca. 10 mm, yellow. Ovulate cones maturing in 2 years, shedding seeds and falling soon thereafter, spreading, symmetric, ovoid before opening, broadly depressed-ovoid to nearly globose when open, 4-6(8) cm, pale yellow-brown, nearly sessile; apophyses thickened, slightly raised; umbo subcentral, raised or depressed, nearly truncate, apiculate. As with other piñons, the seeds rest in a deep cone-scale declivity and upper cone scale tissue holds the seeds in place, so seeds do not readily fall out and are readily available to avian dispersers. Seeds cylindric-ellipsoid; body 15-20mm, gray-brown to brown, wingless, edible. 2n=24 (Little 1980, Kral 1993, R. Lanner email 1999.12.20).

Range

USA: Idaho, Utah, Nevada, Arizona, California; Mexico: Baja California Norte. 1000-2300 m. Prefers dry, gravelly slopes in semiarid country (Little 1980, Kral 1993).

Within its range, it is generally the predominant tree species, dominating large areas throughout isolated mountain ranges of the Great Basin. In most of that area it forms piñon-juniper woodlands with species of Juniperus, primarily J. osteosperma; the pine tends to predominate at higher/wetter elevations, and the juniper at lower/drier ones. At high elevations it commonly occurs with bristlecone pine, Pinus longaeva. In other areas it may be found growing with P. coulteri, P. ponderosa, P. jeffreyi, Abies concolor, Cupressus arizonica, Juniperus californica, J. occidentalis, and even Ephedra viridis. In some areas it occurs with one of two other piñons, P. edulis and P. juarezensis, and it hybridizes naturally with both species (see Taxonomic notes above). For more detail on vegetation associations, see the FEIS. See also Thompson et al. (1999).

Big tree

Diameter 135 cm, height 15.2 m, crown spread 15.8 m, located in Washoe County, Nevada (American Forests 2008).

Oldest

In about 2007, Scotty Strachan and Franco Biondi sampled a living tree named MIN-108 in the Pilot Range, Nevada, that crossdated to 1106 AD. This is the oldest living tree record yet found (S. Strachan email 2008.07.13). A few years earlier, Biondi and Strachan found a tree in the Pine Grove Hills of Nevada that crossdated to an age of 888 years (RMTRR 2006).

Dendrochronology

Has been used in stable-isotope studies, historical archeology (dating the construction of old mine buildings), air pollution assessment, and a wide variety of climate studies (Bibliography of Dendrochronology). NOAA lists 15 chronologies for this species (NOAA Tree Ring Search Page).

Ethnobotany

The large, nutritious seeds were a staple food for native americans living within the range of this species, and are still gathered with enthusiasm. The wood is used primarily for fuel and for fenceposts; in the historic period, the species was widely exploited to fuel railroad locomotives and to produce charcoal for silver smelters (FEIS database). It is also locally harvested for Christmas trees (Burns and Honkala 1990).

Observations

Easy to find within its range. Piñon-juniper woodlands are particularly widespread and well-developed in east-central Nevada, while the largest and most impressive individual trees I have seen have been in Joshua Tree National Park, near the southwest range limits of the species. It is also a reasonably common ornamental, tolerant of relatively wet climes, and can be found in arboreta and larger parks in the eastern US and Great Britain.

Remarks

The only pine bearing a single needle per fascicle.

Singleleaf piñon is the state tree of Nevada (Kral 1993).

This species, along with Pinus edulis, is host to the dwarf mistletoe Arceuthobium divaricatum (Hawksworth and Wiens 1996). Trees may also be afflicted by insects including the pinyon ips (Ips confusus), pinyon needle scale (Matsucoccus acalyptus), pinyon sawfly (Neodiprion edulicolus) and mountain pine beetle (Dendroctonus ponderosae); the cone predators Eucosma bobana and Dioryctria albovittella (moths); and by fungal diseases including pinyon blister rust (Cronartium occidentale), singleleaf pine needle cast (Bifusella pini), and black stain root disease (Leptographium [=Verticicladiella] wageneri) (Burns and Honkala 1990, Scharpf 1993).

Citations

Gernandt, D.L., A. Liston and D. Piñero. 2003. Phylogenetics of Pinus subsections Cembroides and Nelsoniae inferred from cpDNA sequences. Systematic Botany 28(4): 657–673.

See also

Blackburn, W.H., and P.T. Tueller. 1970. Pinyon and juniper invasion in black sagebrush communities in east-central Nevada. Ecology 51(5): 841-848.

Farjon and Styles (1997).

Lanner (1981).

Lanner (1983).

Malusa (1992).

Muir (1894).

Zavarin, E., K. Snajberk and R. Debry. 1980. Terpenoid and morphological variability of Pinus quadrifolia and its natural hybridization with Pinus monophylla in northern Baja California and adjoining United States. Biochemical Systematics and Ecology 8(3): 225-235.