Pinus cembroides

Zucc. 1830

Common names

Mexican piñon, stoneseed piñon, threeleaf piñon, pinyon pine (Elmore and Janish 1976); pino piñonero (Kral 1993).

Subsp. orizabensis: Orizaba piñon.

Taxonomic notes

Notes on the piñons in general

The piñons constitute Pinus sect. Parrya, with P. cembroides as the first species described, in 1830. P. monophylla and P. edulis were described soon after in 1845 and 1848. However, even to the end of the 20th century many authors did not recognize any other widespread piñon species, so much of the literature must be interpreted with that in mind. Systematics of the group finally started to come clear with a morphological study by Malusa (1992) but, as in so many conifer groups, much more conclusive results came from integrative studies using morphological and multiple molecular lines of evidence, especially in work by Syring et al. (2007), Flores-Rentería et al. (2013), and Montes et al. (2019, 2022). The 2022 analysis was particularly useful, as it considered over 80 specimens from widespread locations within all putative taxa in sect. Parrya, revealing relationships within and between subsections Nelsoniae (the unique Pinus nelsonii), Balfourianae (the ancient "foxtail" pines), Rzedowskiae (the "big cone" piñons), and Cembroides (the "small cone" piñons). A simplified version of Figure 6 from that analysis is shown at right, demonstrating cladistic relationships between the taxa in sect. Parrya. Note the following:

• Pinus culminicola, P. discolor, P. johannis and P. remota are species in a monophyletic lineage distinct from P. cembroides and its close relatives. There is a close relationship between P. johannis and P. discolor, with evidence of introgression in a sample from San Luis Potosí, the one area where the two taxa have a fairly close spatial connection.
• Pinus cembroides, P. lagunae, and P. orizabensis have a more complex relationship. Each of these taxa was sampled from several locations within its range. Results support treating P. lagunae as a distinct species and P. orizabensis as a subspecies of P. cembroides. Montes et al. "hypothesize that the divergence of P. cembroides and P. lagunae occurred during the Pleistocene and the current geographic distribution of P. lagunae may be the result of climatic fluctuations during that time, resulting in an expansion of its range towards the south and its subsequent persistence in the southern Baja California refuge." There is evidence of interbreeding between these three taxa, and particularly, that P. lagunae has introgressed with P. cembroides
• Pinus monophylla, P. quadrifolia, P. edulis and P. californiarum are distinct species. The old idea (Lanner 1974) that P. quadrifolia originated as a hybrid is not supported, although some individuals of P. quadrifolia show evidence of admixture with P. californiarum and P. monophylla. Introgression has occurred between P. californiarum and P. edulis to produce the nothospecies P. × kohae. P. californiarum and P. monophylla, both one-needled pines of very similar appearance, are quite distinct; as Montes et al. (2022) conclude, "Morphological, phylogenetic, paleoclimatic, geographical, ecological, and genetic evidence support the recognition of P. californiarum and P. monophylla as separate species."
• The big-cone piñons, Pinus pinceana, P. maximartinezii, and P. rzedowskii, are clearly distinct taxa in the molecular analysis. Their morphological differences and status as distinct species have long been acknowledged.

Notes on Pinus cembroides

Per the preceding discussion, Pinus cembroides consists of two subspecies, the type and subsp. orizabensis. The two are closely similar in morphology, subsp. orizabensis are nested among subsp. cembroides samples in the molecular phylogeny, and the geographic distribution of subsp. orizabensis is likewise nested within that of subsp. cembroides.

Pinus cembroides Zucc. subsp. cembroides: Type: Mexico, México, Sultepec, Santa Cruz, F. Karwinski s.n. (holo M). No synonyms.

Pinus cembroides Zucc. subsp. orizabensis D.K.Bailey 1983: Type: Mexico, Puebla, Soltepec, along Highway 140 ca. 10 km SW of San Salvador el Seco, D.K. Bailey 83-01 (holo MEXU). Syn. P. orizabensis (D.K.Bailey) D.K.Bailey & Hawksw. 1990; P. cembroides Gordon 1846 non Zucc. 1832.

Description

Subsp. cembroides: Trees to 15 m tall. Leaves in fascicles of 2-3, lax or sometimes stiff, 30-50 × 0.6-1.0 mm, variably dull green to glaucous green. Seed cones 3-4.5 × 4-5.5 cm when open, with usually 15-18 fertile scales. Seeds 10-13 × 6-10 mm with a 0.6-1.0 mm thick seed coat; fresh endosperm pinkish (Farjon 2010). See García Esteban et al. (2004) for a detailed characterization of the wood anatomy.

Subsp. orizabensis: Trees to 10 m tall with an irregular rounded crown. Bark scaly, blackish-grey, with shallow orange fissures (Bailey 1983). Leaves in fascicles of 3-4 (about 80% in 3s), mostly 4-6 cm long, glossy dark green on the outer face and glaucous white on the inner faces, stomata mostly confined to the inner faces. Fascicle sheath semi-persistent, the basal scales curling back into a rosette. Seed cones 4.5-7.5 × 5-8 cm when open, with up to 25 fertile scales, typically 30-35 × 16-20 × 2-3 mm (length × width × thickness), smooth (not wrinkled). The thin scales curl in at the edges on drying to give pointed scale corners. The golden-brown seeds average larger 14-17 mm long, the endosperm is white in fresh seeds but turns pink on drying. The 1 mm rudimentary seedwing usually remains in the cone after seed dispersal (description compiled from Gordon 1846, Bailey 1983, Bailey and Hawksworth 1988, Bailey and Hawksworth 1990, Perry 1991, Farjon and Styles 1997, and M.P. Frankis' 1998 observations of the cultivated tree at Kew).

Distribution and Ecology

Subsp. cembroides: USA: Arizona, New Mexico, Texas (Lanner 1981, Kral 1993); Mexico: Coahuila, Hidalgo, Nuevo Leon, Puebla, San Luis Potosi, Tamaulipas, Veracruz; at elevations of 700-2400 m, mainly in piñon-juniper woodland (Perry 1991). See also Thompson et al. (1999). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001).

The IUCN classifies this subspecies as "Least Concern" for human impacts due largely to its vast geographic range with many discrete populations, and relatively minor levels of human impact.

Subsp. orizabensis: Mexico: Puebla, Tlaxcala, and Veracruz, in the area around Pico de Orizaba, at 2100-2800 m altitude. There is a long dry season from November to May, with 800-900 mm of annual precipitation mostly falling during the summer. Frost may occur in December-January. Soils are volcanic in origin. Typically found in open woodlands or locally dense forests, sometimes in pure stands but usually mixed with Juniperus deppeana or J. flaccida; other associates may include Pinus pseudostrobus and Quercus sp. It is locally sympatric with subsp. cembroides, e.g. near Ajalpán in Puebla (Farjon 2013). USDA hardiness zone 8.

The IUCN classifies this subspecies as "Endangered" by human impacts due to a small extent of occurrence and area of occupancy within a severely fragmented habitat. There has been continuous and ongoing decline in population size due to land clearance for agriculture, and there are no recorded efforts to conserve the taxon, nor does it occur in any protected areas (Farjon 2013).

Pines of the Pinus cembroides complex. Purple diamonds are P. cembroides ssp. cembroides; purple stars are P. cembroides ssp. orizabensis. Green is P. culminicola, blue is P. discolor, brown is P. johannis, red is P. lagunae, and gold is P. remota. Based on GBIF.org downloads https://doi.org/10.15468/dl.pfuj4k (P. culminicola), https://doi.org/10.15468/dl.vvju45 (P. remota), and https://doi.org/10.15468/dl.5k7x9y (all other taxa), accessed 2023.03.09, with location uncertainty <10 km, and location duplicates removed.

Subsp. orizabensis is a principal host for the mistletoe Arceuthobium pendens (Bailey 1983, Hawksworth and Wiens 1996).

Remarkable Specimens

The largest specimen of subsp. cembroides on record is diameter 90 cm, height 20 m, crown spread 13 m, located in Big Bend National Park, Texas (American Forests 1996). Larger trees probably occur in Mexico.

The oldest known living specimen, 351 years, was documented in a tree-ring chronology covering the period 1595-2012 (fully crossdated), collected at 2314 m elevation just east of Cuauhtémoc, Coahuila, Mexico by José Villanueva (doi.org/10.25921/0fb2-ha85). This site was used in a dendroclimatic reconstruction of soil moisture balance (Stahle et al. 2016).

Ethnobotany

Both subspecies are chiefly exploited for their edible seeds, which are mostly sold in local markets. The wood probably has only local and limited uses, e.g. as firewood or fenceposts, but larger trees may occasionally be used to prepare saw timber (Farjon 2010, 2013).

A cultivated specimen of subsp. orizabensis at Kew Gardens, UK, was 12 m tall and 32 cm dbh in 1984 (A.F. Mitchell); it was thought to be about 50-60 years old. This tree is a very attractive specimen, and the species well deserves further planting as an ornamental.

As noted above, the species has been useful in dendrochronology. A 2023 review found 8 tree-ring chronologies developed using this species, and over 20 published studies in areas including fire history, streamflow, dendroclimatology, and tree growth.

Observations

No data as of 2023.11.03.

Remarks

Piñon is a Spanish word meaning "pine" so the term "piñon pine" is redundant. The epithet cembroides notes certain similarities in appearance to the Swiss stone pine Pinus cembra (Zuccarini 1830), while the epithet orizabensis reflects a distribution near Orizaba, the tallest mountain in Mexico.

The resin composition is very close to P. johannis (Zavarin and Snajberk 1985, 1986).

Bailey and Hawksworth (1990) first described this taxon after observing the cultivated tree at Kew, then mislabeled as P. nelsonii, and carrying out detective work to locate matching wild-origin herbarium material, followed by a visit to the Orizaba region which proved to be its homeland.

Citations

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

Bailey, D. K. 1983. A new allopatric segregate from central Mexico and a new combination in Pinus cembroides at its southern limits. Phytologia 54: 89-99.

Bailey, D. K. and F. G. Hawksworth. 1990. Change in status of Pinus cembroides subsp. orizabensis (Pinaceae) from central Mexico. Novon 2: 306-307.

Farjon, A. 2013. Pinus cembroides subsp. orizabensis. The IUCN Red List of Threatened Species 2013: e.T34185A2849785. https://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T34186A2849840.en, accessed 2023.03.09.

Flores-Rentería, Lluvia, Ana Wegier, Diego Ortega Del Vecchyo, Alejandra Ortíz-Medrano, Daniel Piñero, Amy V. Whipple, Francisco Molina-Freaner, and César A. Domínguez. 2013. Genetic, morphological, geographical and ecological approaches reveal phylogenetic relationships in complex groups, an example of recently diverged pinyon pine species (subsection Cembroides). Molecular Phylogenetics and Evolution 69(3):940–49. https://doi.org/10.1016/j.ympev.2013.06.010.

Gordon, G. 1846. New plants from the Society's garden. J. Hort. Soc. London 1: 234-239.

Little, Elbert L. 1968. Two new pinyon varieties from Arizona. Phytologia 17:329–342 (p. 331). Available: Biodiversity Heritage Library, accessed 2023.03.10.

Malusa, James. 1992. Phylogeny and biogeography of the pinyon pines (Pinus subsect. Cembroides). Systematic Botany 17(1):42-66. https://doi.org/10.2307/2419064.

Montes, José Rubén, Pablo Peláez, Ann Willyard, Alejandra Moreno-Letelier, Daniel Piñero, and David S. Gernandt. 2019. Phylogenetics of Pinus subsection Cembroides Engelm. (Pinaceae) inferred from low-copy nuclear gene sequences. Systematic Botany 44(3):501–518. https://doi.org/10.1600/036364419X15620113920563.

Montes, José‐Rubén, Pablo Peláez, Alejandra Moreno‐Letelier, and David S. Gernandt. 2022. Coalescent‐based species delimitation in North American pinyon pines using low‐copy nuclear genes and plastomes. American Journal of Botany 109(5):706–726. https://doi.org/10.1002/ajb2.1847.

Stahle, David W., Edward R. Cook, Dorian J. Burnette, Jose Villanueva, Julian Cerano, Jordan N. Burns, Daniel Griffin, Benjamin I. Cook, Rodolfo Acuna, Max C.A. Torbenson, Paul Sjezner, and Ian M. Howard. 2016. The Mexican Drought Atlas: Tree-ring reconstructions of the soil moisture balance during the late pre-Hispanic, colonial, and modern eras. Quaternary Science Reviews 149:34-60. doi: 10.1016/j.quascirev.2016.06.018

Syring, J., K. Farrell, R. Businsky, R. Cronin, and A. Liston. 2007. Widespread genealogical nonmonophyly in species of Pinus subgenus Strobus. Systematic Biology 56(2):163–181

Zavarin, E. and K. Snajberk. 1985. Monoterpenoid and morphological differentiation within Pinus cembroides. Biochem. Syst. Ecol. 13: 89-104.

Zavarin, E. and K. Snajberk. 1986. Monoterpenoid differentiation in relation to the morphology of Pinus discolor and Pinus johannis. Biochem. Syst. Ecol. 14: 1-11.

Zuccarini, J. G. 1830. Plantarum novarum vel minus cognitarum, quae in Horto Botanico Herbarioque Regio Monasensi servantur, descriptio. Abh. Math.-Phys. Cl. Konigl. Bayer. Akad. Wiss. 1:287-396. Available: Biodiversity Heritage Library, accessed 2023.03.09.

See also

Elwes and Henry 1906-1913 at the Biodiversity Heritage Library. This series of volumes, privately printed, provides some of the most engaging descriptions of conifers ever published. Although they only treat species cultivated in the U.K. and Ireland, and the taxonomy is a bit dated, still these accounts are thorough, treating such topics as species description, range, varieties, exceptionally old or tall specimens, remarkable trees, and cultivation. Despite being over a century old, they are generally accurate, and are illustrated with some remarkable photographs and lithographs.

Peattie 1950.

FEIS database.