Pinus greggii (pino garabato) description

Range of Pinus greggii (Farjon and Styles 1997).

Var. greggii:

View of the site I visited near Cerro Potosí. The visible pines are almost all P. greggii, and the detail photos below are all from the mature tree at lower left [C. J. Earle, 2007.02.20, waypoint 354].

Bark on the above tree, which is 35 cm diameter [C. J. Earle, 2007.02.20].

Branch with cone and foliar units [C. J. Earle, 2007.02.20].

Recently matured cones in situ [C. J. Earle, 2007.02.20].

Closed serotinous cone [C. J. Earle, 2007.02.20].

Open cone [C. J. Earle, 2007.02.20].

Typical needle fascicles [C. J. Earle, 2007.02.20].

P. greggii nursery in operation at Dieciocho del Marzo, at the foot of Cerro Potosí [C. J. Earle, 2007.02.20, waypoint 355].

A line of mature trees mark the P. greggii nursery in Dieciocho del Marzo [C. J. Earle, 2007.02.20].

Var. australis:

Fallen cone, partly opened [C. J. Earle, 2007.02.16].

Recently ripened cone [C. J. Earle, 2007.02.16].

Whorl of first-year cones [C. J. Earle, 2007.02.16].

Representative needle fascicles [C. J. Earle, 2007.02.16].

Bark on 40 cm diameter tree [C. J. Earle, 2007.02.16].

Sapling 3 m tall [C. J. Earle, 2007.02.16].

A tree 12 m tall [C. J. Earle, 2007.02.16].

var. greggii

var. australis

Pinus greggii

Engelmann ex Parlatore 1867

Common names

Ocote, ocote chino, pino garabatillo, pino garabato, pino prieto (Flores 1996, López-Upton 1996, Perry 1991), pino greggii, palo prieto, pino prieto (Coahuila), pino ocote (Hidalgo).

Taxonomic notes

This is conventionally referred to as a closed-cone pine, but genetic studies to date do not place it in subsection Attenuatae. A study of both nuclear and plastid DNA markers found that nuclear data place all P. greggii samples together, sister to P. patula samples (Gernandt et al. 2018), and a later analysis using 161 nuclear genes with multiple samples of each taxon placed P. greggii sister to a (P. patula+P. tecunumanii) clade to form one of five distinct clades in Pinus section Australes (Cruz-Nicolás et al. 2024). This is consistent with observational evidence of introgression of P. greggii var. australis with P. patula (Donahue and Lopez-Upton 1996); artificial hybrids of the two species have also been produced (Kanzler et al. 2012). However, the plastid data placed P. greggii in a clade with P. lumholtzii and both subspecies of P. leiophylla. The nuclear DNA finding is consistent with morphological evidence, whereas the plastid DNA result is puzzling, and Gernandt et al. (2018) conclude that "whether this hypothesized case of plastid discordance that principally involves P. greggii is due to ILS, introgression, or other processes deserves further study."

Type: Mexico, Coahuila: San Antonio de las Alanzanas, near Saltillo, 1848.08.31, Gregg 402 (Farjon and Styles 1997). There are two varieties, the type and P. greggii var. australis Donahue & Lopez (1999).

Description

Trees to 25 m tall and 80 cm dbh, usually with a single straight trunk and rounded, open to dense crown. Bark first smooth, gray-brown, with age becoming darker gray-brown, scaly, comprised of rough plates separated by deep longitudinal fissures. Branchlets smooth, ridge, reddish brown to grey-brown. Foliar units form stiff, spreading tufts. Fascicle sheaths ca. 10 mm long, with chartaceous, pale brown scales, persistent but reduced in mature fascicles to 3-5 mm, exfoliating, weathering blackish brown. Leaves in fascicles of 3, persisting up to 4 years, stiff and straight, (7-)9-13(-15) cm × 1-1.2 mm, bright lustrous green, apex acute. Stomata in 6-8 lines on the outer leaf face and 3-4 lines on each inner face. Pollen cones densely clustered, ovoid-oblong to cylindrical, 15-20 × 5-6 mm, yellowish, turning yellowish brown. Seed cones in whorls of 3-8, appearing sessile, long persistent, serotinous, narrow ovoid-attenuate, usually curved with an oblique base, (6-)8-13(-15) × 3.5-5 cm (when closed, as are most cones). Seed scales ca. 80-120, purplish brown, with light brown marks of seed scales. Apophysis flat or slightly raised, rhombic to trullate, with an undulate or crenate upper margin, (weakly) transversely keeled, lustrous light brown, weathering grey. Umbo dorsal, depressed or flat, rhombic, 3-4 mm wide, with a minute, deciduous prickle, light brown to grey. Seeds obliquely obovoid, flattened, 5-8 × 3-4 mm, grey-brown to blackish brown, with a 15-20 mm yellowish to grey-brown wing (Farjon and Styles 1997). See García Esteban et al. (2004) for a detailed characterization of the wood anatomy.

Var. greggii has stiffer, shorter leaves (7-12 vs. 10-15 cm) than var. australis; the foliage of the latter usually droops. Var. greggii also has a narrower seed wing (5.5-6.4 vs. 6-8 mm) (Donahue and Lopez-Upton 1996, Farjon 2010).

Distribution and Ecology

Mexico: extreme SE Coahuila, S Nuevo Leon, SE San Luis Potosi (var. greggii); Queretaro, Hidalgo, and N Puebla (var. australis) (Farjon and Styles 1997). The species grows at 1300-2700 m elevation, with the type variety at 2300-2700 m and var. australis often lower. Precipitation is 600-800 mm per year in most areas, except on the east-facing ranges near the Hidalgo-Veracruz border, where it is 1000-1600 mm per year. Var. greggii occurs on alkaline soils (ph 7-8), while var. australis is on acidic soils (pH 4-5). It always occurs in mixed stands with hardwoods such as Quercus, Platanus, Liquidambar, and Fraxinus, and with various pines, e.g. Pinus patula, P. pseudostrobus, P. teocote, P. montezumae, P. stormiae; and on dry sites, P. cembroides and Juniperus flaccida. At higher elevations it can be found with Abies vejarii, Pseudotsuga menziesii, or Hesperocyparis lusitanica (Farjon and Styles 1997, Farjon 2010).

Distribution data from USGS (1999).

The conservation status of var. greggii was assessed as "Near Threatened" in 2013 due mainly to a very small area of occupancy (approximately 320 km², with 4 populations) and highly fragmented populations, but with little evidence of ongoing decline (Farjon 2013). That analysis is dated, however, and it is seems likely that a contemporary analysis would assign a "Vulnerable" status. The same analysis assessed var. australis as "Endangered" due to a small area of occupancy is (less than 500 km²), present in only 5 or 6 areas, with subpopulations isolated from each other by intervening agricultural land. Populations are in decline due to threats that include fires, overexploitation and deforestation associated with conversion of forest for agriculture and ranching, and suppression of regeneration by grazing (Farjon 2013b). Again, the analysis is dated and further declines in population size and area of occupancy have likely occurred. Also, for both species, climate change has since been recognized as yet another factor of decline (Martínez-Sifuentes et al. 2020), as has one of its concomitant factors: bark beetles, which have caused substantial mortality in stands of var. australis (Vergara-Pineda et al. 2014).

Geospatial distribution modeling calibrated with data for 438 known individuals indicates that habitat for Pinus greggii (both varieties) is well predicted by annual mean temperature, mean temperature of coldest quarter, and slope. These are also the primary variables for predicting climate change response. Climate change models for Mexico suggest that by the 2040-2060 period, the area of suitable habitat will decrease by 8-20% from the current 6180 km², but there are sites in both Nuevo León and Hidalgo where conditions will remain suitable; thus these constitute appropriate candidates for in situ conservation of the species (Martínez-Sifuentes et al. 2020).

The species has been evaluated for use in agroforestry. Provenance/progeny tests in Brazil, Colombia and South Africa indicate that among young trees, var. greggii grows much more slowly than var. australis, a result also seen in habitat, but the differences were reduced in the cooler climate of South Africa. Pinus greggii is best considered for forestry at tropical sites where low rainfall and cold would be limiting factors for good growth of P. patula (Dvorak et al. 1996, 2000).

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).

Remarkable Specimens

The oldest known living specimen, 123 years, was documented in a tree-ring chronology covering the period 1890-2012 (fully crossdated), collected in the mountains just south of Saltillo, Mexico by José Villanueva (doi.org/10.25921/7khz-eq04). This site was used in a reconstruction of past soil moisture balance (Stahle et al. 2016). Only one chronology has been developed for this species; older trees are likely to be found.

Ethnobotany

Traditional uses include firewood and fence posts, as well as exploitation for timber, although this has largely been incidental to the harvest of more commercially important species. Pinus greggii has been introduced for timber production in South Africa (Dvorak et al. 2000), and is suitable for use in restoration of degraded sites (Alba Landa et al. 2003). Studies of the artifical hybrid P. greggii x P. patula in South Africa indicate that for growth rates and timber production it has the potential to outperform either parent (Kanzler et al. 2012). Although rarely seen in arboreta or ornamental use, it is sometimes planted as such in Italy (Dvorak and Donahue 1992, Farjon 2010).

Observations

The photos of subsp. greggii shown here were all taken near Cerro Potosí, at 24.91888°N, 100.20963°W. The trees here sparsely cover a south-facing hillside.

The photos of subsp. australis shown here were all taken at 20.92354°N, 99.56914°W. This location is very near the Ranas ruins, outside the town of San Joaquin in San Luis Potosí. There is a good paved road to the town and a good gravel road continuing to the prominently signed ruins. The area is also very good for Pinus montezumae and P. teocote.

Remarks

The epithet honors Josiah Gregg, who collected the type specimen in 1848 (Farjon 2010). Rather like John C. Frémont a generation later, Gregg's work in botany was greatly eclipsed by his work as an explorer and author.

Citations

Alba Landa, Juan, Lilia Mendizábal Hernández, and Virginia Rebolledo Camacho. 2003. Potencialidad de siete especies forestales para la restauración desde el nivel del mar hasta 3.000 m. en Veracruz, México." Cuadernos de biodiversidad 12:4-10.

Cruz-Nicolás, Jorge, Juan Pablo Jaramillo-Correa, and David S. Gernandt. 2024. Stochastic processes and changes in evolutionary rate are associated with diversification in a lineage of tropical hard pines (Pinus). Molecular Phylogenetics and Evolution 192:108011, https://doi.org/10.1016/j.ympev.2024.108011.

Donahue, J. K. and Lopez-Upton, Javier. 1996. Geographic variation in leaf, cone and seed morphology of Pinus greggii in native forests. Forest Ecology and Management 82(1): 145-157.

Donahue, J.K. and J. Lopez-Upton. 1999. A new variety of Pinus greggii (Pinaceae) in Mexico. SIDA 18(4):1083-1093.

Dvorak, W. S., J. E. Kietzka and J. K. Donahue. 1996. Three-year survival and growth of provenances of Pinus greggii in the tropics and subtropics. Forest Ecology and Management 83: 123-131.

Dvorak, W. S., J. E. Kietzka, J. K. Donahue, G. R. Hodge, and T. K. Stanger. 2000. Pinus greggii. Pp. 52-73 in Conservation & Testing of Tropical & Subtropical Forest Tree Species by the CAMCORE Cooperative. Raleigh, NC: College of Natural Resources, NCSU.

Farjon, A. 2013a. Pinus greggii var. greggii. The IUCN Red List of Threatened Species 2013: e.T63552A3127168. https://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T63552A3127168.en, accessed 2024.01.15.

Farjon, A. 2013b. Pinus greggii var. australis. The IUCN Red List of Threatened Species 2013: e.T63553A3127230. https://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T63553A3127230.en, accessed 2024.01.15.

Kanzler, A., K. Payn, and A. Nel. 2012. Performance of two Pinus patula hybrids in southern Africa. Southern Forests: a Journal of Forest Science 74(1):19-25.

Martinez-Sifuentes, Aldo R., Jose Villanueva-Diaz, Ulises Manzanilla-Quinones, Jorge L. Becerra-Lopez, Jose A. Hernandez-Herrera, Juan Estrada-Avalos, and Actin H. Velazquez-Perez. 2020. Spatial modeling of the ecological niche of Pinus greggii Engelm. (Pinaceae): a species conservation proposal in Mexico under climatic change scenarios. iForest-Biogeosciences and Forestry 13, no. 5 (2020): 426.

Parlatore, F. 1867. Coniferae (Ordo CXCIX). Pp. 361-521 in A. P. de Candolle and Alph. de Candolle (eds.), Prodromus systematis naturalis regni vegetabilis, vol. 16, part 2. Paris (p. 396).

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

Vergara-Pineda, Santiago, Robert W. Jones, Víctor H. Cambrón-Sandoval, J. Alejandro Obregón-Zúñiga, and Armando Equihua-Martínez. 2014. Bark beetle species (Coleoptera: Curculionidae: Scolytinae) and their vertical distribution on Pinus greggii during an outbreak in the Sierra Madre Oriental of Mexico. Southwestern Entomologist 39(1):193-196.