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Pinus pinceana

Pinus pinceana
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Scientific name: Pinus pinceana  G. Gordon  1858

Synonyms: Pinus latisquama Engelm. 

Common names: Weeping pinyon pine, Pince's pinyon pine (English),  Pino piñonero-llorón, Pince piñon (Spanish)

 

Description

Tree to 10(-12) m tall, with trunk to 0.3 m in diameter. Bark gray and smooth at first, becoming brownish gray, flaking, and finally breaking up into flat, rectangular plates separated by shallow, narrow, vertical and horizontal cracks. Crown broad and rounded, with numerous irregularly placed, arching branches dangling at the ends and clothed with downswept foliage to give a weeping appearance. Twigs light gray, hairless. Buds 3-6 mm long, not resinous. Needles in bundles of three (or four), each needle (5-)6-12(-14) cm long, straight and slender but stiff, lasting 2-3 years, grayish green. Individual needles with lines of stomates on the inner faces and sometimes with one or two inconspicuous lines of stomates on the outer face, an undivided midvein, and two large resin canals touching the epidermis of the outer face near the outer corners. Sheath about 10 mm long, curling back and soon shed. Pollen cones 8-10 mm long, purplish tan. Seed cones 5-10 cm long, variously egg-shaped, with 30-60 seed scales, purple before maturity, ripening shiny reddish brown, opening just enough to release the seeds and breaking off with part of the 1-2 cm long stalk. Seed scales diamond-shaped, weakly attached, with deep depressions for the seeds, the exposed face weakly or prominently thickened and angled outward, crossed by a sharp ridge peaking in a small diamond-shaped umbo. Seed body 10-14 mm long, wingless or with a rudimentary wing remaining attached to the seed scale.

The species name honors Robert T. Pince (ca. 1804 - 1871), a nurseryman specializing in fuchsias in Devon, England, who has no apparent connection to the species, except for its being named after him.

Discontinuous in the Sierra Madre Oriental of northeastern Mexico, from central Coahuila to northern Querétaro and Hidalgo. Scattered in dry, open woodland with numerous succulents on rocky slopes and in gulches; 1,100-2,300(-2,700) m.

 

Conservation Status

Red List Category & Criteria: Least Concern

Pinus pinceana's distribution extends over a distance of more than 750 km from north to south. Its extent of occurrence is well in excess of 20,000 km². Due to the disjunct and scattered distribution of stands the area of occupancy is probably less than 2,000 km². It is known from at least 17 localities and subpopulations could be considered to be severely fragmented. Despite a reported lack of regeneration throughout its range and a potential threat from fuelwood collection, there is currently no indication of significant recent or current decline. Consequently, an assessment of Least Concern is appropriate.

Subpopulations are scattered and disjunct, especially in the southern parts of its range. They range in size from 300 to 10,000 trees.  They occur in three main areas: northern (Coahuila, Zacatecas, Nuevo León) central (San Luis Potosí) and southern (Hidalgo and Querétaro). Northern populations show distinct genetic variation from those in the central and southern parts of its range. Common garden experiments indicate that subpopulations also show local adaptations to variations in rainfall and average temperatures.

This species occurs in arid areas at altitudes ranging from 1,100 m asl (Nuevo León) to 2,300  asl. Rainfall is between 350 and 600 mm per year with higher rainfall in the southern part of its range. It usually occurs as scattered individuals among Pinus cembroides and Drooping juniper (Juniperus flaccida). Associated vegetation varies, depending on the amount of rainfall, although it is dominated by sclerophyllous and deciduous desert shrubs.

Although regeneration in some parts of its range has been reported to be poor, probably as a result of over grazing, more recent field work has found evidence of adequate regeneration throughout its range. Firewood collection may also be a potential threat.

As this species only forms a small tree or large shrub, its timber has limited use. Large branches may be used for firewood. Seeds are edible but produced infrequently.

Pinus pinceana is poorly represented within Mexico's network of protected areas: it is estimated that less than 8% of the total population is protected in situ. The recently discovered stands in Nuevo León occur within the Parque Nacional Cumbres de Monterrey. Pinus pinceana is listed on the Mexican National Red List and the Red List for Nuevo León as a species requiring special protection.

 

Varieties: -

 

References

  • Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
  • Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
  • IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.


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