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Conservation status

Juniperus martinezii

Pérez de la Rosa 1985

Common names

Taxonomic notes

This taxon was described in 1985 from a population of with small seed cones (5-7 mm), 1-2 seeds per cone and foliage somewhat drooping but branchlets tips erect (Pérez de la Rosa 1985). Based largely on the drooping foliage, the taxon was quickly renamed as a variety of the widespread flaccid-leaved juniper of Mexico: Juniperus flaccida Schtdl. var. martinezii (Pérez de la Rosa) Silba 1985. The varietal classification was widely adopted.

In 2006, RAPD sequencing for the three generally recognized varieties of J. flaccida revealed it to be polyphyletic, and J. martinezii was then restored to species rank. The analysis of Adams et al. (2006) found it to be sister to J. durangensis within a clade in turn sister to J. flaccida; the authors also provide detailed discussion of the historical changes in taxonomic thinking about this group of species.

Type: Mexico, Jalisco, Sierra Cuatralba, 4 km E of the village of El Cuarento; J. A. Perez de la Rosa 661 (holotype IBUG; isotypes F, K).

Description

Dioecious shrub (rarely a tree) 4-8 m tall, with a round to broadly conical crown. Bark is grey-brown, exfoliating in interlaced strips. Branches are grey, the terminal branchlets flaccid or pendulous. Leaves are usually opposite and not imbricate, (1.5-)2(-2.5) mm long, 1.0(-1.5) mm wide, ovate to elongate-ovate, acuminate, mucronate, with a dorsal gland; the hyaline margin is barely dentate at 40× magnification. Seed cones are ovoid, (5-)6(-8) mm long by (5-)6(-9) mm wide, brownish, smooth, holding 1-2(-3) seeds, each 3-5 mm long × 3-4 mm wide. Pollen is shed in late spring (Adams 2004).

The species closely resembles J. flaccida and both varieties of J. poblana. Adams and Schwarzbach (2015) present the following key to separate the species in this group:

1.

Seed cones small, (5-)6(-9) mm diam., 1-2(-3) seeds per cone, terminal branch tips erect

 

J. martinezii

1.

Seed cones large, 9-17 mm diam., (4-) 6-10 (-13) seeds per cone, terminal branch tips drooping (hanging)

 

2

2.

Seed cones 9 - 20 mm diam., with (4-) 6-10 (-13) seeds, foliage weeping

 

J. poblana var. poblana

2.

Foliage weeping, branching radially, seed cones brownish-purple, tan-brown

 

3

3.

All leaves decurrent, with free tips, foliage very weeping, bark exfoliating in thin, scaly, plates

 

J. poblana var. decurrens

3.

Leaves decurrent with mostly appressed tips, foliage weeping, bark exfoliating in thick, interlaced stripes

 

J. flaccida

Distribution and Ecology

Mexico: Aguascalientes, Guanajuato, Jalisco, San Luis Potosí, and Veracruz; restricted to small, local populations in rocky areas (Adams et al. 1990, Adams 2004). Grows in montane piñon-juniper woodland, pine-oak forest and woodland, and oak woodland. The altitude range is 1,400-2,400 m according to herbarium collections (Farjon 2013).

This taxon was first recognized and described from a few localities in Jalisco, and even now is only known from six widely-separated locales. Farjon (2013) finds that "a continuing decline is inferred from the fact that there is much clearing for agriculture and grazing that affects junipers, among which are trees of this taxon. Its area of occuancy is here estimated with a grid width of 8 km to account for missing localities, but still falls well under 2,000 km² so it meets the criteria for listing as Vulnerable."

Big tree

Oldest

Dendrochronology

Ethnobotany

Observations

Remarks

Citations

Adams, Robert P. 2004. Junipers of the World: The Genus Juniperus. Trafford Publishing.
Brief versions of the descriptions are available online at www.juniperus.org.

Adams, R.P., J.A. Perez de la Rosa and M. Charzaro. 1990. The leaf oil of Juniperus martinezii Perez de la Rosa and taxonomic status. J. Essential Oil Res. 2:99-104. Available online at juniperus.org.

Adams, R. P., A. E. Schwarzbach and S. Nguyen. 2006. Re-examination of the taxonomy of Juniperus flaccida var. martinezii, and var. poblana (Cupressaceae) Phytologia 88(3):233-241.

Adams, R. P., and A. E. Schwarzbach. 2015. A new, flaccid, decurrent leaf variety of Juniperus poblana from Mexico: J. poblana var. decurrens R. P. Adams & S. González. Phytologia 97(3):152-163.

Farjon, Aljos. 2013. Juniperus flaccida var. poblana. The IUCN Red List of Threatened Species, Version 2015.2. www.iucnredlist.org, accessed 2015.07.28.

Perez de la Rosa, J. A. 1985. Una nueva especies de Juniperus de Mexico. Phytologia 57:81-86.

Silba, J. 1985. A supplement to the international census of the Coniferae. I. Phytologia 58:365-370.

See also

Adams, R. P., and T. A. Zanoni. 2015. The volatile leaf oils of Juniperus flaccida Schltdl., J. martinezii Perez de la Rosa and J. poblana (Mart.) R. P. Adams, re-examined. Phytologia 97(2): 145-151.

Farjon (2005) provides a detailed account, with illustrations (treating it as a variety of J. flaccida).

R.P. Adams' web site, juniperus.org.

Vascular Plant Image Gallery.

Last Modified 2017-12-29