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Tree of Juniperus flaccida var. poblana, collected along the toll road ca. 130 km N of Oaxaca [R. Van Pelt, 2005.02.08].

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Scale foliage and pollen cones from the tree shown above [C.J. Earle, 2005.02.08].

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Branchlet from the tree shown above [C.J. Earle, 2005.02.08].

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Bark of the tree shown above, about 50 cm dbh [C.J. Earle, 2005.02.08].

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Sapling growing near the tree shown above. It is about 60 cm tall, has been heavily browsed, and retains acicular foliage [R. Van Pelt, 2005.02.08].

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Woodland of deciduous oak (Quercus sp.) and J. flaccida var. poblana along the toll road about 50 km N of Oaxaca [R. Van Pelt, 2005.02.11].

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Cones on a tree near Zaragoza, Nuevo Leon [Jeff Bisbee, 2014.09].

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A tree about 8 m tall [C.J. Earle, 2007.02.16].

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Growing on a N-facing slope [C.J. Earle, 2007.02.16].

 

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Conservation status

Juniperus flaccida

Schlechtendal 1838

Common names

Drooping juniper, drooping cedar (Peattie 1950), cedro, cedro liso, cipres, enebro, sabino, tlascal, tascate, Mexican drooping juniper (Zanoni and Adams 1979), weeping juniper (Adams 2004).

Taxonomic notes

Three varieties:

Synonymy for Juniperus flaccida var. flaccida (Adams 2004):

Synonymy for Juniperus flaccida var. martinezii (Adams 2004):

Synonymy for Juniperus flaccida var. poblana (Adams 2004):

Description

Dioecious trees or shrubs up to 12 m tall, trunks forking 1-2 m above base, crown globose. Bark cinnamon to red-brown or gray to red-brown, exfoliating in broad interlaced fibrous strips. Bark on branchlets (5-10 mm diameter) smooth, that on larger branches exfoliating in wide strips or plates. Branches drooping; branchlets somewhat pendulous, 3-4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves green, abaxial gland variable, elongate, conspicuous, exudate absent, margins appearing entire at 20× but with irregular teeth at 40×; decurrent leaves 4-6 mm, not glaucous adaxially; scale leaves 1.5-2 mm, overlapping by 1/4-1/5 their length, apex rounded to acuminate, spreading. Seed cones maturing in 1 year, of similar size, with straight to curved peduncles, globose, 5-20 mm, tan-brown to brownish purple when mature, glaucous, obscurely woody, with 1-13 seeds. Seeds 5-6 mm long (Zanoni and Adams 1979, Adams 1993, Adams 2004).

Adams (2004) provides the following key to the varieties:

1a.

Seed cones 5 - 9 mm diam., with 1 - 2 (3) seeds, foliage scarcely weeping

 

var. martinezii

1b.

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

 

2

2a.

Scale leaves on ultimate twigs obtuse, scale leaf tips appressed, mature seed cones usually smooth (or with horn-like protuberances from the enlarged cone-scale tips)

 

var. flaccida

2b.

Scale leaves on ultimate twigs acute and sharp, scale leaf tips divergent, mature seed cones usually showing suture lines from the fusion of cone-scales

 

var. poblana

Var. flaccida is a tree up to 12 m tall, with the trunk usually forking at 1-2 m. Bark is cinnamon red-brown or gray red-brown, exfoliating in broad interlaced fibrous strips. Branches spread to form a globular crown. Branchlets are drooping, flaccid. Leaves include both decurrent and scale types, the scale leaves often appearing somewhat decurrent, 1.5-2 mm long, opposite, narrowly ovate, acuminate. Both decurrent and scale-leaf margins appear entire under 20× magnification, but have irregular teeth at 40×. Seed cones are (4-)6-10(-13) seeded, tan-brown to brown-purple, glaucous, 9-20 mm in diameter. Seeds are 5-6 mm long. Pollen is shed late winter-early spring (Adams 2004).

Var. martinezii is a 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).

Var. poblana is a tree up to 8 m tall, usually with a forked trunk and globose crown. Bark is brown, exfoliating in wide strips. Branches are erect, but flaccid at the tips, so that the tree retains a "drooping" character in comparison with other Mexican junipers. Both scale and decurrent leaves are conspicuous, the scale leaves on ultimate twigs with sharp, acute, divergent tips (appearing decurrent). Seed cones are glaucous, blue-brown, 9-12 mm in diameter; the mature cones usually show suture lines from fusion of the cone-scales, thus resembling a soccer ball. There are (4-)6-10(-13) seeds per cone. Pollen is shed in the spring (Adams 2004).

Distribution and Ecology

Mexico: Aguascalientes, Chihuahua, Coahuila, Distrito Federal, Durango, Guanajuato, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Nuevo León, Oaxaca, Puebla, Queretaro, San Luis Potosí, Sonora, Tamaulipas, Veracruz, and Zacatecas; and USA: Texas (Zanoni and Adams 1979). Hardy to Zone 8 (cold hardiness limit between -12.1°C and -6.7°C) (Bannister and Neuner 2001).

Distribution data from USGS (1999).

Var. flaccida, the most common, occurs in Mexico: Chihuahua, Coahuila, Distrito Federal, Durango, Guanajuato, Guerrero, Hidalgo, Jalisco, México, Michoacán, Morelos, Nuevo León, Oaxaca, Puebla, Queretaro, San Luis Potosí, Sonora, Tamaulipas, and Zacatecas; and USA: Texas (Zanoni and Adams 1979), where it grows in the Chisos Mtns. at 1830 to 2440 m (Peattie 1950). See also Thompson et al. 1999.

Var. martinezii is restricted to small, local populations in Mexico: Aguascalientes, Guanajuato, Jalisco, San Luis Potosí, and Veracruz (Adams et al. 1990).

Var. poblana occurs in southern Mexico. Zanoni and Adams (1979) map its occurrence at 1200-2300 m elevation in Jalisco, Hidalgo, México, Moreles, Distrito Federal, Puebla, Guerrero and Oaxaca, and infer its presence in intervening areas. It lives on dry, calcareous slopes, in pure stands or in mixed forests, at 1200-2300 m elevation. It is not nearly as common as its congeners in the western United States, but is usually abundant where it occurs.

Big tree

A tree with diameter 82 cm, height 17 m, and crown spread 11 m, is located in Big Bend National Park, Texas (American Forests 1996). It is quite possible that larger specimens occur in Mexico, but I have no information on this.

Oldest

Dendrochronology

Ethnobotany

Observations

Remarks

Citations

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.

See also

Farjon (2005) provides a detailed account, with illustrations.

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

Vascular Plant Image Gallery.

Last Modified 2014-12-05