Juniperus deppeana (Alligator juniper) description

Tree (var. deppeana) in habitat, Sedona, AZ [C.J. Earle, 1987.12.27].

Distribution of the varieties of J. deppeana. Adapted from Adams and Schwarzbach (2006).

Stand of J. deppeana var. deppeana in southern Puebla [C.J. Earle, 2005.02.10].

Bark on the tree shown above, about 50 cm dbh [C.J. Earle, 2005.02.10].

Sectioned cone collected in Durango [C.J. Earle, 2007.02.10].

Detail of twig and foliage of var. deppeana [C.J. Earle, 2007.02.10].

Detail of berries, twig and foliage of var. deppeana [C.J. Earle, 2007.02.10].

Trees of var. robusta at km 154 on the Durango-Mazatlan highway [C.J. Earle, 2007.02.10].

Detail of twig and foliage of var. robusta collected near the J. blancoi type locality south of El Salto, Durango [C.J. Earle, 2007.02.10].

Juniperus deppeana

Steudel 1841

Common names

Alligator juniper (Elmore and Janish 1976), mountain, thickbark, oak-barked, or checker-barked cedar (Peattie 1950), cedro, cedro chino [in Puebla], sabino, táscate [in Chihuahua and Durango], tláscal or tláxcal [in Hidalgo], huata, agoriza [in Sonora], aborí, aorí, awarí, aworíki, kawarí, koarí, petcalawa, waaka [Tarahumar people of Chihuahua], ga'a [Pima people of Chihuahua] (Zanoni and Adams 1979).

Taxonomic notes

Four varieties according to Adams and Schwarzbach (2006), who base their analysis on DNA sequencing data using nrDNA and trnC-trnD sequences:

Var. deppeana (includes formae elongata, sperryi and zacatecensis)
Var. gamboana
Var. patoniana
Var. robusta

The remainder of this page describes the species, with a key to the varieties; see the links above for detail on varieties deppeana and gamboana.

Description

"Trees dioecious, to 10-15(-30) m, single-stemmed; crown rounded. Bark brown, exfoliating in rectangular plates (rarely in thin strips in f. sperryi, but then branchlets flaccid), that of small branchlets (5-10 mm diam.) smooth, that of larger branchlets exfoliating in plates. Branches spreading to ascending; branchlets erect, rarely flaccid, 3-4-sided in cross section, ca. 2/3 or less as wide as length of scalelike leaves. Leaves green, but sometimes appearing silvery when glaucous, abaxial gland ovate to elliptic, conspicuous, exudate absent, margins denticulate (at 20´); whip leaves 3-6 mm, not glaucous adaxially; scalelike leaves 1-2 mm, not overlapping, keeled, apex acute to mucronate, appressed. Seed cones maturing in 2 years, of 2 distinct sizes, with straight to curved peduncle, globose, 8-15 mm, reddish tan to dark reddish brown, glaucous, fibrous to obscurely woody, with 1-7 seeds. Seeds 6-9 mm" (Adams 1993, Adams and Schwarzbach 2006).

Adams and Schwarzbach (2006) provide the following key to the varieties and formae of J. deppeana:

1a.	Terminal whips long (15 - 30 cm) and pendulous, all (or nearly all) leaves on adult plants juvenile (decurrent, or whip type)	var. deppeana f. elongata
1b.	Terminal whips short (5 - 10 cm) and not pendulous, all leaves on adult plants scale-like (except on new growth where whip leaves occur)	2
2a.	Seed cones small (5-8 mm diam.), with soft pulp and 1(2) seeds, reddish brown with a light bloom, Chiapas, Mexico and adjacent Guatemala	var. gamboana
2b.	Seed cones large (8-20 mm diam.), woody and (1) 2 - 7 seeds, brown, reddish brown, or purplish with little to copious bloom, from central Mexico northward to Arizona and New Mexico in USA.	3
3a.	Stem bark longitudinally furrowed into long, interconnected strips, terminal whip branches often flaccid and pendulous	var. deppeana f. sperryi
3b.	Stem bark in quadrangular plates or in longitudinal strips (occasionally interconnected, if exfoliating in strips, then foliage not weeping), occasionally quadrangular plates at the trunk base, terminal whip branches ascending to erect	4
4a.	Stem bark exfoliating in longitudinal strips (occasionally interconnected) or with plates near the trunk base	var. patoniana
4b.	Stem bark exfoliating in square or oblong quadrangular plates, not in strips.	5
5a.	Trees with a strong central axis, no major side branches, crown pyramidal, and open as in Cupressus, often with 2 (3-4) trunks rising at (or below) ground level	var. robusta
5b.	Trees with round crown, branching at 1-4 m to produce irregular, round crown, usually with a single trunk	6
6a.	Mature female cones larger, 10-20 mm. diam., heavy bloom (glaucous waxy coating) on cone surface causes cone to appear white; shrub/small round topped tree (to 8m)	var. deppeana f. zacatecensis
6b.	Mature female cones smaller, 8-15 mm diam., glaucous or not, if glaucous not appearing as white, small to large trees	var. deppeana

Range

USA: Arizona, New Mexico, Texas; Mexico: Aguascalientes, Chiapas, Chihuahua, Coahuila, Durango, Hidalgo, Jalisco, México, Michoacán, Nuevo León, Puebla, San Luis Potosí, Sonora, Tamaulipas, Tlaxcala, Veracruz, and Zacatecas; Guatemala; at 1500-2900 m (Zanoni and Adams 1979, Adams 1993). See also Thompson et al. 1999.

The conservation status of this species is variable. Overall it is "lower risk," but var. robusta and var. deppeana f. zacatecensis are "vulnerable," and var. deppeana f. sperryi is "critically endangered" (IUCN 2008).

Big tree

See var. deppeana.

Oldest

Dendrochronology

Ethnobotany

Observations

I found numerous fine examples of var. robusta west of El Salto along the Durango-Mazatlan highway in Durango. See also the links to varieties deppeana and gamboana.