Juniperus deppeana (alligator juniper) description

Juniperus deppeana

Steudel 1840

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 Hesperocyparis, 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

Distribution and Ecology

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). 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.

Map of the the distribution of Juniperus deppeana, with undifferentiated J. deppeana shown in red, var. deppeana in orange, var. gamboana in green, var. patoniana in yellow, var. robusta in lavender, and var. zacatecensis in blue. Map based on GBIF Occurrence Download https://doi.org/10.15468/dl.d23zc3 and GBIF Occurrence Download https://doi.org/10.15468/dl.6fdugj, both retrieved 2023.08.06; data limited to occurrences with coordinate uncertainty <10 km and trimmed to eliminate extralimital occurrences, likely misidentifications, and location duplicates within a nearest-neighbor distance of 1 km. See figure at right for approximate distribution of other varieties.

The conservation status of this species is variable. Farjon (2013, accessed 2022.03.20), reporting a 2011 conservation assessment, provides a "Least Concern" ranking for the type variety and var. pachyphlaea (which is here treated as synonymous with var. deppeana). Var. robusta is ranked "Vulnerable". Var. zacatecensis is "Endangered" and var. sperryi "Critically Endangered" (note that both vars. are here reduced to formae of the type variety, per the findings of Adams and Schwarzbach (2006)). Farjon does not recognize var. patoniana, treating it as synonymous with var. robusta. He elevates var. gamboana to species rank, designating it "Endangered."

Remarkable Specimens

The largest reported tree is in var. deppeana.

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.

Remarks

The epithet honors Ferdinand Deppe (1794-1861), a German naturalist, explorer and painter, who collected plants in Mexico with Scheide in 1828-29.

Citations

Adams, Robert P. 1993. Juniperus. Flora of North America Editorial Committee (eds.): Flora of North America North of Mexico, Vol. 2. Oxford University Press. This document is available online. Go to http://www.efloras.org, click on "Flora of North America," and search for "Juniperus."

Adams, Robert P. and Andrea E. Schwarzbach. 2006. Infraspecific adjustments in Juniperus deppeana (Cupressaceae). Phytologia 88(3):227-232.

Steudel, E. G. von. 1840. Nomenclator botanicus enumerans ordine alphabetico nomina atque synonyma... Ed. 2, V. 1. Stuttgart: Tubingen (p. 835).