Regularity: Regularly occurring
States or Provinces
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
BLM PHYSIOGRAPHIC REGIONS :
13 Rocky Mountain Piedmont
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. An identification key is available .
Drooping juniper is a native small tree or large shrub that is slow growing and long-lived . Height at maturity usually ranges from 25 to 30 feet (7.6-9.1 m) [37,44]. The national champion tree occurs in Juniper Canyon and is 55 feet (17 m) tall with a crown spread of 35 feet (11 m) and a circumference of 8.5 feet (2.5 m) . Juniperus flaccida var. flaccida reaches a maximum height of 39 feet (12 m) . The most conspicuous character of drooping juniper is its pendant branchlets [33,44]. Young drooping juniper trees usually have a narrow rounded crown. The bark is deeply furrowed and shreds into long strips . The globose, berrylike cone is from 0.25 to 0.5 inch (0.63-1.3 cm) in diameter . Each drooping juniper cone contains from 4 to 12 seeds (usually 6-8) that are 0.12 to 0.25 inch long [33,38,44]. The cones of J. f. var. flaccida contain from 4 to 13 (usually 6-10) seeds . Drooping juniper cones collected by Adams  in the Chisos Mountains averaged 8.35 seeds/cone.
Catalog Number: US 1205343
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Verified from the card file of type specimens
Preparation: Pressed specimen
Collector(s): C. Ehrenberg
Locality: E of Monserrat, Mexico, Central America
- Syntype: Schlechter, F. R. R. 1838. Linnaea. 12: 495.
Habitat and Ecology
Key Plant Community Associations
In the Chisos Mountains, drooping juniper occurs in moist woodlands, pine-oak
(Pinus-Quercus ssp.) woodlands, and oak scrub.
Species other than those listed above with which drooping juniper occurs with include
the tree species Mexican pinyon (P. cembroides), Grave's oak (Q. gravesii), gray
oak (Q. grisea), Emory oak (Q. emoryi), alligator juniper (J.
deppeana), Texas madrone (Arbutus xalapensis), and bigtooth maple
(Acer grandidentatum); the shrub species Wright silktassel (Garrya wrightii),
mountain sage (Salvia regla), fragrant sumac (Rhus
aromatica), Harvard's century plant (Agave havardiana), foothill beargrass (Nolina
erumpens), dwarf oak (Q. intricata), featherplume (Dalea formosa),
and damianita (Chrysactinia mexicana); and the grass species pinyon ricegrass (Piptochaetium
fimbriatum), Mediterranean lovegrass (Eragrostis
barrelieri), bullgrass (Muhlenberis emersleyi), sideoats grama (Bouteloua curtipendula),
and Big Bend bluegrass (Poa strictiramea) [1,10,29,32,45].
Habitat: Rangeland Cover Types
This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):
More info for the term: cover
SRM (RANGELAND) COVER TYPES :
504 Juniper-pinyon pine woodland
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
More info for the term: cover
SAF COVER TYPES :
241 Western live oak
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
KUCHLER  PLANT ASSOCIATIONS:
K031 Oak-juniper woodland
K054 Grama-tobosa prairie
Climate: Where drooping juniper grows in the Chisos Mountains, precipitation ranges from 8.7 to 27 inches (220-680 mm), with most falling from May to October [26,45]. It rarely freezes, and summer temperatures routinely exceed 100 Â°F (40 Â°C) .
Elevation: In the Chisos Mountains, drooping juniper generally is found above 5,000 feet (2,000 m) . In Mexico, it occurs from 4,000 to 8,000 feet (1,000-2,000 m) [3,44]. The elevational range of J. f. var. flaccida in Texas and Mexico is 3,000 to 9,500 feet (900-2,900 m) .
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES40 Desert grasslands
Immediate Effect of Fire
Specific information on the relationship of fire severity and damage to drooping juniper is lacking. Drooping juniper has shreddy bark and volatile leaf oils which probably render it highly flammable. It is probably easily killed by fire.
POSTFIRE REGENERATION STRATEGY :
Tree without adventitious bud/root crown
Fire adaptations: Specific information on the fire ecology of drooping juniper is lacking. Other junipers (Juniperus spp.) are highly vulnerable to fire, and usually occur in large numbers only in fire refugia.
FIRE REGIMES: Fire is a common occurrence where drooping juniper occurs in the Chisos Mountains. Dick-Peddie and Alberico  reported that lightning fires are probably highly localized, and are often confined to single trees. Downed woody fuels are usually scarce, and continuous fine fuels consist of herbs . Using fire scar data, Moir  assessed that fire frequency in the Chisos Mountains ranged from 0.9 to 2.0 fires/century. The research conducted by Moir suggests a mean fire interval for the Chisos Mountains of approximately 70 years [29,30]. Research conducted by Leopold and Krausman  in the Chisos Mountains showed a mean fire interval of 60 years.
The following table provides fire-return intervals for plant communities and ecosystems where drooping juniper is important. For further information, see the FEIS review of the dominant species listed below.
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|desert grasslands||Bouteloua eriopoda and/or Pleuraphis mutica||<35 to <100|
|pinyon-juniper||Pinus-Juniperus spp.||<35 |
|Mexican pinyon||Pinus cembroides||20-70 [30,40]|
|oak-juniper woodland (Southwest)||Quercus-Juniperus spp.||<35 to <200 |
More info for the term: succession
At the time of this review (2007), there is no information on the successional status of drooping juniper. Information pertaining to drooping juniper succession is much needed.
Large seed crops are produced every 2 to 3 years, with light crops produced in intervening years . The widespread distribution of drooping juniper in Mexico is probably partly due to the number of seeds/cone, which is "large" when compared to other junipers .
Pollination: Drooping juniper is pollinated by the wind.
At the time of this review (2007) there is no information relating to drooping juniper seed banking, production, or germination; seedling establishment or growth; or vegetative regeneration. Research on drooping juniper reproduction is sorely needed.
Growth Form (according to Raunkiær Life-form classification)
Fire Management Considerations
Plant Response to Fire
Life History and Behavior
Some researchers report that drooping juniper cones mature in September or October of their second year [37,42,44] and are persistent . However, Flora of North America  reports a 1-year ripening period for drooping juniper.
Molecular Biology and Genetics
Barcode data: Juniperus flaccida
Statistics of barcoding coverage: Juniperus flaccida
Public Records: 2
Specimens with Barcodes: 4
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
This is one of the most widespread of the junipers, ranging almost throughout Mexico and just into Texas across the Rio Grande at Big Bend National Park.Only the variety martinezii is considered to be under threat and is listed as Vulnerable. The other varieties (flaccida and poblana) are Least Concern.
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
Relevance to Humans and Ecosystems
Other uses and values
Importance to Livestock and Wildlife
Very little is known about the importance of drooping juniper to livestock and wildlife. birds and mammals consume drooping juniper's fleshy cones [45,48]. Arizona gray foxes in the Sierra Madres of Chihuahua, Mexico, also eat the cones .
Palatability/nutritional value: No information is available on this topic.
Cover value: No information is available on this topic.
Juniperus flaccida (Weeping Juniper or Mexican Juniper; Native American names include tláscal) is a large shrub or small tree reaching 5-10 m (rarely to 15 m) tall. It is native to central and northern Mexico (from Oaxaca northward) and the extreme southwest of Texas, United States (Brewster County). It grows at moderate altitudes of 800-2,600 m, on dry soils.
The bark is brown, with stringy vertical fissuring. The shoots are strongly pendulous, 1-1.2 mm diameter, and often borne in flattened sprays (the only juniper commonly showing this character). The leaves are arranged in opposite decussate pairs; the adult leaves are scale-like, 2-4 mm long (to 7 mm on lead shoots) and 1-1.5 mm broad. The juvenile leaves (on young seedlings only) are needle-like, 5-10 mm long. The cones are berry-like, 8-20 mm in diameter, green maturing brown, and contain 6-12 seeds (the most seeds per cone of any juniper); they are mature in about 18 months. The male cones are 3-5 mm long, and shed their pollen in spring. It is largely dioecious, producing cones of only one sex on each tree.
There are three varieties, not accepted as distinct by all authorities:
- Juniperus flaccida var. flaccida. Throughout the range of the species. Cones 9-15 mm diameter, with inconspicuous scale margins.
- Juniperus flaccida var. martinezii. Restricted to a small area in Jalisco. Cones 6-8 mm diameter, with inconspicuous scale margins.
- Juniperus flaccida var. poblana. Throughout the southern two thirds of the range of the species. Cones 12-20 mm diameter, with conspicuous scale margins.
|Wikimedia Commons has media related to Juniperus flaccida.|
- Adams, R. P. (2004). Junipers of the World: The genus Juniperus. Trafford Publishing ISBN 1-4120-4250-X
- Gymnosperm Database: Juniperus flaccida
- Flora of North America: Juniperus flaccida
- Conifer Specialist Group (1998). Juniperus flaccida. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 28 July 2006.
Names and Taxonomy
Schlecht. (Cupressaceae) [14,15,20,21,33,37]. There are 3 recognized varieties:
Juniperus flaccida var. flaccida Schlecht. [14,15]
Juniperus flaccida var. martinezii (PÃÂ©rez de la Rosa) Silba
Juniperus flaccida var. poblana Martinez 
Juniperus gigantea Roezl p.p.
Juniperus gracilis Endl. 
Mexican drooping juniper