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Wednesday - March 12, 2008

From: Moody , TX
Region: Southwest
Topic: Trees
Title: Differences between smooth bark and rough bark Arizona cypress
Answered by: Nan Hampton


What is the difference between smooth bark Arizona Cypress and rough bark Arizona Cypress in terms of tree growth, form, foliage, etc.? Will one grow better than the other in the Waco area?


It is difficult to even pin down what botanical name applies to smooth bark Arizona cypress and/or rough bark Arizona cypress. Plant taxonomists have now lumped them together under one species, Cupressus arizonica (Arizona cypress). You can read in the Gymnosperm Database that there has been great controversy among plant taxonomists about whether rough bark cypress (once named Cupressus arizonica) and smooth bark cypress (once named Cupressus glabra) are two completely different species, different subspecies or different varieties of the same species. The current Integrated Taxonomic Information System (ITIS), which is the authority for the USDA Plants Database, lists these accepted names: Cupressus arizonica (Arizona cypress, Arizona smooth cypress, Cuyamaca cypress, and Piute cypress), Cupressus arizonica ssp. arizonica (Arizona smooth cypress), Cupressus arizonica ssp. nevadensis (Piute cypress), and Cupressus arizonica ssp. stephensonii (Cuyamaca cypress). ITIS doesn't give any of these subspecies the common name of rough bark Arizona cypress.

Here are comments under C. arizonica in the Flora of North America about bark texture:

"Bark texture and foliage features have been used to distinguish geographic varieties or segregate species. Although bark texture may be consistent within populations, over the species as a whole there is complete intergradation between smooth and fibrous barks. Various forms are commonly cultivated and sometimes persistent in the southern United States."

Additionally, from the Gymnosperm Database:

"Certain authors have noted that the morphological differences between the species are for the most part related to their differing ecological settings (e.g., more waxy cuticles in the more desert-adapted groups, serotinous cones in populations experiencing frequent fire)."

The bottom line is that, not only is it difficult to come up with agreement on exactly which tree is which, but any differences between the trees may be due to environmental factors. So, I'm afraid we can't come up with the facts you are asking for about the two.

Will C. arizonica grow well in McClellan County, Texas? Perhaps it will grow, but I can't be sure how well. According to the map of the Vegetation Regions of Texas, McClellan County is mainly in the Blackland Prairies with the western edge considered to be in Cross Timbers and Plains. The distribution of C. arizonica in Texas is shown by the USDA Plants Database to be in only two counties, Brewster County in the Trans-Pecos/Big Bend area of west Texas and Taylor County in a northern pocket of the Edwards Plateau surrounded by the Rolling Plains. There are differences in climate, elevation, land form and soils between these Vegetational Regions of Texas.

Here is more information about C. arizonica from the University of Arizona Pima County Cooperative Extension and from the US Forest Service.


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