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I’ve never seen a mesquite tree I didn’t like.
At least, that seems to have been J. Frank Dobie’s thought as he wrote:
“I could ask for no better monument over my grave than a good mesquite tree, its roots down deep like those of people who belong to the soil, its hardy branches, leaves and fruit holding memories of the soil….” (Dallas Morning News, Feb. 9, 1941, p. 12).
My name is Dr. J. Kevin Hanselka, and I am an archeologist in the Archeological Studies Branch of the Texas Department of Transportation (TxDOT). My field of specialization within archeology is paleoethnobotany, or the study of the interrelations between past human beings and the botanical world. This includes anything from the cultural preference and use of plants for food, fuel, fiber or construction, to the interpretation of archeological plant remains in the reconstruction of ancient environments.
At TxDOT I am presently conducting an ongoing study that potentially will clarify ancient rainfall regimes, which of course benefitted, constrained, and otherwise influenced indigenous cultures across Texas. I am inviting interested members of the Native Plant Society of Texas to participate and contribute to this research.
Love them or hate them, mesquite trees have long been a source of fuel, food, shelter, tools and dye, among a great many other things to folks in Texas, the Southwest, and Mexico. This fact, as well as the high frequency of mesquite remains on archeological sites across Texas and elsewhere, makes them a valuable subject for archeological study.
I’m presently compiling a collection of modern mesquite wood for comparison to ancient mesquite charcoal recovered from archeological contexts during excavation. The purpose of this project is to build a baseline dataset for the interpretation of general rainfall regimes prevalent at the time of archeological site occupations (or more specifically during the lives of the plants that produced the ancient wood). The technical aspects of the project are given in more detail below.
I’d like to ask a favor of those of you who occasionally run across mesquite trees and shrubs on your land or while in the field: Whenever you encounter mesquite, please take a few minutes to collect a sample to contribute to this growing comparative collection. (My co-workers at TxDOT will be supplying me with samples from within our right-of-way in various parts of the state where mesquite grows.)
If you wish to contribute a sample, at the time of your collection you will need to have at hand a camera (or camera phone), GPS unit (or a smartphone with an app that gives GPS location coordinates), and a pencil and paper to jot down a few notes. This is to ensure we have adequate contextual information for the specimen to be useful. Please adopt the following protocols for collecting modern mesquite reference specimens:
- Please respect others’ property; if the land is not your own, make sure that you have the owner’s permission to collect a sample, and do not collect from public property unless authorized to do so.
- Please take care not to disturb any nesting birds or other wildlife; leave as little impact on the natural environment as possible.
- I will only need one specimen from any given location. Stem fragments in good condition between 1.5 and 3 inches in diameter, at least 3 inches long, will be sufficient.
- Photograph the whole plant and its setting, and take note of the setting (e.g., landform, etc.).
- Record the date collected and the coordinates of the location from which the sample was collected (UTM, Zone 14).
- Please mail the sample to Kevin Hanselka, Environmental Affairs Division, Texas Department of Transportation, 125 E. 11th Street, Austin, TX 78701. Photographs, coordinates and setting notes can be emailed in.
- If you have any additional questions, please feel free to contact me at (512) 416-2639 or Kevin.Hanselka@txdot.gov.
Thank you in advance for any assistance!
If you’d like a more technical description of my research project, please read on.
Ecologically Diagnostic Xylem Analysis (EDXA) of Mesquite Wood Charcoal in Texas
I’m compiling a collection of modern mesquite wood for comparison to ancient mesquite charcoal recovered from archeological contexts during excavation. The purpose of this project is to build a baseline dataset for the interpretation of general rainfall regimes prevalent at the time of archeological site occupations (or more specifically during the lives of the plants that produced the ancient wood).
Wood anatomy can vary within the basic pattern of a species as a reaction to local environmental conditions. Recent studies in South Africa have shown that some tree species demonstrate predictable changes in the density and diameter of water transport vessels in their wood according to changes in rainfall regime. This approach is known as Ecologically Diagnostic Xylem Analysis (EDXA). Dr. Phil Dering pioneered EDXA in Texas using mesquite, based on modern reference collections obtained from different parts of the state under varying rainfall regimes. In theory, the general moisture regime in effect during the growth cycle of archeologically derived mesquite can be inferred through morphometric comparison of anatomical features between the archeological specimens and experimentally burned modern wood that grew under known moisture regimes.
My goal is to expand and continue building on this research. The first step is to amass larger collections of modern mesquite from widely dispersed areas and settings across Texas. This modern reference collection will be a baseline dataset against which archaeological mesquite wood charcoal will be compared. While this work clearly has implications for paleoenvironmental reconstruction at the site level, in the long term, as the analysis is applied to archeological sites of different ages across wider areas, broader temporal and regional moisture patterns will potentially emerge.
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