The St. John Cathedral Oak is located in Lafayette, Louisiana, on the grounds of the Cathedral of St. John the Evangelist. It is currently the second Vice President and a founding member of the Live Oak Society, an organization whose members are all live oaks, with the exception of one human, who serves as “Chairman” and maintains the roster of past, present, and future tree members, as they are registered. Dr. Edwin Lewis Stephens, first President of Southwestern Louisiana Institute (now the University of Louisiana at Lafayette) proposed in a 1934 article titled, “I Saw in Louisiana a Live Oak Growing”  that a society of the largest and oldest live oaks (Quercus virginiana) in Louisiana be created to identify and protect these trees for future generations to enjoy. It was Dr. Stephens’ vision that the association’s members would be oaks whose size and age made them cultural and natural resources worth recognition and preservation.
Registration & Measurements: Dr. Stephens’ article listed 43 live oaks that he proposed for charter membership in the order of their size (girth or circumference measured at four feet from the ground), beginning with the largest, the Locke Breaux Oak (now deceased), at 35 feet in girth. The large oak on the grounds of the Cathedral of St. John the Evangelist was well-known to Dr. Stephens, and he listed it as the 33rd largest tree of his acquaintance:
“Thirty-three, Cathedral Oak, Lafayette, 19 feet (measured for State Superintendent Francis G. Blair, of Illinois, who published some account of it in his annual Arbor and Bird Days book for 1929).”
The Cathedral Oak is also commonly known today as the St. John Cathedral Oak. It is #65 in the Live Oak Society records. A second measurement of 26 feet, 7 inches was entered in the Society’s records in 2002 and was used to determine the oak’s place among the Live Oak Society’s list of “Top 100” trees from 2003. Additional measurements have been recorded in recent years, as the interest in documenting and measuring large trees, and live oaks, in particular, has increased. The cathedral’s website reports a measurement made on May 30, 2008, by Jim Foret, a local arborist, and teacher at the University of Louisiana, Lafayette:
“The near five-century-old tree measures 9 feet in diameter, with a circumference of 28 feet 8 inches; it stands approximately 126 high with a spread of 210 feet across.”
Note: Jim Foret and I re-measured the Cathedral Oak on Saturday, May 30, 2015, and it’s now 29′ 6″ in circumference. The two photos above were made that day.
By any account, this is a massive and sprawling tree, with an unusual twisting and ropy trunk. It is also difficult to photograph and retain a sense of its size and shape because of the long, low branches that jut sharply from the trunk at several angles.
Age & History: The measurements of older live oaks, as well as other trees species, are of interest to arborists, scientists, and conservationists, as they study rates and conditions of growth. Most methods of age estimation rely on various formulas that translate the tree’s girth or diameter into years to avoid using more invasive techniques, such as coring, that may cause the trees harm. The Live Oak Society’s initial criteria for membership was based on an oak having a girth of at least 17 feet, which Dr. Stephen’s estimated would place the tree’s age at approximately 100+ years (today, the Society says that 16 feet of girth qualifies an oak as a centenarian tree). Dr. Stephens recognized, however, that varying habitats produced different growth rates and tree sizes:
“Therefore we may infer that close-grown live oaks may be several hundred years old, and still much smaller in girth than these we have listed. So, there should be a by-law for this Live Oak Association, admitting members of smaller girth than 17 feet, when sufficient evidence appears for the age of not less than a hundred years.”
Since 1934, the Live Oak Society has added a “junior league” category and allows for the registration of live oaks with a minimum of 8 feet in girth. This has resulted in a significant increase in the Society’s membership, which now includes more than 8700 live oaks in 14 states (as of April 2019).
The title of “centenarian” is still reserved to those trees estimated to be at least 100 years old. It is interesting to note that in 1934, at 19 feet, the St. John Cathedral Oak would have been approximately 150 years old, using Dr. Stephens’ method of age estimation, though the church estimates the tree’s age as much older. The existence of this ancient oak in 1821 and its prominent size is believed to have been a primary reason for the selection of the site on which the first Cathedral of St. John the Evangelist was built:
“Many speculate that our first pastor (Michel Bernard Barriere) selected the specific plot of land for the church parish due to the grand oak tree, which would have been 275 years old at that time (1821).”
The information above illustrates how difficult it can be to arrive at an accurate age estimate for old oaks. If the Cathedral oak was 275 years old in 1821, then it would have been almost 400 years in 1934 instead of the 150-year estimate that Dr. Stephens’ girth measurement of 19 feet might suggest. The average oak’s growth rate is estimated to be most rapid during the first 75 to 100 years, slower during the next 75 to 100, and then even slower after that point. The girth growth logically would slow as the tree matures and its system extends to support multiple branches (some that are nearly as large as the trunk itself) and wide canopy spreads. The difference in girth noted between 1934 and 2002 in the Cathedral oak could also be a result of the variations in girth that can occur when one measures 6 inches higher or lower up or down the tree’s trunk. Many older oaks have massive limbs or root balls within this 4 to 4.5-foot range that adds significantly to its girth. The Live Oak Society President, the Seven Sisters Oak is estimated to be around 1200 years of age. The Angel Oak near Charleston, South Carolina is estimated to be between 500 and 1500 years old (500 years is a more realistic guess).
Future Generations: Dr. Stephens made provision for future generations of live oaks to be grown from the hardy stock of the Live Oak Society’s registered trees. The Society’s original by-laws stated that “annual dues” of 25 acorns be collected from each oak member. These were to be planted on the Southwestern Institute farm (near Lafayette). Although the practice has since been discontinued, many of the acorns planted as a result of his efforts are now mature oaks today, many growing on the grounds of the University of Louisiana at Lafayette. The St. John Cathedral Oak, and two other venerable members of the Live Oak Society have also donated their acorns to national reforestation efforts, as noted by Ethelyn Orso, in her informative book, Louisiana Live Oak Lore:
“Acorns from famous and historic Louisiana live oaks were collected in 1990 to be used in a reforestation program sponsored by the American Forestry Association. Trees chosen for the project included the Seven Sisters Oak, the Oak Alley Plantation trees, and the St. John Cathedral Oak. The acorns were planted and the resulting seedlings were transported to other states to create America’s Historic Forests. Each new forest will be at least 1,000 acres and will include more than 500,000 trees. Such a project could also be undertaken in parts of Louisiana where great stands of live oaks once stood.”
 Dr. Edwin Lewis Stephens, President, Southwestern Louisiana Institute, “I Saw in Louisiana a Live Oak Growing”, Louisiana Conservation Review Vol. IV, No. 2 (April 1934), 16-23.
 http://www.saintjohncathedral.org/Our_Church.html  Ethelyn G. Orso, Louisiana Live Oak Lore (Lafayette, Louisiana: The Center for Louisiana Studies, University of Southwestern Louisiana, 1992), 20.