The olive trees on the west side of campus are some of the oldest trees in Tucson. They were planted just after the University was established in the late 1800s. Robert Forbes was first head of the Agriculture Experiment Station. The mission of the University’s Ag Experiment Station is to evaluate crops for potential success in each area of the country. Forbes was particularly interested in trying fruits and nuts from the Mediterranean lands.

Forbes lived to be over 100 years old and was a familiar fixture on the University campus during his life. Until he died in 1967, he continued his interest in the University, its students, and its research projects. He left all his papers to the Arizona Historical Society.

Some of Forbes’s olives also grace older neighborhoods through Tucson, and a short street where his house stood is named Olive Road. (This house was on the site of the current Center For Creative Photography). Just as importantly, many of the original olives tested on the UA campus survive to this day.

The following passage is from the UA Historic Preservation Plan, adopted by the Arizona Board of Regents in 2006. The full document can be downloaded here. It was written in 2005 by Thomas Brown and Elizabeth Davison.

"It is known from old nursery catalogues that at least 46 varieties of olive were bing offered in California nurseries between 1885 and 1895. The Santa Barbara nurseryman Kinton Stevens, in his 1891 and 1893 catalogues, offered the following varieties of olives: Cucco, Fantoiano (Frantoio, Frantojo), Manzanillo, Mission, Morchiaio, Morinello (Morailo), Nevadillo Blanco, Nostralis, Palazuolo, Picholine, Redding Picholine and Rubra (Caillon).

In his Notes from Assembly Talk, March 1, 1934, Robert Forbes says “On April 1, 1895, they planted a row of olive trees from Santa Barbara on the west side. Those in front of the girls dormitories (along North Campus Drive) I planted later.” It is highly likely the trees mentioned by Dr. Forbes came from Stevens and were some or all of the above varieties. They are Italian, Spanish and French in origin."

In the 1940s, the former Kinton Stevens nursery site in Santa Barbara was bought by Madame Ganna Walska, who continued to enlarge and enhance the gardens (with the help of Stevens’ son Ralph) until she died in 1984 at the age of 97. At that time, the estate - including some century-old olive trees - was made into a public garden, now called Ganna Walska Lotusland.

The Campus Arboretum was searching for information about the specific varieties, and we were fascinated with the idea that the Kinton Stevens offerings in 1890 were advertised as rooted cuttings from trees on his property. Put another way, we thought Lotusland might still have the parents to our olives. So we did some investigating.

After contacting staff at Lotusland in 2006, we arranged to have their olives tested for any genetic linkage with the UA olives. To accomplish this, the 35 olive trees running north-south along the University’s Olive Walk were put through DNA analysis at the UC Davis Olive Center.

Graduate student Jolie Goldenetz traveled to Santa Barbara to gather Lotusland olive branches and took them, along with the UA plant material, to UC Davis for analysis as to variety and relationship to each other. Support for Jolie’s work came from a generous donor. All the olive cuttings were rooted in the UC Davis greenhouses, and new shoot tissue was used for the analysis.

Results confirm that some olive varieties sold by Kinton Stevens in 1890 are here on campus. The 35 UA olives running north and south on Olive Walk, just inside the Main Gate, include the following varieties, all verified by the UC Davis database: Mission, Chemlali, Mavrelia, and Manzanillo.

However, the Lotusland samples don’t match genetically with the 35 tested UA olives. What does this mean? Essentially it means that the olives that have survived until 2006 at Lotusland were not the stock from which the UA olives were originally cloned.

Furthermore, the UC Davis database of California olive varieties does not contain all the olives originally sold by Kinton Stevens. This means that many varieties of olives originally sold by Stevens include some good survivors (Mission for example), but also some that never were suited to the California conditions (and are not in UC Davis’s listing).

On the other hand, we can say which of Stevens’ varieties have survived in Tucson: Mission, Mevrelia (Morailo), and Manzanillo. Likewise, we know that a couple of the existing UA trees are not available in California at this time. So - they were uniquely suited to Arizona, where they have graced the campus for over 100 years. And information about suitability is the goal of every variety trial - just what Robert Forbes was working on.

This selection written by Thomas Brown comes from p. 29 in the Preservation Plan –


This statement describes suitability of trees for both beauty and science – just what the Campus Arboretum is working on.