In Search of the Florida Sour Orange Lineage

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Dr. Bob Hartman, CEO of Classic Caladiums, spent his early years in Miami. When he was a young teen, his father purchased 20 acres in Palmdale, FL. The south side of the property was comprised of densely wooded hammock. The hammock doubled as Hartman’s playground and adventure land. Consequently, he knew the property like the back of his hand. Curiously, the hammock also was home to a range of citrus trees.

Some were scion seedlings, likely volunteers distributed by animals. Others were rootstocks that had recovered after devastating freezes had settled into the low-lying areas of Glades County. There also were a number of surviving grafted citrus trees on the site, with bud unions well above the height of an average adult. It was all too coincidental. The citrus planting had clearly been a grove. But what was its purpose, why was it in Palmdale, and why would someone bud trees eight feet off the ground?

Hartman recalls an elderly man paying an impromptu visit to the Palmdale property when he was a teenager. This would have been in the early to mid-1960s. The visitor informed the Hartmans that the property had once been a government citrus research site in the early part of the last century. The visitor’s recollection was that the main body of the grove was planted around 1907.

The reason offered for the height of the grafts was two-fold. First, it kept the scion fruit out of the reach of range cattle. Second, the hammock was known to be infested with rattlesnakes, so the grafting was done from horseback. Hartman has never been able to verify whether the elderly visitor’s story is true, and a few quick calls to USDA’s Horticultural Research Laboratory in Fort Pierce provided no evidence that it was ever a USDA site.

We have been able to uncover some early articles indicating the UF Florida Agricultural Experiment Station may have had some tie to Palmdale, but it mostly remains a curious and unanswered question.

Hartman’s career later took him to Chicago, but he returned to Florida in 1977 where he joined his parents, John and Audrey, who maintained a small ornamental potted plant business. Hartman and his wife Linda established a tissue culture and micropropagation company on the site, producing gerbera daisies, caladiums, bromeliads, and a host of other ornamental plants.

Beth Lamb, who now manages a citrus tissue culture laboratory and micro-propagation facility for Phillip Rucks Citrus Nursery (Frostproof) worked approximately 10 years in the labs on the Palmdale property. She worked for Hartman part of the time and for subsequent owners after the property was sold in 1984.

Throughout this time, she became intimately familiar with the unique plant species and citrus trees resident in the oak hammock. She recently shared this information with Rucks who, in turn, passed the story on to me. Lamb offered to contact Hartman and Casa Flora (the current owner) and ask permission to explore the hammock. Hartman offered to be the guide, and Casa Flora graciously granted access. The team visited the property in mid-February 2020.

During the drive south to Palmdale, Rucks shared his primary interest in the property. He explained that several sour orange lines are currently used in Florida. One is the sour orange we think of as the old Florida line. He believes there are some physical characteristics and performance traits of the current Florida sour orange that differ from the early descriptions of the variety. He further explained that Florida has imported significant quantities of sour orange seed from California over the years.

The California line is known to be from Brazil and was chosen for its vigor, but it differs in other ways from the old Florida sour line. He thought that it would be interesting to collect some seed from the remaining sour orange tree sprouts in the hammock, or at the very least, from volunteer sour orange seedlings that would have emanated from the same line. These can be grown out and compared. They also can be introduced into tissue culture as a means of preservation and broader distribution. It will be interesting to learn how the DNA fingerprint of the hammock material compares to the sour lines currently used in Florida.

The trip was a success. Sour orange fruit samples were collected from the hammock. It was like getting a shipment of fruit from 1907. While there, the team also found rough lemon fruit, a tangor-like fruit similar to Temple, Duncan Grapefruit, and a few other fruit that appear to be natural hybrids of what was originally planted in the grove.

Rucks and Lamb will start the process of evaluating and comparing the lines. Who knows, this may result in the discovery of a sour orange line that provides superior fruit quality and/or better protection against pests and diseases currently challenging our growers. Then again, we may find that though they appear to be different, they behave very much like what we have. Stay tuned. We know one thing — it was time well spent.