The Handbook on Oleanders

Franklin D.Roosevelt

10

"Little flower- but if I could understand

What you are, root and all, and all in all,

I should Know what God and man is."

Alfred Lord Tennyson

Oleander Research

Plant research is often highly technical requiring sophisticated laboratory facilities, years of background and training in botanical sciences, and many more years of painstaking experimentation and documentation. Current research is focused on the various cardenolide glycosides and other constituents in oleanders and their pharmaceutical applications, especially with regard to cancer. Known historically to have been used to treat cancerous ulcers and external carcinomas, extensive research was begun on the oleander in the late 1950's by Turkovic and Jager et al., continued in the 1960's by Janiak et al., in the 1970's and 1980's by Yamauchi, and by Tittel and Wagner in 1981.

The field of taxonomy is also extremely complex involving many aspects of botanical study from plant physiology and phytochemistry to herbarium specimens and field trials. For more details on the subject, we recommend Leeuwenberg's Series of revisions of the Apocynaceae XII, 1984 and notes on Nerium L., F.J.J. Pagen's completion of the revision under Leeuwenberg's supervision, and Pagen's book Oleanders, Nerium L. and the oleander cultivars (1987). Both are published at Wageningen Agricultural University, The Netherlands, and thoroughly cover the taxonomic aspects of the genus. ,

Our primary focus is on research relating to ornamental applications, i.e. greater cold hardiness, hybridization leading to new colors, more dwarf and compact plants, different fragrances, etc. We hope all gardeners will become "researchers" by collecting and photographing the best varieties, and will encourage nurserymen to propagate them so a greater selection can be made available to the gardening public. One of the most important scientific projects that could be undertaken and should receive grant consideration is a "key" to the named cultivars throughout the world. This would clarify the vast confusion that exists with plants coming from one area of the world and being renamed in another. Although it would be a costly and timeonsuming project, possible only with the aid of gene mapping, similar research is currently being done on other plant species to establish irrefutable documentation.Bob Newding had this to say on the subject of nomenclature:

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Well, I'm a trained biologist so there's a certain psyche that biologists have about things. If you collect one you want the next one, and the next one, and pretty soon you want to complete your collection. After visiting with people who knew the nomenclature I started going around trying to name the ones that I saw and oftentimes I'd make mistakes as I would see something that didn't look the same as it did a month earlier. I found out that oleander blooms change their characteristics as the year goes by due to exposure to heat, wind, etc. Some of the flowers and some varieties simply change color from the time they first bloom until they finish blooming at the end of the summer. The 'Franklin Delano Roosevelt', for instance, starts out as a salmon pink and it goes almost to an orange, and at the end of the summer it's copper colored. So, unless you see it at different times, you'll think it's a different plant.

The Turners in Corpus Christi are presently concentrating their efforts on creating a true lavender or purple oleander as well as developing a new category which they have tentatively entitled "miniature" or "toy." Plants in this group would not exceed 2 feet in height and would, of course, exhibit all the characteristics of the best oleanders. All creative challenges contain inherent risk, however, and the Turners developed their first miniature in 1983 only to lose it in the aftermath of a storm. It was an ideal hanging basket plant with double pink flowers on cascading branches. We mention this to inspire anyone interested in hybridizing to begin — there is much more to be accomplished in the world of oleanders. As can be seen by the dates of introduction of new varieties from the Turners and Monrovia Nursery Company (listed in Chapter 5), some of the finest cultivars have been introduced in the past several years and more are still to come! (See also Chapter 14 on Plant Patents.)

If current research through hybridization or by the exchange of plants is successful in developing more cold hardy varieties, then oleanders can be grown in areas other than Zones 8, 9, and 10 and their popularity will increase dramatically. Three or four years ago Dr. Jerry Parsons and Greg Grant (of Lone Star Growers in San Antonio) visited members of the International Oleander Society in Galveston and were given cuttings of the five hardiest selections that had survived numerous freezes. Dr. Parsons notes that until this time they only knew of the cold hardiness of 'Hardy Red', 'Pink Beauty' (aka 'Hardy Pink') and possibly 'Little Red', varieties that survived the 1983 freeze in San Antonio when temperatures plummeted to six degrees and remained below ten degrees for many days. As Dr. Parsons commented, "It was terrible. It wiped out the entire citrus nursery business in Texas — right to the ground. It took the nursery industry to its knees." The cuttings given to Dr. Parsons and Greg Grant were rooted and have been grown in the field for several years. After several winters they plan to locate the survivors farther and farther north to continue the selection process.

Additional research has been undertaken by Dr. Jerry Parsons and Dr. Wayne McKay in El Paso. Using seeds supplied by Kewpie Gaido and Elizabeth Head that Dr. Parsons had irradiated at Texas A&M University, their goal is to determine whether there are any oleanders superior to industry standards in terms of color, dwarfing/ cold tolerance, etc. Approximately 600 seedlings were planted at the experimental

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station in El Paso and excess seedlings were taken by Dr. Parsons and planted at Lone Star Growers in San Antonio. In El Paso normal winter temperatures are at the edge of the cold tolerance range for most oleanders (Zone 7B), but Dr. McKay pointed out that until this year (1995-96) there has only been one severe winter when the temperature dropped to 10 degrees for one night and into the low teens for several nights. All plants were examined to determine freeze damage. No plants were killed to the ground but any plants with burn-back of the tops were destroyed. This eliminated approximately half of the total number. The remaining plants did not show any signs of winter injury. The seedlings are approximately four years old and most flowered in the first year. Plants range in size from dwarf to large and have exhibited almost every shade from white to red, including salmon and pink, and several that appear new and of exceptional color. In the near future Dr. Parsons and Dr. McKay will propagate any promising plant to test it on its own, and secondarily, collect seed from that plant to determine the results of the irradiation on its progeny. This note on irradiating seeds is offered by Dr. Parsons:

We found out that when you irradiate a seed, you can possibly get mutations or "sports" from the initial planting of seedlings, but the best chances [for mutations] are when you collect seed from those [irradiated] plants. Out of all those hundreds of seedlings, he [Dr. McKay at El Paso] took the ones he could plant in his block — when you're dealing with an experiment station, a research station, they have to have a certain number of plants when they plant their plots; in other words, there have to be exact numbers of every kind of treatment. I took the rest of them, which were just throwaways — I have this thing about throwing away plants — and put them out here at Lone Star [Growers], and it's amazing the differences we have. You can go out there and walk up and down the line and every single one of them is different.

We have reports that some exceptionally cold hardy plants have been developed in Israel and Italy. It would be an exciting project for a group or individual to perform a series of controlled crosses between these varieties and some of the most promising cold tolerant American varieties.

When at last I took the time to look into the heart of a flower,

                it opened up a whole new world....

as if a window had been opened to let in the sun.

                                     Princess Grace of Monaco

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