Seven Out of 1,200: The Long Road to a Better Hibiscus Episode Description John Ruter put 1,200 hibiscus seedlings in the ground and kept seven. The other 1,193 got bush hogged. He is the Armitage Professor of Horticulture at the University of Georgia and the director of the UGA Trial Gardens, and this week he walks Ping through everything that happens between a cross and a plant you can actually buy. It takes ten to fifteen years, and in his case it started with a phone call from a mountain research station. The superintendent at Blairsville told him to come up and look at his hibiscus. When John got there the plants were covered in hibiscus sawfly, which runs four generations a year in Georgia. His answer came from a native species with hairy leaves. Under the microscope, Hibiscus grandiflorus looked like old shag carpet, and it had zero feeding damage. Moving that hairiness into his red-leaved selections cost him an F2 and a backcross and several years, and it produced the first hardy hibiscus ever released with sawfly resistance. Five of those plants became the Head Over Heels series. There is a lot here beyond hibiscus. John explains why an Asian species and an American species usually will not make a fertile hybrid, using a dance-floor image that lands in one sentence. He explains why hardy hibiscus cannot be propagated offshore like almost everything else in the trade, why every cultivar he releases starts with the letters RUT, and what he does with graduate students that put three of them in first, second and third place at the same symposium. Ping brings her own hibiscus story too, from Chengdu, where Hibiscus mutabilis is the city flower. Listen Time: 52:28 Follow Along with the Transcript In This Episode Guest Dr. John Ruter, Armitage Professor of Horticulture, University of Georgia, and Director of the UGA Trial Gardens. He teaches three courses and runs an ornamental plant breeding program covering both herbaceous and woody plants. Past and current work includes hibiscus, Ilex, camellias, conifers, Salvia, Pycnanthemum and Lagerstroemia. His first release, the holly Emerald Colonnade, is now used as a boxwood replacement on estates. Host: Dr. Ping Yu, UGA Department of Horticulture Main Topics Welcome (00:00) Meet John Ruter, and the spark at twelve (00:42). A seventh-grade shop rotation in the San Fernando Valley, a Christmas tree farm, FFA competitions attended alone, and Cal Poly San Luis Obispo Seven acres, no water: becoming a breeder (07:06). Arriving at UGA Tifton, digging a well, building collections in what he calls the forgotten zone of horticulture How the hibiscus program started (12:24). Fleming Brothers germplasm, late emergence, lodging, the flag exercise, 1,200 seedlings, and the sawfly call from Blairsville Mutabilis, Taiwan, and the chromosome problem (18:47). Flowers on a stick, three-species crosses, and why diploid by tetraploid usually ends in a sterile plant From cross to catalog: ten to fifteen years (27:09). The 2009 to 2017 timeline, branded programs, and the cotton quarantine that keeps hardy hibiscus propagation at home Naming a cultivar: the RUT system (36:04). Nonsensical cultivar names, trademark names, and who actually gets to pick What is next for the program (39:54). All six species crossed both directions, an F2 population, HPLC pigment work, and an annotated Hibiscus moscheutos genome Advice for the next generation (45:33). Turning students loose, letting them hire their own labor, and the road trips Closing (51:44) Key Highlights The flag exercise (14:11). Garden club visitors got flags and were told to mark their favorites in the research plots. It did not matter how ugly the plant was. If it had red foliage, it got flagged, and that told John where to aim. Seven out of 1,200 (15:00). The first big population went in the ground around 2012 and was rated for aerial Phytophthora, Cercospora, Alternaria, flower size, color and foliage. Seven were kept. Shag carpet under the microscope (16:30). Hibiscus grandiflorus carries so many trichomes that the sawfly larvae leave it alone completely. That plant became the resistance source. The Head Over Heels series (18:08). Five selections, and the first hardy hibiscus on the market with sawfly resistance. Growers along the eastern shore had been giving up on the crop, even on native plants. Flowers on a stick (19:40). Hibiscus mutabilis drops all its foliage when it goes reproductive, leaving blooms on the end of a bare six to eight foot stem. Crossing in Hibiscus taiwanensis fixed the foliage and blew the height up to twelve feet, so a third species from the islands south of Japan, Hibiscus makinoi, brought it back down to four to six feet. Nobody has a dance partner (27:00). The clearest explanation of triploid sterility you will hear this year, in one sentence. Related to cotton, so it stays home (30:56). Most ornamental cutting production happens in Costa Rica, Central America, South America or Africa. Hardy hibiscus cannot go, because of cotton disease quarantine, so the companies had to find a domestic propagator. RutHib1 through RutHib5 (38:00). First three letters of the breeder’s last name, first three letters of the genus, then a number. The hollies are up to RutIle10. Yaupon holly makes caffeine (43:54). Ilex vomitoria is the only North American native that produces it, and in a substantial amount. John has a collaboration looking at it as a native tea plant. The patent clock (50:46). Post a photo of an unreleased plant, or let it land in somebody’s catalog, and you have one year to file. Key Quotes “And we ended up picking seven out of 1,200 to keep.” Dr. John Ruter (15:00) “it looked like old shag carpet growing on the leaves, and we noticed that they had zero damage” Dr. John Ruter, on the trichomes of Hibiscus grandiflorus (16:30) “The hybrid ends up with three sets of chromosomes and somebody doesn’t have a dance partner.” Dr. John Ruter, on triploid sterility (27:00) “So it’s always a number game.” Dr. Ping Yu (18:42) “I don’t baby them, I don’t hold their hand, I don’t call them every day and say this is what you’re doing today.” Dr. John Ruter, on advising graduate students (46:31) Educational Highlights Hibiscus sawfly. A Hymenoptera insect, so it sits in the bee family. The larvae are what chew the foliage. The adults look like a little black fly with a red orange thorax. Georgia gets four generations a year, which is why it turns into a real production problem rather than a nuisance. Trichomes. Plant hairs. Hibiscus grandiflorus is loaded with them, and that physical barrier is what gives it complete sawfly resistance. Breeding the trait in has a visible cost: the trichomes shift the red foliage toward a matte red-gray rather than a glossy red. Lodging. John gives the definition himself. It is an agronomic term for falling over, and it was one of the original flaws he set out to fix in the hardy hibiscus of the late 2000s, alongside late spring emergence. Heterosis. Also called hybrid vigor. His mutabilis by taiwanensis F1 hybrids hit ten to twelve feet in a single season, which is the effect working exactly as advertised and also more plant than any nurseryman wanted. Ploidy, and why crosses fail. The hardy hibiscus native to the eastern United States are diploids, two sets of chromosomes. The Asian species, including Hibiscus mutabilis, taiwanensis and Hibiscus syriacus, the Rose of Sharon, are generally tetraploids with four sets, and their base chromosome number is different too. Cross a diploid with a tetraploid and the offspring gets three sets. One set has nothing to pair with at meiosis, and the plant is sterile. John compares such a hybrid to a mule. Cultivar name versus marketing name. The cultivar name is the permanent botanical identifier and it is often deliberately nonsensical, which is why UGA settled on the RUT prefix for everything out of John’s program. The trademark or marketing name is what appears on the pot, and in the last ten to fifteen years the companies have wanted to choose that themselves, along with the series name. The one-year patent clock. In the United States, a public disclosure that reads as an offer for sale starts a twelve-month window to file a plant patent. That is why an unreleased selection photographed on a garden tour, or printed in a catalog by accident, becomes an urgent filing rather than a minor problem. Mountain mint. John’s program holds 16 or 17 of the 19 native Pycnanthemum species and has just finished a four-year garden trial. Only two named cultivars exist. It is a strong pollinator plant, and the species are distinct enough that you can often tell them apart by the scent of the foliage. Resources & Links Website: bandbpod.com UGA Trial Gardens, Athens, Georgia. Dr. Ruter is the director, and his invitation in this episode is to come visit in person University of Georgia faculty profile for Dr. John Ruter The Head Over Heels hardy hibiscus series, the five-plant release discussed at 18:08 Organizations that come up in the conversation: the Holly Society of America, the U.S. National Arboretum, the University of Georgia Research Foundation (UGARF), the International Plant Propagators’ Society (IPPS), the International Society for Horticultural Science (ISHS), and the American Society for Horticultural Science (ASHS) Related listening: S02E08 with Dr. Ryan Contreras, who did his PhD with Dr. Ruter About Blooms and Beyond Blooms and Beyond explores plant history, culture, and management through the lens of science. Whether you’re a commercial grower seeking practical solutions, a student exploring careers in horticulture, or simply someone who loves plants and their stories, there’s something here for you. Hosted by Dr. Ping Yu of the University of Georgia, each episode features interviews with experts who share enchanting stories, cutting-edge research, and practi
