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Dr. John M. Ruter
University of Georgia
Department of Horticulture
Coastal Plain Experiment Station
Tifton, GA 31793-0748
A paper from the Proceedings of the 12th Metropolitan Tree Improvement Alliance Conference (METRIA 12), Landscape Plant Symposium: Plant Development And Utilization, held in Asheville, NC, May 23-25, 2002, co-sponsored by the North Carolina State University, North Carolina Division of Forest Resources, USDA Forest Service Southern Region, North Carolina Landscape Association, North Carolina Association of Nurserymen, The Landscape Plant Development Center, The North American Branch of The Maple Society, and The International Ornamental Crabapple Society.
The Tifton Campus of the University of Georgia is situated in south central Georgia, approximately 65 miles north of the Florida state line. According to the USDA hardiness zone map, Tifton is located in USDA 8a. The mean temperature of our coldest month is 10.0C, and the lowest temperature we have experienced in my twelve years is -10.6C. The mean temperature of our warmest month is 27.2C and we regularly have 90 to 100 days per year with temperatures at or above 32.2C.
Prior to taking my current position there had never been an ornamental horticulture researcher in south Georgia. Many plant recommendations were based on observations from USDA 7, not USDA 8. As differences in soil types, chilling hours, and numerous other environmental variables exist within the state, it became imperative that plant material needed to be developed and evaluated under south Georgia conditions.
Plant development and selection was initiated in 1991 for 1) development of a native plant arboretum, and 2) to add regional germplasm for a red maple evaluation project with the U.S. National Arboretum. Beginning in 1995 other seed sources for numerous species were sought to begin evaluating plants for USDA 8 conditions. Development of plant material so far has been by 1) propagation of seed, 2) finding plants in natural habitats or cultivated situations (vegetative propagation), or 3) having plants brought to my attention for consideration. Examples of all three are given below.
Two plants with commercial appeal that appeared as variegated seedlings are Cyrilla racemiflora 'Spring Cloud' and Liquidambar formosana (yellow variegated form). The variegated Cyrilla appeared in a batch of seedlings from a plant growing in Tift County, GA. The foliage emerges golden yellow and then becomes mottled with white variegation before turning green during the heat of the summer. The variegated Formosan sweet gum came up as a seedling in a batch of plants that we were growing for a pot-in-pot production study. The leaves are a uniform golden yellow after emerging with a purplish tint in the spring. Both plants have been successfully propagated from cuttings.
A selection of Campsis sp. was found growing on a fence row at an abandoned home site in Tift County, GA. The flowers are larger and showier than our native trumpet creeper. The foliage is light green and more pubescent than published descriptions of species and hybrids. The flower is intermediate between C. radicans and C. chinensis. Illicium floridanum 'Pebblebrook' was found growing in a backyard in Tifton. The plant was one of three planted in dappled shade. The two other plants had typical open-floppy growth characteristic of the species, but 'Pebblebrook' stood out as a compact form with no pruning. Commercial growers like the plant because it does not require excessive pruning during production. Ilex decidua (CPES#3) was brought to my attention for its show of berries in the winter. The commercial varieties currently available are all northern selections and their fruit sunburns during our winters. This selection holds its color until the cedar waxwings migrate through and strip the fruit in March.
These are just of few of the selections being evaluated and prepared for release from my program. Other groups of plants being evaluated in South Georgia include Acer, Cotoneaster, Evergreen Ferns, Gardenia, Hydrangea, Ilex, Illicium, Ornamental Conifers, Ornamental Grasses, Prunus, Rhaphiolepis, Spiraea, Syringa, and Viburnum. I also oversee the Coastal Plain Research Arboretum in Tifton which has ~ 250 different taxa of species native to the Coastal Plain region of Georgia. The following is a partial list of plants that have done well in Tifton and are being evaluated for the nursery and landscape trade. It is hoped that some of these plants will be released from the University of Georgia in the near future.
Acer oliverianum ssp. formosanum
Amelanchier arborea (pink-flowering form)
Callistemon sp. (red flowers)
Callistemon sp. (mauve flowers)
Chamaecyparis obtusa var. formosana
Chionanthus retusus (Valdosta selection)
Cornus florida 'Gold Braid' PP13085 (heat tolerant, variegated form)
Cotoneaster lacteus (compact form)
Cyrilla racemiflora 'Spring Cloud'
Elliottia racemosa (Turner Co. selection)
Ilex x attenuata (seedlings)
Ilex cassine (Ocala selection)
Ilex cornuta 'Batwing'
Ilex cornuta 'RPV Special'
Ilex cornuta (Rotunda BS)
Ilex decidua (CPES #3)
Ilex x 'James Swan'
Ilex x wandoensis (compact form)
Illicium floridanum 'Pebblebrook'
Liquidambar formosana (variegated form)
Oxydendrum arboreum (south GA seed source)
Pennisetum purpureum (perennial in USDA 8a)
Pistacia chinensis (male selection with good form and fall color)
Pittosporum tobira (cold hardy and compact forms)
Pittosporum heterophyllum (compact form)
Quercus x comptoniae (fastigiate and semi-evergreen form)
Rhaphiolepis x delcourii 'Georgia Petite'
Thuja orientalis var. Xianshanensis
Viburnum nudum var. nudum (compact, south Georgia selection)
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