Patent Grant
PP34687
Latin name: Myrica cerifera.
Varietal denomination: ‘Whit XXIX’.
The present invention relates to a new and distinct variety or cultivar of the native evergreen shrub, Myrica cerifera, commonly known as Southern Wax Myrtle.
Southern wax myrtle is a small, aromatic, evergreen shrub or small tree. Native populations exist from east Texas across the south and northward to New Jersey. Seedlings typically grow 8 to 12 feet tall with an occasional plant reaching 20 feet. Wax myrtle grow well in sun or shade and in a wide range of soils, from marginally drained stream banks to deep sands and clay, plus are very drought tolerant. Contributing to this wide adaptability is the root association with the nitrogen fixing bacterium, Frankia alni. The bacterium is able to take nitrogen from air and convert it to nitrate, which allows this and others in the genus to grow on very marginal soils. In native coastal regions, wax myrtle can be weedy due to the large quantity of seeds produced. The seed dispersal is mostly by numerous bird species especially quail and turkey.
Wax myrtle is effective as a hedge or screen in reducing noise from adjacent areas. For example, in 1973, Whitcomb and Stowers studied the effectiveness of a number of species as hedges using a sound generator, lawn mower and automobile. They found that a broadleaved evergreen hedge was most efficient giving a 5 to 7 decibel reduction in sound 10 or 20 feet behind the hedge. In the study, width of the hedge was less important than leaf characteristics, particularly with low frequency sounds. A reduction of 5 decibels amounts to a reduction of about 50% in the apparent loudness of a sound. The new wax myrtle, ‘Whit XXIX’ has particularly dense foliage which would enhance effectiveness as a noise reducer.
The breeding/selection program with southern wax myrtle began in 1988. Initial seeds for the study were collected in the Appalachian Mountains in northwestern Virginia at or near the northern limit of the native population. That same year, seeds were also collected from a native population near Birmingham, Ala. Seedlings from those collections were planted in fields near Stillwater, Okla. The objective was an evaluation of tolerance to cold, drought, drying winds and heavy clay soils in the northern part of hardiness zone 7. When seedlings were four years old, a cold level of −2 F killed all seedlings from Alabama but did not harm seedlings from Virginia. During the succeeding years and 8 generations [consistently selecting the best seedlings for parents for the next generation, seeds were saved from the most cold-tolerant seedlings with darkest foliage and planted in open fields for evaluation. In 2015, seedlings from a selected parent showing promise and were planted in the field. From this seedling population there were 32 seedlings. During a period in February 2021, temperatures dropped to −1, then −18, then −6 F. By March, many seedlings were dead, while others had lost most of their leaves but recovered with spring growth. One seedling showed no damage or leaf discoloration in March and had the same appearance as the previous November. This seedling was selected for further evaluation and has been given the cultivar name ‘Whit XXIX’.
U.S. Plant Pat. No. 7,555, by Brackin claims a wax myrtle with deeply serrated leaves with a yellow-green mid-rib and resistance to leaf spot disease and cold hardy to −4 F.
U.S. Plant Pat. No. 6,411, by Craven claims a wax myrtle with compact growth with a broad spreading, suckering mounded growth habit, light yellow-green leaves that mature to dark olive green and cold hardy to 0 F.
U.S. Plant Pat. No. 18,731 by McCracken claims a wax myrtle plant with densely branched brilliant yellow foliage, with no mention of cold tolerance.
U.S. Plant Pat. No. 19,789 by Barrett claims a wax myrtle with compact upright, globular growth habit, and grows well between +32 F and +85 F, but no mention of tolerance to cold.
Southern wax myrtle are reportedly resistant to damage by grazing or rubbing by white tail deer, likely due to volatile oils from leaves and stems. With a high population of white tail deer in central Oklahoma, no deer damage has occurred to any of the seedlings grown during the 30+ years of this study.
The plant of the present invention is a new and distinct variety of southern wax myrtle, Myrica cerifera, which has been given the cultivar name ‘Whit XXIX’. It is characterized by an upright growth habit with dense evergreen foliage which is aromatic and resistant to damage by white tail deer and tolerant to cold down to −18 F. Foliage is dense, with the many broad flat leaves making it effective as a visual barrier as well as noise reduction.
Visual observation suggested more dense branching and more leaves on ‘Whit XXIX’ compared to other plants of similar size and age. To differentiate and document differences in foliage and branching characteristics between the new variety, ‘Whit XXIX’ and other seedlings growing in adjacent rows from the same parent population or previous populations from other parents, comparisons of six-inch lengths of stems were evaluated for number of leaves on eight stems on a plant with the first flush (spring growth) and second (summer flush). The number of leaves on first flush from eight branches on ‘Whit XXIX’ averaged 34.1. The number of leaves from eight branches on six other plants of similar size and age averaged 28.1, 20.2, 19.5, 20.9, 15.5 and 16.4. There were few branches on any of the first flush branches on any of the plants evaluated. With the seed populations grown and evaluated during the 30+ years of this research, branches are primarily produced on the second/summer flush.
The number of developing branches per six-inch section of second/summer flush of ‘Whit XXIX’ on 8 branches counted averaged 21.1. The number of branches on various other wax myrtle plants of similar size and age and with 8 branches counted on each plant averaged 10.75, 7.6, 11.9, 12.4, 14.1 and 9.8.
The following is a botanical description of the new and distinct variety of southern wax myrtle, Myrica cerifera which has been given the cultivar name ‘Whit XXIX’. Specific color designations set forth by number designation are in accordance with The Royal Horticultural Society Colour Chart (1966). General color recitations are consistent with ordinary American color terminology.
The plant was 7 years old and was grown outdoors in an open field of sandy, clay loam near Stillwater, Okla. Drip irrigation was applied for the first two years, but in years 3 to 7, no drip was applied in order to evaluate drought tolerance. No signs of drought stress were observed.
| Number | Name | Date | Kind |
|---|---|---|---|
| PP6411 | Craven, III | Nov 1988 | P |
| PP7555 | Bracken | Jun 1991 | P |
| PP18731 | McCracken | Apr 2008 | P2 |
| PP19789 | Barrett | Mar 2009 | P2 |
