Styrax japonicus (Japanese snowbell) is a small deciduous tree that is native to Japan, China, Korea, Taiwan and the Philippines (2). The species grows from 6 to 9 m (20 to 30 ft) in height with a similar spread, making it a valuable plant for use in small residential landscapes or under utility lines. Flowers are bell-shaped, approximately 2 cm (3/4 in) in diameter, and very fragrant. They are produced in mid-spring and hang beneath the foliage in three- to six-flowered racemes. Foliage is medium to dark green in summer and may turn yellow in fall. The species is generally pest free, even though problems with ambrosia beetles, Xylosandrus spp., have been reported (3, 6).
Despite its outstanding ornamental attributes, S. japonicus is not widely utilized in the United States. Problems with branch dieback and lack of flowering have been reported for several cultivars (2, 3, 4). Late spring freezes often damage newly emerged foliage and may even lead to plant death (2; personal observation). Considerable variability among open-pollinated S. japonicus seedlings for time of vegetative bud break and susceptibility to late spring freeze damage has been reported (4). ‘Spring Showers’ is the result of efforts to identify plants with delayed bud break and outstanding ornamental traits that could expand the use of this species in areas of the country that are often subject to late spring freezes.
A group of open-pollinated seedlings was obtained from Heritage Seedlings (Salem, OR) and planted in the field at the Tennessee State University Nursery Research Center in McMinnville, TN, in 1998. Plants were evaluated for time of bud break in 1999 and 2000 (4); a selection, referred to in that publication as G258-22, was selected for further evaluation in 2000. In 2003 and 2004, plants of this selection were sent for evaluation to nursery and university cooperators in Alabama, Florida, Georgia, Indiana, Kentucky, Louisiana, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, and Virginia. After evaluation in these locations, this selection was released in 2011 under the name ‘Spring Showers’.
The cultivar name Spring Showers was registered in 2011 with the International Cultivar Registration Authority for unassigned woody ornamental genera in accordance with the International Code of Nomenclature for Cultivated Plants (1). Herbarium specimens of ‘Spring Showers’ have been deposited at the U.S. National Arboretum Herbarium as cultivar standards.
Styrax japonicus ‘Spring Showers’ (NA 71587; PI 660970) is a deciduous, small tree (Fig. 1) that reached 3.6 m (12 ft) high and 2.4 m (8 ft) wide in 10 years of growth in McMinnville, TN (USDA Cold Hardiness Zone 6b; Waynesboro silt loam), under full sun conditions. Mature leaves are simple, broad-elliptic to elliptic-oblong, and up to 10 cm (4 in) long and 5 cm (2 in) wide. Foliage is dark green [RHS 147A (5)] on the adaxial leaf surface. Flowering occurs in mid to late spring. Flowers are white (RHS NN155D), 2 cm in diameter, and are held below the foliage. Flowers are followed by drupes that drop by mid to late fall.
Adaptability and Cultural Conditions
Statements and recommendations on plant performance and culture are based on information provided by nursery and university cooperators in multiple locations looking at three plants per site as well as plant performance in replicated trials at the Nursery Research Center in McMinnville, TN. Like other japanese snowbells, ‘Spring Showers’ grows well in a moist, acidic, well-drained soil. It is hardy in USDA Cold Hardiness Zones 5 to 8 and can be grown in full or partial sun.
‘Spring Showers’ can be propagated from softwood cuttings using intermittent mist and 3000 ppm indole-3-butyric acid with rooting occurring within 4 weeks. Plants are suitable for either field or container production.
‘Spring Showers’ is well suited for use as a specimen plant, in mixed borders, or in height restricted planting areas such as under utility lines. Because of its delayed bud break, ‘Spring Showers’ is particularly useful in areas that are frequently subject to late spring freezes. ‘Spring Showers’ is an attractive selection with dark green, lustrous foliage, upright growth habit and heavy flower production.
Like other woody ornamental plants released from the National Arboretum, ‘Spring Showers’ is not patented, so may be propagated and sold freely. Plants are available from wholesale, mail-order, and a limited number of retail nurseries (source list available on request). The National Arboretum does not have plants of these cultivars available for general distribution but can supply cuttings to nurseries wanting to propagate these plants.
Mention of trade names of commercial products in the publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.
2Research Geneticist. Sandra.Reed@ars.usda.gov.