Viburnum plant named ‘NCVX3’

Latin name of the genus and species: Viburnum davidii x propinquum.

Variety denomination: ‘NCVX3’.

The new Viburnum cultivar is a product of a planned breeding program conducted by the inventor in Mills River, N.C. The cross resulting in this new variety was made during Summer of 2010. The objective of the breeding program was to develop new plant forms of Viburnum for commercial horticultural purposes.

The seed parent of ‘NCVX3’ is the unpatented, proprietary seedling referred to as ‘NCSU 2007-187’. The pollen parent is the unpatented, proprietary seedling referred to as ‘NCSU 2007-080’. The new variety was identified as a potentially interesting selection in the July of 2012, at a research greenhouse in Mills River, N.C.

The first asexual propagation of ‘NCVX3’ was carried out in July of 2012 by rooting stem cuttings at the same research greenhouse in Mills River, N.C. and has been asexually reproduced repeatedly. ‘NCVX3’ has been found to retain its distinctive characteristics through successive asexual propagations.

The cultivar ‘NCVX3’ has not been observed under all possible environmental conditions. The phenotype may vary somewhat with variations in environment such as temperature, day length, and light intensity, without, however, any variance in genotype.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘NCVX3’. These characteristics in combination distinguish ‘NCVX3’ as a new and distinct Viburnum cultivar:

1. A compact, prostrate habit. 2. Glossy, dark evergreen leaves. 3. Abundant white flowers in spring.

Plants of the new cultivar ‘NCVX3’ are similar to plants of the seed parent in most horticultural characteristics, however, plants of the new cultivar ‘NCVX3’ differ in the following;

1. The new variety has lighter green foliage. 2. The new variety has smaller flowers than the seed parent.

Plants of the new cultivar ‘NCVX3’ are similar to plants of the pollen parent in most horticultural characteristics, however, plants of the new cultivar ‘NCVX3’ differ in the following;

1. Plants of ‘NCVX3’ are more compact than plants of the pollen parent. 2. Flowers of the new variety are larger and showier than the flowers of the pollen parent.

Plants of the new cultivar ‘NCVX3’ can be compared to the commercial variety Viburnum ‘Jermyns Globe’, unpatented. These varieties are similar in most horticultural characteristics; however, ‘NCVX3’ differs in the following:

1. The new variety produces lighter green foliage, this comparator produces darker green foliage with a blue tinge. 2. Flower buds of ‘NCVX3’ are white, flower buds of this comparator are pink.

‘NCVX3’ can also be compared to ‘NCVX2’, U.S. Plant patent application Ser. No. 16/903,184. ‘NCVX3’ is smaller in size (height: 50 to 70 cm; width: 90 to 120 cm), with a more prostrate habit, smaller leaves (length 2.2 to 6 cm; width: 1 to 2.5 cm), and a larger inflorescence diameter (5 to 10 cm.). Compared to ‘NCVX3’, ‘NCVX2’ is larger in size (height: 80 to 120 cm; width: 100 to 120 cm), with a globose habit, larger leaves (length 4 to 9 cm; width: 1.5 to 3.7 cm), and a smaller inflorescence diameter (4 to 5 cm).

This new smooth-leaf Viburnum ( Viburnum davidii x propinquum ) is illustrated by the accompanying photographs which show the plant's form, foliage and inflorescences. The colors shown are as true as can be reasonably obtained by conventional photographic procedures. Colors in the photographs may differ slightly from the color values cited in the detailed botanical description, which accurately describe the colors of the new Viburnum cultivar. Age of the plant is about 2 years.

FIG. 1 is a photograph showing white inflorescences and dark green foliage of ‘NCVX3’ taken in Grand Haven, Mich. in May 2019.

FIG. 2 is a photograph showing the habit of a field-grown plant of ‘NCVX3’ taken in Jackson Springs N.C. in September 2019.

FIG. 3 is a photograph of the dark green lustrous foliage of ‘NCVX3’ taken in Jackson Springs N.C. in September 2019.

The following is a detailed description of the botanical characteristics of the new and distinct smooth Viburnum ( Viburnum davidii x propinquum ) known by the denomination ‘NCVX3’. The detailed description was taken on a 3-year-old field-grown plant in Jackson Springs, N.C. in 2019. All colors cited herein refer to The Royal Horticultural Society Colour Chart (The Royal Horticultural Society (R.H.S.), London, 2001 Edition). Where pertinent, descriptive data was supplemented with information provided from cooperators in Grand Haven, Mich. where data was taken on 3 -year-old container plants as well as plants in a landscape setting. Where specific dimensions, sizes, colors, and other characteristics are given, it is to be understood that such characteristics are approximations or averages set forth as accurately as practicable.

Botanical classification: Viburnum davidii x propinquum ‘NCVX3’.

Typical method: Softwood cuttings.

Time to initiate rooting: 28 days at approximately 27° C.

Time to produce a rooted young plant: About 3 months at approximately 27° C.

Root description: Dense, free branching roots of moderate thickness. Colored yellow-white, not accurately measured with an R.H.S. chart.

Plant type: Perennial evergreen flowering shrub.

Plant description:

Growth habit .—Densely branched, prostrate. Height.— 50 to 70 cm. Width.— 90 to 120 cm.

Shoot and stem:

Lateral branch length .—Avg. 24 cm (18 to 30 cm). Lateral branch diameter .—Avg. 0.4 cm (0.2 to 0.5 cm). Internode length .—Avg. 4.5 cm (1 to 7 cm). Immature shoot texture ( current year ).—Glabrous. Immature shoot color ( current year ).—Greyed-Purple (187A). Mature stem texture ( from prior year ).—Glabrous, with lenticels and fissures. Mature stem color ( from prior year ).—Brown (200C).

Plant vigor: Moderate.

Leaf:

Type: Simple.

Persistence .—Evergreen. Arrangement .—Opposite. Shape .—Elliptical. Apex .—Acute. Base .—Rounded. Venation .—Pinnate. Vein color .—Upper: Red-Purple (59A). Lower: Greyed-Purple (184C). Margins .—Entire or obscurely denticulate. Emerging leaves .—Color: Upper: Greyed-Purple (183A). Lower: Green (138B). Texture: Glabrous. Mature leaves during growing season .—Color: Upper: Green (NN137A). Lower: Yellow-Green (147B). Texture: Coriaceous and glabrous. Length of lamina: Avg. 4 cm (2.2 to 6 cm). Width: Avg. 2 cm (1 to 2.5 cm). Leaf attachment .—Petiolate. Petiole .—Length: Avg. 0.8 cm (0.6 to 1 cm). Diameter: 0.1 cm Color: Purple (N77A). Texture: Glabrous.

Flower:

Description .—Single flowers arranged on terminal cymes. Flower longevity .—About 1 week. Number of flowers per inflorescence.— 50 to 250. Flowering season .—Mid-April to early May in Mills River, N.C. Fragrance .—Slight fragrance. Inflorescence .—Diameter: Average 8 cm (5 to 10 cm). Height: Average 4 cm (2 to 6.5 cm). Flower .—Diameter: 0.5 cm. Height: 0.4 cm. Bud .—Shape: Round. Length: About 0.2 cm. Diameter: About 0.2 cm. Color: White (155B). Petals .—Number: 5 fused, reflexed petals. Arrangement: Whorled. Length: 0.2 cm. Width: 0.1 cm. Shape: Oblong. Margin: Entire. Apex: Rounded. Texture: Glabrous. Color: White (155D). Sepal .—Number: 5. Arrangement: Whorled. Length: Less than 0.1 cm. Width: Less than 0.1 cm. Shape: Fused. Margin: Entire. Apex: Acute. Base: Fused. Texture: Glabrous. Color: Green (143C). Peduncle .—Length: Average 4.5 cm (3 to 6 cm). Diameter: About 0.2 cm. Texture: Glabrous. Color: Yellow-Green (144C). Pedicels .—Length: Average 0.4 cm (0.1 to 0.6). Diameter: Less than 0.1 cm. Texture: Glabrous. Color: Yellow-Green (144B).

Gynoecium:

Pistil number.— 1. Pistil length .—Less than 0.1 cm. Stigma shape .—Rounded. Stigma color .—Yellow-Green (144D). Style length .—Less than 0.1 cm. Style color .—Yellow-Green (144D).

Androecium:

Stamen number.— 5. Anther shape .—Oblong. Anther size .—Less than 0.1 cm. Anther color .—Brown (200A). Amount of pollen .—Moderate. Pollen color .—White (155B).

Fruit and seed: None observed.

Disease and insect resistance: No significant resistance nor susceptibility to disease or insect pests has been observed.

Cold hardiness: At least USDA zone 7a; testing has not been completed in colder zones.