Azalea plant named ‘Roblen’

Abstract

A new and distinct variety of Azalea plant named ‘Roblen’, characterized by its unique blooming time, upright, dense and globose growth habit, and attractive single to semi-double red flowers.

Description

Genus species: Rhodendron hybrid.

Varietal denomination: ‘Roblen’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct variety of evergreen Azalea of the genus Rhododendron and a member of the Ericaceae family. This new Azalea variety, hereinafter referred to as ‘Roblen’, was discovered by Robert Edward Lee in August, 1998 in Independence, La. ‘Roblen’ originated from a controlled breeding program in Independence, La. The objective of the breeding program was to create new Azalea varieties which have unique blooming periods, bloom colors, bloom forms, bloom sizes, and growth habits. ‘Roblen’ originated from a cross made by Mr. Lee in April, 1996 of the cultivar ‘Watchet’ (unpatented) as the female, or seed, parent with the proprietary hybrid seedling number 2-32 (unpatented) as the male, or pollen, parent.

Asexual propagation of the new plant cuttings has been under Mr. Lee's direction at the same location. The new plant retains its distinctive characteristics and reproduces true to type in successive generations. The plant cannot be reproduced true from seed.

SUMMARY OF THE INVENTION

The following are the most outstanding and distinguishing characteristics of this new cultivar when grown under normal horticultural practices in Independence, La.

• • 1. The unique spring, summer, and fall blooming.
  • 2. A red flower color Red Group 44C with dotting color Red Group 53C.
  • 3. Single to semi-double flowers ranging in size from 1¾″ to 2¼″ in diameter.
  • 4. Easily propagated with semi-hardwood cuttings in late spring through the summer.
  • 5. Fast growth rate under normal fertilization and moisture conditions.
  • 6. Upright, dense and globose in nature.
  • 7. Good specimen plant.
  • 8. Desirable in planters.
  • 9. Makes a very good hedge or screen.
  • 10. Very good foundation plant.
  • 11. Does well as an understory plant in a woodland garden.
  • 12. Hardy to Zone 7.
  • 13. Attracts butterflies.

DESCRIPTION OF THE DRAWINGS

This new Azalea hybrid variety is illustrated by the accompanying photographic prints in which:

1. The photograph at the top of the sheet is a close-up showing flower, foliage, and stem color as well as flower size and form.

2. The photograph at the bottom of the sheet shows the upright, dense and globose growth habit of a young three gallon plant.

The colors shown are as true as is reasonably possible to obtain by conventional photographic procedures. Colors in the photographs may appear different than actual colors due to light reflectance. The colors of the various plant parts are defined with reference to The Royal Horticultural Society Colour Chart. Description of colors in ordinary terms are presented where appropriate for clarity in meaning.

BOTANICAL DESCRIPTION OF THE PLANT

The following is a detailed description of the new variety of Azalea based on my observations made of 2 year old plants grown in 3 gallon containers in wholesale commercial production practices, in greenhouses, and in established landscape plantings in Independence, La.

Distinctive Characteristics

TABLE 1
				R. oldhamii
				‘Fourth of
Characteristic	‘Roblen’	‘Watchet’	‘Carla’	July’
Height (Mature)	4-5′	2-3′	2-3′	8-10′
Width (Mature)	3-4′	3-4′	3-4′	6-7′
Flower Diameter	1¾-2¼″	3½-3¾″	2½-4″	1¾-2¼″
Flower Form	Single/semi-	Single	Semi-	Single
	double		double
Flower Color	Red G. 44C	Red G.	Red G.	Red G. 39A
		49B	40C
Flowers per	2-3	1-2	2-3	2-4
Terminal
Bloom Period	April	May	April	Late June >
″	Late July >			Frost
	Frost
Petal/Petaloid	5-10	5	5-10	5
Number
Hardy Zone	7	6	7	7
Stamen Number	5	10	0	7-10
Stamen Type	Some Petaloid	Non-	Petaloid	Non-Petaloid
		Petaloid

The female, or seed parent, of ‘Roblen’ is the Azalea ‘Watchet’; a moderate pink, single, late blooming, low compact grower. ‘Watchet’ is an unpatented Robin Hill hybrid developed by Robert Gartrell in Wycoff, N.J. Mr. Gartrell started his hybridization in 1937 to produce hardy, late blooming Azaleas. ‘Watchet’ is the result of a cross between the Satsuki Hybrid ‘Amagasa’ (unpatented) and the Robin Hill Hybrid ‘Lady Louise’ (unpatented).

The male, or pollen, parent of ‘Roblen’ is the product of the pollination of the cultivar ‘Carla’ (unpatented) by the cultivar ‘Fourth of July’ (unpatented). This proprietary hybrid seedling, number 2-32 was crossed with ‘Watchet’ to produce the new cultivar ‘Rublen’. ‘Roblen’ differs from number 2-32 primarily in flower color. The parentage of the new variety can be summarized as follows:
‘Watchet’×#2-32 (‘Carla’בFourth of July’)

‘Carla’ is a strong reddish orange, semi-double, mid-season blooming, low compact grower developed by North Carolina State University and Louisiana State University.

Robert Edward Lee's hybridization program was conducted with emphasis On species that are not commonly found in the genetic make-up of the present day hybrids. The ‘Fourth of July’ cultivar which Mr. Lee obtained from Dr. Thornton in 1981 is a heavy summer and fall blooming plant, not like the Rhododendron Species Foundation form. The flower buds form on new growth and start blooming about July 1. Mr. Lee used this cultivar to cross with existing hybrids which have a tendency to bloom in the fall and which are also fairly hardy. As expected the resulting seedlings are heavy summer and fall bloomers with very impressive spring blooms also.

• Classification:
• Botanic: Rhododendron hybrid ‘Roblen’.
• Form: Upright, dense, and rounded.
• Height: 4-5′.
• Width: 3-4′.
• Growth habit: Upright, dense and globose. Fast growth rate under normal fertilization and moisture conditions.
• Growth rate: In a period of six years from a rooted cutting the plant reaches a height of 3 feet and a spread of 2 feet. The growth rate is normally about 6 to 8″ per year; the plant reaches a height of 4 to 5′ at maturity while maintaining a dense habit due to the abundant branch development.
• Foliage: Alternate, simple, evergreen, pubescent, elliptic, and varying in size from 1¾″ to 2¼″ long and ¾″ to 1⅛″ wide. The margins are entire, with a petiole 3/16″ to ¼″ long. Midveins and laterals are impressed on the upper leaf surface and prominent on the underside. The base of the leaf is cuneate to attenuate and the apex is acute to mucronate. The upper surface of the immature leaves is dull, pubescent, and is Yellow-Green Group 144A and the underside is Yellow-Green Group 146D, pubescent, and matte. The upper surface of the mature leaves is Yellow-Green Group 147A, glossy and slightly pubescent and the underside is Yellow-Green Group 146B, matte, and pubescent. The immature petioles, midribs, and veins are Yellow-Green Group 146C. New growth is pubescent. These hairs are initially soft and white and cover both sides of the leaf with a higher concentration on the petioles and veins. They are slightly curled, flat, and range in length from 1/64″ to 1/32″. As the growth matures much of the leaf pubescence is lost; however, the stems, petioles, and leaf veins retain this pubescence which becomes more setaceous and darker in color (Brown Group 200B) through the growing season. The reduction of pubescence makes the leaf appear darker than Yellow-Green Group 147A.

In 2001, the date of initial spring growth was March 8, in Independence, La. After the initial spring flush there was almost continuous growth until that fall ending November 5, also in Independence, La. When grown in full sun, the internode length of this plant is ¼″ to ⅝″; when grown in light shade the internode length is ⅜″ to ¾″. As would be expected a plant grown in shade results in a taller, less dense plant with larger leaves.

The average length of terminal growth of the initial spring flush is about 5″ for a plant in full sun and about 7″ when grown in shade. This growth should not be trimmed since it will produce flowers starting in late July. As the plant continues to grow through the summer and fall more flower buds are produced, which mature and bloom until frost. This remaining growth produces about 4″ to 5″ of height. As cool weather approaches, some of the flower buds become dormant. These buds bloom in April of the next year.

• Stems: The young stems are Yellow-Green Group 146C and densely clothed with spreading white glandular hairs. During the second growing season they become Greyed-Green Group 197B, glabrous and rugose. The pith is solid and uniform. Young and older stems are densely branched.
• Buds: Tight buds at ½″ are ovate and acuminate Yellow-Green Group 146D with a hairy pubescence Brown Group 200B. The buds are borne in clusters of 2 to 3, and are sheathed by a pair of modified leaf bracts which are from ¼″ to ½″ long, persistent, and Yellow-Green Group 147A. The pedicel is ⅜″ to ⅝″ long, pubescent, and Yellow Green Group 145C. The calyx is ⅛″ to 3/16″ long, Yellow-Green Group 144B, funnel shaped, persistent, and pubescent. The five imbricated sepals are lanceolate and joined at the base to form a cup. As the buds swell the bud sheath matures to a Greyed-Orange Group 165A, falls off, and reveals the flower color Red Group 44C.
• Flowers: Perfect, single to semi-double, Red Group 44C (upper surface and under surface), glabrous, open funnel shaped, 1¾″ to 2¼″ in diameter by 2″ to 2¼″ in depth, borne on current season's growth, non-fragrant; they last on the plant in the garden 5 to 6 days. These are five true petals which are fused at the base, elliptic, and have wavy margins. These petals are 1½″ to 2″ long, ¾″ to 1¼″ wide, and have rounded apexes and entire margins. Three out of five petals are dotted with Red Group 53C. There are 5 non-petaloid stamens which are 1″ to 1¼″ long. The filaments are Red Group 39B, the anthers are Greyed-Orange Group 167B, and the pollen matures to Yellow Group 11B. The 0-5 petaloid stamens are from ¼″ to ¾″ long, ⅛″ to ⅜″ wide, and odd shaped. The margins are entire and the apexes rounded. The pistil is single, non-petaloid, 1½″ to 2″ long and Red Group 46A. The ovary is densely glandular-setose and has five locules. The capsule matures in about 5 months, in Independence, La., to about ¼″ to ½″ long; it has a persistent style, is Yellow-Green Group 146B, and contains from 100 to 400 nonwinged seeds. Normally fruit set is not heavy. There is a 2 to 3 week flowering period in April in Independence, La. Flowering resumes in July as the new buds mature and continues until frost which can be as late as November or December in Independence, La. Azaleas blooming at this time of year attract butterflies in profusion.
• Culture: Grows well in a wide range of conditions, tolerates sun to shade. Prefers a moist, well-drained soil that is rich in organic matter. Responds well to mulching and medium applications of fertilizer; prefers ph 5.0 to 5.5. Very little pruning is needed; adaptable to container and above ground planters; makes a good foundation plant or informal hedge with excellent foliage and flower contrast. Ideal for coastal regions and warmer parts of Piedmont. Propagated with semi-hardwood cuttings in late spring through the summer.
• Pests: Lace wing and spider mites can be a problem.

Claims

1. A new and distinct variety of Azalea plant named ‘Roblen’ as illustrated and described.