Patent Publication Number: US-PP16184-P2

Title: Azalea plant named ‘Roblef’

Description:
Genus species:  Rhododendron  hybrid. 
   Varietal denomination: ‘Roblef’. 
   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 ‘Roblef’, was discovered by Robert Edward Lee in July, 1995 in Independence, La. ‘Roblef’ originated from a planned cross hybridization between two selected breeding lines in a controlled breeding program in Independence, La. The value of this new cultivar lies in its unique blooming period, bloom color, bloom form, bloom size, and growth habit. 
   Asexual propagation of the new plant by cuttings has been under Mr. Lee&#39;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 pink flower color Red-Purple Group 58B with dotting color Red Group 53C.   3. Large, single flowers ranging in size from 2¾″-3¼″ 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. 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 under story 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 dense and globose growth habit of a group of three gallon plants. 
     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. oldhamil 
               
                 
             
             
                 
                 
                 
               ‘Fourth of 
             
             
               Characteristic 
               ‘Roblef’ 
               ‘Karens’ 
               July’ 
               
                 R. oldhamil 
               
             
             
                 
             
           
          
             
               Height (Ma- 
               3-4′ 
               4-5′ 
               8-10′ 
               8-10′ 
             
             
               ture) 
             
             
               Width (Mature) 
               3-4′ 
               4-5′ 
               6-7′ 
               6-7′ 
             
             
               Flower Diame- 
               2¾-3¼″ 
               1½-2″ 
               1¾-2¼″ 
               1¾-2¼″ 
             
             
               ter 
             
             
               Flower Form 
               Single 
               Single 
               Single 
               Single 
             
             
               Flower Color 
               Red-Purple 
               Red-Purple 
               Red G. 39A 
               Red G. 39A 
             
             
                 
               G. 58B 
               G.61B 
             
             
               Flowers per 
               2-4 
               1-4 
               2-4 
               2-4 
             
             
               Terminal 
             
             
               Bloom Period 
               April 
               May 
                 
               Mid-May &gt; 
             
             
                 
                 
                 
                 
               Mid-June 
             
             
               ″ 
               Early July &gt; 
                 
               Late June &gt; 
               Sporadic &gt; 
             
             
                 
               Frost 
                 
               Frost 
               summer 
             
             
               Petal Number 
               5 
               5 
               5 
               5 
             
             
               Hardy Zone 
               7 
               6 
               7 
               8 
             
             
               Stamen Num- 
               6-7 
               10 
               7-10 
               7-10 
             
             
               ber 
             
             
               Stamen Type 
               Non-Petaloid 
               Non-Petaloid 
               Non-Petaloid 
               Non-Petaloid 
             
             
                 
             
          
         
       
     
   
   The female, or seed parent, of ‘Roblef’ is the Azalea ‘Karens’; a deep reddish purple, single, mid-season blooming, medium height grower. ‘Karens’ is an unpatented Azalea introduced by Verkades Nursery in 1979 and was the result of a cross between the Kurume Hybrid ‘Hino de Giri’ (unpatented) and a plant of the species  Rhododendron poukhanense.    
   The male, or pollen, parent of ‘Roblef’ is the Azalea  Rhododendron oldhamii  ‘Fourth of July’ (unpatented). ‘Roblef’ differs from ‘Fourth of July’ primarily in flower color. 
   Robert Edward Lee&#39;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 bloomig 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:   Botanical:  Rhododendron  hybrid ‘Roblef’.   Form: Dense and rounded.   Height: 3-4′.   Width: 3-4′.   Growth habit: 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 2 feet and a spread of 2 feet. The growth rate is normally about 6 to 8″ per year; the plant reaches a height of 3 to 4′ at maturity while maintaining a dense habit due to the abundant branch development.   Foliage: Alternate, simple, evergreen, pubescent, elliptic to narrowly elliptic, and varying in size from 2¼″ to 2⅞″ long and ¾″ to 1″ wide. The margins are entire, with a petiole ¼″ to ⅜″ 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, dull and slightly pubescent and the underside is Yellow-Green Group 146B, matte, and pubescent. The upper end of the mid-rib and veins is 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.   

   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 4″ for a plant in full sun and about 6″ when grown in shade. This growth should not be trimmed since it will produce flowers starting in early 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, petioles, and lower end of the mid-ribs are Greyed-Purple Group 184A and densely clothed with spreading white glandular hairs. As the stems mature they become Yellow-Green Group 152B and by the second growing season they are 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 200A. The buds are borne in clusters of 2 to 4, 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 ½″ to ⅝″ long, pubescent, and Red Group 47A. The calyx is ⅜″ to ½″ 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-Purple Group 58B.   Flowers: Perfect, single, Red-Purple Group 58B (upper surface and under surface), glabrous, open funnel shaped, 2¾″ to 3¼″ in diameter by 1¾″ to 2¼″ in depth, borne on current season&#39;s growth, non-fragrant; they last on the plant in the garden 5 to 6 days. There are five true petals which are fused at the base, elliptic, and have wavy margins. These petals are 1¾″ to 2¼″ 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 6 to 7 non-petaloid stamens which are 1¼″ to 1¾″ long. The filaments are Red Group 53D, the anthers are Red-Purple Group 59A, and the pollen matures to Yellow Group 11B. The pistil is single, non-petaloid, 1⅝″ to 2″ long and Red Group 53C. The ovary is densely glandular-setose and have 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 147A, 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 early 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.