Rhododendron rootstock named ‘Rhodunter 48’

- Inkarho GmbH

A new and distinct Rhododendron hybrid plant used as a rootstock or flowering shrub that exhibits hardy and vigorous growth.

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Botanical classification: Rhododendron hybrid.

Varietal denomination: ‘Rhodunter 48’.


The present invention comprises a new and distinct cultivar of Rhododendron hybrid used as a flowering shrub or rootstock known by the varietal name ‘Rhodunter 48’. The new variety was discovered in Ahrensburg, Germany. The new variety is the result of a planned breeding program between an unpatented and unnamed plant of Rhododendron fortunei (female parent)×cv. ‘Cunningham's White’ (unpatented male parent). The new variety exhibits matroclinal morphological features. ‘Rhodunter 48’ exhibits distinct but similar leaf venation to both parents, as well as similarities in color and shape. The new variety has been trial and field tested and has been found to retain its distinctive characteristics and remain true to type through successive propagations.


The accompanying photographic drawings illustrate the new cultivar, with the color being as nearly true as is possible with color illustrations of this type.

FIG. 1 shows a close-up view of the flowers of the new variety; and

FIG. 2 shows the new variety grown to a flowering plant.


The following detailed description sets forth the characteristics of the new cultivar. The data which defines these characteristics were collected by asexual reproductions performed using tissue culture medium for shoot multiplication of Rhododendron species and which were carried out in Ahrensburg, Germany. The color readings were taken in natural daylight. The field-grown plants were five years old when described (unless indicated otherwise). The soil was a sandy loam mixed with peat. Color references are primarily to The R.H.S. Colour Chart of The Royal Horticultural Society of London.


  • Type: Evergreen shrub.
  • Use: Flowering shrub or rootstock.
  • Soil: Sandy loam.
  • Light: Full.
  • Fruit bearing: Very low.
  • Crop time: 1.5 years is required to achieve finished product size that is ready for use as a rootstock or 4 years for use as a flowering shrub.
  • Dimensions at crop time (3 years after grafting. Dimensions depend on the vigor of the scion cultivar):
      • Height.—50 cm.
      • Width.—40 cm.
  • Vigor: 120% of standard using ‘Nova Zembla’ (unpatented) as the standard.
  • Habit: Erect.
  • Hardiness: USDA zone 6a.
  • Rooting habit: Compact root bales.
  • Time to initiate roots: 3 months at 22-25° C. for softwood cuttings.
  • Disease and pest resistance: No observation made to date.
  • Trunk (at 4 years):
      • Diameter.—3 cm.
      • Height.—5 cm above soil.
      • Bark color.—Surface: Year 1: 147A. Year 2: 144A to 175A. Year 3: 175A. Year 4: 177B to 197B to 197C. Flesh: 157B.
      • Lenticels.—Inconspicous.
  • Branches:
      • Color.—Surface: Year 1: 147A. Year 2: 144A to 175A. Year 3: 175A. Year 4: 177B to 197B to 197C. Flesh: 157B.
      • Length (at one year).—22 cm.
      • Base diameter (at one year).—9 mm.
      • Texture.—Hard.
      • Internode length.—1-2 cm.
      • Branching angle at emergence.—45° angle.
      • Habit.—Compact.
      • Pubescence.—Absent.
      • Branch lenticels.—Inconspicous.
  • Leaves:
      • Arrangement.—Alternate.
      • Length.—20 cm maximum.
      • Width.—7.5 cm maximum.
      • Shape.—Oblanceolate.
      • Apex.—Truncated.
      • Base.—Triangular.
      • Color.—Adaxial: 147A. Abaxial: 147C.
      • Surface.—Adaxial: Glabrous. Abaxial: Glabrous.
      • Margins.—Entire.
      • Division.—Undivided.
      • Petiole.—Length: 2 cm. Width: 3-4 mm. Color: Between 144A and 166B. Surface: Glabrous.
      • Leaf stipules.—Sessile.
      • Leaf pubescence.—Absent.
      • Venation pattern.—Feather-veined.
      • Vein color.—Adaxial: 144A. Abaxial: 145C.
      • Leaf texture.—Hard.
      • Leaf appearance.—Typical Rhododendron leaf.
  • Fruit: Fruits (capsules) are usually absent due to self-sterility or incompability with other Rhododendrons. When present, the seed color is 164B.
  • Flower:
      • Arrangement.—Single.
      • Shape.—Widely funnel-shaped.
      • Bud.—Shape: Oblong; Ellipsoid. Width: 20 mm. Length: 40 mm. Color: Closed: 186B. Before bursting: 65B. Time of bloom: At 2 years old. Lastingness of bloom: 21 days.
      • Diameter.—8 cm.
      • Depth.—20 mm.
      • Bloom quantity.—11-15 per truss.
  • Petal:
      • Shape.—Fused; the corolla has a wide funnel shape.
      • Number.—7.
      • Length.—45-55 mm.
      • Width of corolla.—70-80 mm.
      • Apex.—Round.
      • Margin.—Undulate.
      • Color (when fully open).—Upper surface: 158B. Lower surface: 159C.
      • Peduncle.—Length: 4 cm. Width: 2 mm. Surface: Glabrous. Color: Upper surface: 179B. Lower surface: 144C.
  • Sepals: Not present.
  • Petaloids: Not present.
  • Natural flowering season: Beginning of May through the end of May.
  • Fragrance: Rhododendron fortunei-like.


  • Stamens:
      • Number.—14.
      • Length.—30 mm.
      • Color.—150D.
  • Anthers:
      • Shape.—Normal Rhododendron type.
      • Color.—161D.
      • Length.—25 mm.
      • Width.—1 mm.
      • Amount of pollen.—Medium.
      • Color of pollen.—150D.
      • Stigma color.—145A.
  • Pistil:
      • Length.—5 cm.
      • Number.—1.
  • Style:
      • Color.—150C.
      • Form.—Filiform.
      • Length.—45 mm.
      • Width.—1 mm.
  • Ovaries:
      • Length.—5 mm.
      • Width.—3 mm.
      • Color.—137C.
      • Position.—Superior.


1. A new and distinct variety of Rhododendron hybrid plant as illustrated and described.

Patent History
Patent number: PP15967
Type: Grant
Filed: Oct 11, 2002
Date of Patent: Sep 20, 2005
Patent Publication Number: 20040073980
Assignee: Inkarho GmbH (Bad Zwischenahn)
Inventors: Walter Preil (Ammersbek), Rainer Ebbinghaus (Ahrensburg)
Primary Examiner: Kent Bell
Attorney: Webb Ziesenheim Logsdon Orkin & Hanson, P.C.
Application Number: 10/270,093
Current U.S. Class: Azalea Or Rhododendron (PLT/238)