QBARS - v22n4 Studies on Glenn Dale Azaleas at the National Arboretum

Studies On Glenn Dale Azaleas At The National Arboretum
Dr. Roy Magruder - Washington, D. C.

In the Addendum to Frederic P. Lee's article in the April 1968 Quarterly Bulletin of the ARS on B. Y. Morrison and his Azaleas, mention was made of some of the work the writer is doing at the National Arboretum. Having observed superficially for years the collection of Glenn Dale azaleas in the Morrison Garden and the adjacent Azalea Loop (to the north of the garden) at the National Arboretum, the writer after his retirement from the U.S. Department of Agriculture, decided he would spend some of his time getting better acquainted with this very diverse group of varieties.
In a conference with the present director it was agreed that there were a number of jobs needed on which help would be appreciated. An appointment as Collaborator was made and an assignment to an office adjacent to the lower floor of the herbarium where space was available for work on specimens from the herbarium and on those collected fresh.
The size and complexity of the task was emphasized by a study of U. S. Department of Agriculture, Agricultural Monograph No. 20, issued October 1933 (now out of print) which contains names and short descriptions for 454 varieties. A survey of available materials and information not included in Monograph 20, indicated need of work, which has been undertaken, on the following numbered items:

  1. Compile lists of sources (commercial, in botanical gardens and arboretums, and in private collections) for all Glenn Dale varieties. All recipients of the official distributions have been contacted, and lists obtained of varieties still living and identifiable.
  2. Assemble a complete collection of Glenn Dale varieties. Due to losses from one cause or another, the Arboretum collection was incomplete, but all the varieties officially distributed have now been located and should be collected during 1968. It will be several years before the new arrivals can be verified as to trueness to name. The official distributions of Glenn Dales were made in 1942, 1948, 1949, 1950, 1951, 1952, 1953 and 1954.
  3. Develop an outline containing enough taxonomic or descriptive characters to enable the construction of a key separating all of the varieties available. The descriptions contained in Monograph No. 20 were not adequate for this purpose and the needed information was not available. An effort is being made to use a system of recording observations on both plant and flower characters that can be used in IBM equipment. Considerable progress has been made on this problem but it will be several years before the data can be secured for all varieties.
  4. Develop lists of recommended varieties for the main color groups by season of bloom, height of plant, degree of evergreeness, color of winter foliage, etc.
  5. Identify, if possible, all mislabeled plants of Glenn Dales in the National Arboretum plantings.

Progress Reports
Referring to the Addendum questions in the April 1968 above mentioned article, the following information supplants or supplements that supplied by Frederic P. Lee.
QUESTION 1 . Have any of the clones disappeared?
Answer : All of the varieties officially distributed should be in the Arboretum Collection during 1968. So far as we know now, there is no other complete collection.
QUESTION 2. Are there some named varieties of Glenn Dales that were never actually distributed?
Answer : According to the records of the Plant Introduction Station at Glenn Dale, Md., the following varieties listed in USDA Monograph No. 20 were never formally distributed to the trade (to nurserymen): 'Alexandria', 'Aries', 'Barchester', 'Berceuse', 'Candlelight', 'Caress', 'Etna', 'Fenelon', 'Horus', 'Naxos', 'Orpheus', 'Pontiff', 'Romance' and 'Touchstone'.  There are, however, plants of 'Touchstone' and 'Fenelon' in the plantings at the National Arboretum.  We should like to know the location of any of the other above mentioned varieties that may have been distributed after the formal distributions were made.
QUESTIONS 3, 4, 5 will be discussed in later reports as our study progresses to the point where conclusions can be drawn or opinions supported by facts and experience.

Reader Contributions
The writer would greatly appreciate, for our lists of Sources for Glenn Dale Varieties, the names and addresses of commercial nurserymen, botanical gardens or arboreta, or private collectors who are growing Glenn Dale varieties of azaleas.
It is hoped that readers will respond to the Editor's invitation to send comments on the performance of Glenn Dale varieties under different climatic and soil conditions. Information of this kind will be helpful to all in making judgments as to regional adaptation of Glenn Dale varieties.

Pictures of the five Glenn Dale azaleas were to have accompanied the article by the late Frederic P. Lee, in the April, 1968 Bulletin, entitled " B. Y. Morrison and his Azaleas." They arrived too late for that issue, and it is fitting that they be used with Dr. Magruder's article. - Ed.

R. 'Quakeress' R. 'Cygnet'
Fig. 58.  Glenn Dale Azalea 'Quakeress'.
Erect to somewhat spreading, to 6 ft., leaves
large somewhat roughened, hairy.  Flowers
2 to 7 in a head, to 2¾ ins. across, white
with flakes of Bishop's Purple, very unequal
in different flowers, margins sinuate.  Mid-
to late Apr.
U. S. D. A. Photo
Fig. 59.  Glenn Dale Azalea 'Cygnet'. Very
dense and twiggy, but possibly to 4 ft.
Flowers 1½ in. across, very freely produced
to make sheets of bloom, white with pale
yellow blotch.  Early to mid-April.
U. S. D. A. Photo
R. 'Martha Hitchcock' R. 'Helen Gunning'
Fig.60.  Glenn Dale Azalea 'Martha Hitchcock'.
Broad, spreading, probably to 4 ft.  Flowers
1 to 3 in a head, 3 ins. across, white
margined with magenta. Strongly growing
shoots usually produce self-colored flowers.
Do not remove, as laterals give flowers with
correct patter thereafter.  Early to mid-May.
U. S. D. A. Photo
Fig. 61.  Glen Dale Azalea 'Helen Gunning'.
Bush habit broad, spreading, probably
to 5 ft. in height, leaves medium green.
Flowers 1 to 2 in head, 2½ ins. across,
flat face, ruffled margins, white center,
margins Tyrian Pink.  Mid-May.
U. S. D. A. Photo
R. 'Louise Dowdle'
Fig. 62. Glenn Dale Azalea 'Louise Dowdle'.
Broad to wide spreading, densely twiggy
in time, but up to 5 ft.  Flowers very freely
produced, 1 to 3 in a head, 3 ins. across,
brilliant Tyrian Pink, with showy blotch
of Tyrian Rose. Mid- to late May.
U. S. D. A. Photo