JARS v50n4 - Will All the White-Flowered Catawbienses Please Stand Up!

Will All the White-Flowered Catawbienses Please Stand Up!
Henry R. (Hank) Helm
Bainbridge Island, Washington

'Catawbiense Album' was a topic of discussion at our annual truss show a year ago and prompted me to do some research into white forms and hybrids of Rhododendron catawbiense . I looked at what a number of authors and taxonomists had to say and discovered an intriguing history of these perplexing plants that others may find as interesting as I did.
Controversy abounds over the origins of 'Catawbiense Album'. 'Catawbiense Album' (Waterer) was introduced and sold widely in the nursery trade early in this century and is listed by Salley and Greer (with one parent "unknown") with the statement: "Sometimes listed as a form of R. catawbiense , rather than a hybrid" (14). Gable was most certainly referring to 'Catawbiense Album' (Waterer) when he noted: "I do not agree with the classification that regards this as a clone of the species R. catawbiense " (13). Leach states that 'Catawbiense Album' is a hybrid and is undoubtedly talking about this plant (11). Bahnson calls 'Catawbiense Album' an English "ironclad" considered to be a hybrid (2). VanVeen and Greer, however, list this as a form of R. catawbiense (16, 9). Bowers goes both ways, calling this a form of R. catawbiense in one location and a hybrid in another (3).
In 1936 Powell Glass collected seven plants of R. catawbiense with white flowers from the wild (1). Apparently 'Catalgla' is a seedling from selfing a clone or crossing two of them. Gable recorded for 'Catawbiense Album' (Glass): "1939 Flowered 1943. Seedlings of a natural white form of the species discovered by the late Powell Glass of Lynchburg, Virginia, all of which have flowered white" (13). One of these is presumably the clone which was named 'Catalgla'. The Gable study group puts forth that "'Catalgla' (which is a shortened form of R. catawbiense album , Glass) came from seed of a white form of R. catawbiense found by Powell Glass in the mountains of Virginia" (13). Bowers states the parent of 'Catalgla' is named 'Glass White'*, which is the only reference I found naming one of the wild collected clones of Powell Glass (3).
'Catanea', apparently another seedling or selection of Powell Glass, was chosen by Gable, introduced by Nearing and described in Hybrids and Hybridizers as "a white flowering form of R. catawbiense , differing from other white forms in that the plant is shapely" (13). Cox disputes this and asserts that both 'Catalgla' and 'Catanea' have open habit and "yellowy" foliage (6). His opinion is that they are not genetically white and give only a percentage of white seedlings. 'Catalgla' is described by Salley and Greer as having pink buds opening white, while 'Catanea' is described as white and shapely (14).
Edmond Amateis crossed one of Powell Glass's white seedlings for five generations creating the cultivar 'Powell Glass' (1). Leach lists this plant as a selected form of R. catawbiense var. album grown and introduced in 1959 (11). This cultivar is reported to be a good white and "a promising breeding plant" by Cox (6). Salley and Greer state: "A fifth generation from seed, presumed to have stabilized so that seed from it would continue to produce pure white flowers. Selected from seed of 'Catalgla' (Gable). Attractive foliage on a vigorous, hardy plant" (14). They give 1962 as the date of introduction.
Leach asserts that the white species variant, R. catawbiense var. album , "is an extraordinarily fine and beautiful garden rhododendron, the first form of which was found by Powell Glass in Virginia" (11). 'Catalgla' and 'Catanea' are selected forms of R. catawbiense var. album , according to his list of rhododendron hybrids. Greer credits both Gable and Nearing for 'Catalgla' (9).
Chamberlain's revision of the genus describes the species R. catawbiense as "usually lilac-purple, with faint specs..." (4). He makes no mention of different colored forms or of any white forms, and he lists no R. catawbiense var. album , although earlier species lists include white along with colored forms.
Davidian describes the flowers of R. catawbiense as "...rose, lilac-purple, pink or white, with olive green spots" (7). He continues: "It is to be noted that a form with white flowers found by Powell Glass in Virginia has been known as R. catawbiense var. album ." He does not have this in his species list nor does he list this as a variety 1 in his description of the species.
The following are included by Spady in his Rhododendron Species Dictionary under R. catawbiense clones: 'Catalgla', 'Catanea', 'Catawbiense Album'?, 'La Bar's White', 'Powell Glass' and 'Virgin'* (15). Recognizing the difficulties with absolutes, Spady makes the following statement: "Where verification difficulties seemed to exist a ? is added to the definitions."
'Virgin' (an illegitimate name) is a form of R. catawbiense introduced by Weston Nurseries, and 'The Virgin' is a hybrid between a white form of R. catawbiense and a R. oreodoxa var. fargesii hybrid introduced by Abbott, according to Salley and Greer, though Leach lists 'The Virgin' as a synonym of 'Virgin' (11). 'La Bar's White' is noted by Bowers as being a pure white selection grown as a clone. He lists 'The Virgin' (Abbott) as white but makes no further comments about it (3). For the clone 'La Bar's White', Leach states "superior form of catawbiense var. album ...white in bud and flower, greenish-yellow markings in throat" (11).
Bahnson refers to several white forms of R. catawbiense including: 'Catalgla', 'Catanea', 'La Bar's White', 'Clark's White', 'Saura No. 5'* and 'Ken's Find'. He makes the following statement: "In contradistinction to 'Catalgla', 'La Bar's White' is pure white in bud and lacks color in the flower parts. It qualifies to be correctly termed R. catawbiense var. album ." (2). Leypoldt reports 'Saura No. 5' is to be in tissue culture, and she says it is white both in bud and flower (12). Bahnson's report noted this was a pure white, but at the time of this article he had not seen it in bud.
In summary, I believe we have a number of white clones of R. catawbiense . However, the rules of botanical nomenclature require that the name of a species or taxon of lower rank be published in accordance with the rules as to form, a type specimen must be in an herbarium and the description must be published in a work that is accessible to the public at least and to institutions with libraries accessible to botanists generally. In regards to R. catawbiense var. album , this has not been done. In my opinion, several of the clones collected and given names deserve to be included in this taxon if someone publishes a description. The question of which of the plants discussed and/or mentioned above would qualify for inclusion within it I will leave for others to debate. The rules for botanical nomenclature do state that the type specimen need not, and could not be representative of the full range of variety found within the group. 2
However, from the published history of these plants it would seem that 'Powell Glass', 'Catalgla', 'Catanea', 'Glass White', 'La Bar's White', 'Virgin' (illegitimate name), 'Clark's White', 'Ken's Find' and 'Saura No. 5' qualify as white-flowered clones of R. catawbiense . 'Catawbiense Album' (Waterer) is probably a hybrid.

1.  Amateis, E. Rh. Powell Glass. ARS Quart. Bull. 14:27;1960.
2.  Bahnson, R. White catawbasa recounting, new forms. J. Amer. Rhod. Soc.42:90-93; 1988.
3.  Bowers, C.G. Rhododendrons and azaleas, their origins, cultivation and development. New York, Macmillan; 1960.
4.  Chamberlain, D.F. Notes from the Royal Botanic Garden Edinburgh. Vol. 39, No. 2; 1982.
5.  Cox, P.A. The larger rhododendron species, revised edition. Portland, OR: Timber Press; 1990.
6.  Cox, P.A.; Cox, K.N.E. Encyclopedia of rhododendron hybrids. Portland, OR; Timber Press; 1988.
7.  Davidian, H.H. The rhododendron species, vol. Ill, elepidotes. Portland, OR: Timber Press; 1992.
8.  Gledhill, D. The names of plants, second edition. Cambridge: Cambridge University Press; 1985, 1989.
9.  Greer, H.E. Greer's guidebook to available rhododendrons, species & hybrids. Eugene, OR: Offshoot Publications; 1982.
10.  La Croix, I.F. Rhododendrons and azaleas. Devon: David & Charles Ltd.; 1973.
11.  Leach, D.G. Rhododendrons of the world. New York: Charles Scribner's Sons; 1961.
12.  Leypoldt, B. What's new on the Blue Ridge? J. Amer. Rhod. Soc. 48:86-88; 1994.
13.  Livingston, P.A.; West, F.H., editors. Hybrids and hybridizers, Newtown Square, PA: Harrowood Books; 1978.
14.  Salley, H.E.; Greer, H.E. Rhododendron Hybrids. Portland, OR: Timber Press; 1986.
15.  Spady, H.A. Rhododendron species dictionary (pamphlet); 1984.
16.  VanVeen, T. Rhododendrons in America. Portland, OR: Binford & Mort; 1980.

1 The botanical term is correctly "varietas," abbreviated "var."
2 Another option for botanists would be to give the white-flowered forms of R. catawbiense "forma" status. Plants at this level differ from the species as occasional individuals; they may or may not breed true.

* Name not registered.

Hank Helm, a member of the Kitsap County Chapter since 1974, lives and gardens on Bainbridge Island. He was awarded the Bronze Medal by his chapter. Currently he is part of the Western North American Rhododendron Species Project that is researching and mapping the Western rhododendron species.