Rhododendron ‘Mars’ • azalea

Rhododendron Rhododendron / Azalea  •  シャクナゲ / ツツジ  •  石楠花 / 躑躅    shakunage / tsutsuji

Rh. ‘Mars’ grows in many areas of the SJG, but the easiest to identify for a visitor is a group of 4 growing along the West Path between the second shortcut and yukimidoro lantern in the area V; they are maintained  at about 3′ tall, roughly rounded, but not too formal and blooming pink, usually in early May.


SJG • 5/6/13 – Rhododendron ‘Mars’ • azalea, Area V


SJG • 5/6/13 – Rhododendron ‘Mars’ • azalea, Area V – FLOWER and leaves

I just googled the plant, and it appears there are many different cultivars of ‘Mars’;  SJG has mostly one and the same cultivar throughout the garden, but I have no clue what cultivar  that might be… and it’s all dazzlingly mysterious and confusing.

Hirsutum lists it as ‘Rhododendron ‘Mars’ (not azalea), indicates its British breeding and shows a pic (click for yourself to see) of a typical huge rhodie with BIG flowers – for sure not the type we have, and I’m yet to sort through 70+ different cultivars  they cite (some with pics, and some without).

Googling azalea ‘mars’ returns multiple listings for ‘flame azalea’ addresses with house numbers, not plants…

And googling for Rhododendron ‘Mars’,  azalea returns mainly references to this blog 😦 – as if the rest of the world knew only about NON-azalea ‘Mars’…

This listing from Azalea Society of America gives some comfort (but not much) by saying:

[…] Formal registration of names for cultivated plants is now practiced internationally, but until fairly recently selection of names was rather haphazard. Names were applied to plants without considering whether they were already in use for another plant in the same genus. The name ‘Sunset’, for example, was given to at least nine different cultivars in genus Rhododendron, while ‘Pink Delight’ was used for at least seven. When such duplication occurs, the name does not serve its primary purpose, which is to identify each particular plant uniquely.

According to David Leach (Rhododendrons of the World, 1961), the first rhododendron species was introduced to Britain in 1656 (R. hirsutum from the European Alps). By 1800 only 12 species were known in cultivation (including R. canescens, R. periclymenoides, R. viscosum, R. catawbiense and R. maximum from North America, and R. ferrugineum and R. ponticum from Europe). The first known deliberate hybridizing of elepidotes occurred in 1810 when Michael Waterer crossed R. maximum with R. catawbiense. That is the time when name registration should have begun.

It was not until the early 1950s, however, that the first international effort was made to stabilize horticultural plant names. It soon expanded to include all cultivated plants. Presently, International Registration Authorities (IRAs) operate under regulations and recommendations formulated by representatives of agricultural, forestry, and horticultural products, under the auspices of the International Commission for the Nomenclature of Cultivated Plants. This body operates under authorization of the International Union of Biological Sciences which itself serves under the Inter national Council of Scientific Unions operating under the United Nations Educational, Scientific and Cultural Organizations (UNESCO).

In 1955 the Royal Horticultural Society (RHS) was asked to serve as the International Registration Authority (IRA) for the genus Rhododendron. Dr. H.R. Fletcher of the Royal Botanic Garden, Edinburgh, was the first international registrar for the genus. His initial duties were to compile and publish a list of all cultivated varieties of rhododendron and azalea names known up to that time. Source materials included catalogs, books, magazines, publications of plant societies, and lists submitted by growers. The American Rhododendron Society (ARS) was able to contribute substantially to this effort because one of the early objectives of the Society was to stabilize the naming of American rhododendron hybrids. As early as 1949, the ARS was formulating rules of nomenclature and seeking cooperation from growers. […]

 The registration application is divided into sections relating to: (1) parentage of the plant; (2) people associated with its hybridizing, growth, naming, commercial introduction, and registration; and (3) description of flowers, leaves, and growth characteristics. The form is accompanied by instructions illustrating typical flower, truss, and leaf shapes. Much of the descriptive material may be reported simply by checking appropriate boxes. Flower color is an important characteristic best described by reference to a color chart, preferably one of the editions of the RHS Colour Chart, but a name will not be rejected if the color is described in words rather than by reference to color numbers. All reasonable assistance will be given to those submitting applications. For example, presence of indumentum (either scales or woolly, plastered, or glandular hairs) is an important characteristic that may be difficult to describe. Upon request, the registrar will prepare this portion of the application if a typical leaf is enclosed. Remember that those who name plants have a responsibility to other growers as well as to the public to provide a permanent record for purposes of identification. Names and descriptions of all newly registered North American rhododendrons and azaleas are published quarterly by the ARS. The RHS publishes all additions to the Rhododendron Register annually. North Americans may request registration applications from me (phone and e-mail address given above). Others should write to the International Rhododendron Registrar, The Royal Horticultural Society’s Garden, Wisley, Woking, Surrey GU23 6QB, England.[…]

Something to ponder about during the next winter to maybe solve this ‘Mars’ puzzle – one factor to consider is a fact that many of our plants are as old as the garden (50 years+), so it is always possible that they are no longer sold commercially.


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