Rhododendron saxifragoides
and its hybrids

Rhododendron saxifragoides
at the Royal Botanic Garden Edinburgh

First described by J. J. Smith in 1915 from material collected in New Guinea, Rhododendron saxifragoides is an alpine vireya species found growing terrestrially in boggy conditions, within grassland or forest glades, at an altitude of between 3200 and 4000 metres (10,400-13,000 feet).

Endemic to the island of New Guinea, Rhododendron saxifragoides can be found across the Main Range from Mt. Carstensz to the Oranje Mts, Mt. Wilhelmina and Lake Habbema, on to the Hagen Range, Mt. Giluwe and Mt. Sugarloaf in the Western and Southern Highlands.

Locally abundant, the species is distinctive in forming clusters of linear-lanceolate leaves up to 3.4cm long by 0.7cm wide (1 1/4" x 1/4") at the ends of branchlets that combine to form dense mats or tussocks up to 15cm (6") high. Apart from this cushion-forming habit, Rhododendron saxifragoides is also unusual in that it develops a long taproot rather than the mass of shallow fibrous roots more commonly associated with members of Subgenus Vireya. This adaptation enables the plant to penetrate crevices in the rocky outcrops often found in its natural environment.

Rhododendron saxifragoides
collected at 3,900 metres on Mt.Giluwe, Papua New Guinea.
Note the long taproot.

Between August and December the plants put on a display of red to pink, 3.5cm (1 1/3") tubular-cylindrical flowers. Usually solitary, although occasionally in pairs, the flowers are held aloft on long reddish pedicels up to 9cm (3 1/2") in length.

Rhododendron saxifragoides is scarce in cultivation due mainly to the difficulties faced by growers in replicating the natural environment of this species, i.e. maintaining boggy conditions in combination with the high light levels it is accustomed to enjoying at high altitude throughout the year.

Whilst these drawbacks perhaps mean Rhododendron saxifragoides will remain an enthusiasts' plant, there are a number of hybrids available that bear many of the desirable traits of this species, such as the long stalked, nodding flowers, but are considerably easier to please in cultivation as well as being much more widely available. A list of current hybrids with Rhododendron saxifragoides in their parentage is given in the following table:

Foremost among these are the 'Saxon' range of hybrids, bred by Os Blumhardt in New Zealand, most notably R.'Saxon Glow' and R.'Saxon Blush' which, given suitable cultural conditions, will regularly cover themselves in flower as evidenced by the photographs below.

Rhododendron 'Saxon Glow'

Rhododendron 'Saxon Blush'

The parentage of these two hybrids is identical: R. 'Hot Tropic' x R. saxifragoides. The hybrid R. 'Hot Tropic' came about when R. 'Tropic Glow' was selfed by Os Blumhardt in 1976 and later registered by him in 1990. The original cross between the species R.laetum and R. zoelleri that first gave rise to R. 'Tropic Glow' was made by Tom Lelliott in Australia (date unknown) and registered by Os Blumhardt in 1984.

Rhododendron 'Hot Tropic'	Rhododendron 'Tropic Glow'
Rhododendron laetum	Rhododendron zoelleri

As can be seen from the above pictures, the outcome of the crosses between R.laetum and R. zoelleri and the selfing of R. 'Tropic Glow' were perhaps predictable to an extent but the addition of R. saxifragoides into the equation produced a dramatic dwarfing effect in both leaf size and overall habit of the resultant hybrids. Indeed, the R. saxifragoides influence is sufficiently dominant to impose itself at all levels, most notably in the appearance of the flowers which are held high on long pedicels in a manner reminiscent of their alpine ancestor. Another most welcome feature of these hybrids is their compact and well-branched habit, producing well-foliaged plants from the base upwards, going a long way towards countering claims by some that vireyas are overly 'leggy'.

The hybrids of R. saxifragoides produced to date have mostly been in shades of red or pink, however, this small species seemingly offers exciting potential for the future and it is to be hoped that, over time, hybridists will be able to extend the colour range whilst retaining the many other desirable qualities.

Rhododendron 'Saxon Glow'