Rhododendron viriosum (syn. Rhododendron lochiae)

Rhododendron viriosum is a shrub to about 3 metres tall by about 1 to 2 metres wide.

It is found in tropical North Queensland, known from a few locations as far south as Herberton and Babinda-area (south of Cairns) – extending northwards to Gordonvale; then found west of Mossman and Port Douglas and then further north west of Cape Tribulation and south of Cooktown. R. lochiae is found on three peaks Bell Peak, Mt Bartlefrere and Mt Bellenden.

It is typically found in tropical rainforest including cloud forests and open rocky areas which adjoin such habitat, esepcially at high altitudes.

It tends to be semi-epiphytic – growing on rock shelves where it places its roots into cracks, as well as an epiphyte on other trees (similar to some fig-species).

A note is made here to account for an unusual taxonomic ‘dog’s breakfast’. Point form may be easier:

• Plants going by the name Rhododendron lochiae became popular in cultivation.
• It was then found that cultivated plants differed to the “type” specimen – that is, the herbarium on which the description of the species is based.
• It was revealed that there are possibly two species in this part of tropical Queensland and they differ in the size and curvature of the flowers. It appeared that R. lochiae should be applied to the species with the longer and curved flowers.
• The Late Lyndley Craven (Botanist) argued, in 1996, that the name of R. lochiae should be kept in use for the species that was abundant in horticulture, to save everyone much confusion, and that a new “type” specimen should be created. In addition, the second species that had the name of R. lochiae applied originally, could be changed to R. notiale. However, this was rejected by the governors of  International Code of Botanical Nomenclature.
• Hence, the common horticultural species was given a new name, R. viriosum, and it was insisted that R. lochiae (which was not yet common in horticulture) be kept for the “type” specimen and other plants matching that specimen.

However, the “get-out-jail-card” here is that the Australian Plant Census has decided to recognise R. lochiae as the only species currently in Australia. So…we think this means we can still use the name for garden plants.

It is worth noting, however, that recent investigations have indicated that two distinct species do indeed exist i.e., Rhododendron lochiae (as per the type specimen) and Rhododendron viriosum (which is commonly cultivated). Do note that both species are described in the Australian Tropical Plants Online Key (see references below).

R. viriosum is found north of the Barron River in several geographic locations as far North as Mt Finnigan and as far west as the Windsor Tablelands.

The species are differentiated by R. lochiae having a distinct curved tubular corolla and R. viriosum the shorter and straight tubular corolla.

Rhododendron species tend to have simple and whorled leaves. In this species, they are in whorls or false-whorls, of 3 to 5, to 11 cm long and 7 cm wide, usually elliptic to ovate; cracking if they are bent, mid-green in colour with the underside marker by dark scales.

Rhododendron have 5-merous flowers. In this species, flowers are tubular with 5-lobes (trumpet-like), up to 5 cm long by 2.5 cm wide at the tips produced in umbels of up to 7 which tend to hand penduously; deep red-pink in colour; with 10 stamens on the inside of the tube; produced mostly from spring through to autumn.

The fruit is a capsule to 3 cm long and narrow.