The Distribution of Vireya Rhododendrons
The distribution of vireya rhododendrons in the wild is centred on the botanical region known as 'Malesia', an area of South East Asia encompassing the Malay Archipelago, the Philippines, Borneo, Indonesia and New Guinea and surrounding island groups. It is for this reason that vireyas are sometimes referred to as 'Malesian Rhododendrons', although nowadays this is not considered a strictly accurate term as a small number of the 300+ species in subgenus Vireya grow outside this region, extending as far as Taiwan in the north to Queensland, Australia in the south, and from India in the west to the Solomon Islands in the east.
The number of species recorded growing on each of the main islands
and island groups within the region is given in the table below.
Vireya Rhododendron Distribution
Click
here for a Distribution Map of the region (opens in new window).
Country |
|
No. of Species |
Nepal |
|
1 |
Bhutan |
|
1 |
India |
|
2 |
Myanmar |
|
3 |
China |
|
7 |
Taiwan |
|
1 |
Vietnam |
|
6 |
Thailand |
|
2 |
Malay Peninsula |
|
11 |
Sumatra |
|
22 |
Java |
|
7 |
Lesser Sunda Islands |
|
3 |
Borneo |
|
55 |
Philippines |
|
24 |
Sulawesi |
|
29 |
Maluku |
|
9 |
W. New Guinea |
|
113* |
Papua New Guinea |
|
87* |
Solomon Islands |
|
2 |
Australia |
|
2 |
|
|
|
|
* Island Total = 169 |
|
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Click here to go to the Vireya Species Database for listings of the species found in each country.
One misnomer commonly used when referring to vireyas is 'Tropical
Rhododendrons'. Whilst a few species, such as Rhododendron
zoelleri, are found growing at low altitude or even sea-level,
where a truly tropical climate prevails, the majority of vireya
species are to be found at higher elevations of between
1000m and 2500m. Here, in the cool montane forests, many species
grow as epiphytes high in the trees where there is more light
available to them than on the forest floor and where the morning
sunshine gives way to cloud cover, followed by rain later each
day.
Rhododendron ericoides Higher still, on more open
ground, other species, including the heath-like Rhododendron
ericoides (right), can be found growing terrestrially
at heights of up to 4000m. As night falls, the clouds disperse
leading to a rapid drop in temperature and above 2000m it
is not uncommon for frosts to form in some areas. Whilst in
a Temperate climate this could prove fatal, in their natural
habitat the vireyas are unaffected. At such latitudes there
is little seasonal variation, other than 'wet' and 'dry' seasons,
and daytime temperatures stay relatively constant throughout
the year allowing the plants to stay in active growth, which
in turn minimizes any potential frost damage. Plants grown
in Temperate climes, however, enter a dormant state for several
months each winter as both temperature and light levels fall,
consequently increasing the plants susceptibility.
Vireyas from the mid-altitudinal range are generally considered
easier to cultivate, requiring less heat than those from low-lying
areas, whilst replicating the growing conditions enjoyed by
the alpine species can be difficult to maintain throughout
the year.
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