Orchid Society of
Western Australia (Inc)
The Dendrobium bigibbum Complex
by Jim Brydie
Den bigibbum var bigibbum - Garrie Bromley
This surely has to be Australia's most beautiful native
orchid, but at the same time, Den. bigibbum has been the centre
of a confusing hotpot among taxonomists for a long, long time. Den.
bigibbum is a member of a small group of about 3 to 6 closely related
Dendrobium species in section Phalaenanthe. The section
gets its name for the fancied resemblance of their flowers to butterflies.
The reason I say 'about 3 to 6 species' is because the number depends
on whether you regard some as separate species, or just as variations
of Den bigibbum.
For many years the understanding was that there was one species (known
at the time as Den. phalaenopsis) that occurred in eastern Indonesia
on the islands near Timor, and that everything that occurred on the Australian
mainland, was Den bigibbum. However, work by Steve Clemesha in
1978 proposed that Den. phalaenopsis was the same as Den. bigibbum
and he proposed the name Den. bigibbum subspecies laratensis
for the Indonesian form.
Later, in 1989, after studying herbarium specimens in Europe, Mark Clements
(one of Australia's most eminent taxonomists) said that he believed that
the type specimen being used to define Den. phalaenopsis had actually
been collected in Queensland (which would make it a bigibbum),
but that Den. phalaenopsis and Den. bigibbum were none-the-less
valid and separate species.
In his opinion, at the time, Den. phalaenopsis occurred mainly
on the eastern side of the Great Dividing Range in northern Australia,
and that Den. bigibbum was found on the drier, western side of
the range as well as the Torres Strait islands and PNG. Clements also
considered that the species, known for many years as Den. bigibbum
variety compactum, was a third, separate, Australian species, and
gave it the name Dendrobium lithocola. The suggested changes left
the Indonesian species without a name, and he therefore formally described
it as Den. striaenopsis.
That meant that the bigibbum complex now comprised 4 separate but
very closely related species. (Den. bigibbum, Den. phalaenopsis, Den.
lithocola, and Den. striaenopsis)
Four populations is still 'sort of' where we stand today but there are
a few more twists in the story, with which we need to grapple. In 2006,
in his magnificent new edition of "Native Orchids of Australia",
among many other name changes, David Jones proposed a new genus name "Vappodes"
for the Phalaenanthe group, which made Dendrobium bigibbum
into Vappodes bigibba, and Den. phalaenopsis into Vappodes
phalaenopsis. I think this is a fantastic book, but the use of many
proposed new names like "Vappodes" makes it difficult
for hobby growers to use it without constant reference back to the index
against the older names with which they are more familiar. Luckily for
us, it seems hard to get a majority of taxonomists to agree on much at
all, so these changes are not widely accepted (..yet?). This leaves us
with much confusing variation among names for the same species.
Also in 2006, in the new edition of "Dendrobium and its Relatives",
Lavarack, Harris, and Stocker also recognise 4 separate populations but
they still regard the three Australian populations as varieties of Dendrobium
bigibbum, and the Indonesian one as Dendrobium strianopsis. This
is the nomenclature I favour, and their descriptions follow:
* Den. bigibbum variety bigibbum "occurs at low altitudes
on the Cape York peninsular, the Torres Strait islands, and in southern
New Guinea. It grows in hot conditions with an extremely dry winter, in
open forests and on rocks. The pseudobulbs may reach 120cm (over a metre)
but are usually 40 - 60 cm. The inflorescences can carry up to 20 flowers,
about 3 to 5cm diameter. They usually have a white spot in the lip."
* Den. bigibbum variety superbum (the one others call Den.
phalaenopsis) "occurs on the southern part of the Cape York peninsular
in open forests and dry scrubs often near beaches. It is an epiphyte (trees)
or lithophyte (rocks) in areas with a hot climate and extremely seasonal
rainfall. The pseudobulbs are similar to Den variety bigibbum
but often a little longer and stouter. The inflorescences are similar
but the flowers are larger, at 3 to 7cm across. They are less reflexed
than Den. var bigibbum, and they lack the white spot on
* Den. bigibbum variety compactum "occurs in a small
area near the coast of the wet tropics in northern Queensland. It grows
almost exclusively on rocks at an altitude of 250m. This area gets a little
more rain in winter, but there is still a rather drier period in winter
and spring. The pseudobulbs are commonly only 10 to 15cm long and 1 to
2cm thick. The flowers are similar to variety superbum but the inflorescence
* Den. striaenopsis "has been recorded only from the island
of Larat in the Tanimbar group south west of Irian Jaya. It grows on limestone
cliffs, and on trees, just above sea level, in a hot seasonal climate.
The pseudobulbs are long and slender, up to a metre long, and about 1cm
thick. The inflorescences are long and arching and carry up to 30 flowers.
The flowers are 4 to 7 cm across. Colour varies from deep purple, to white,
and bicoloured flowers with purple and white." (JB Many typical flowers
exhibit darker pinkish striations on a paler pink background. Hence the
name Den. striaenopsis).
Den bigibbum var. bigibbum - Den. bigibbum
var. superbum - Den. bigibbum var. compactum - Den. striaenopsis
For the pictures above, I selected rather good clones of each type, and
as you can see, in select clones there is sometimes little difference
between the flowers. Plants from the wild will exhibit a much wider range
of variation, especially in characteristics like the folding back (reflexing)
of the tips of the petals on Den variety bigibbum. In addition,
although the white lip spot is distinctive in this picture of Den variety
bigibbum, it varies dramatically and can be almost invisible in
some cases. As you might imagine, all this makes
it extremely hard to distinguish types when benched.
Probably an even bigger problem for us hobby growers (and even the judges)
however is that man has hybridised and line bred the different forms of
Den bigibbum between the varieties, and with just about every other
compatible species and hybrid, about one thousand times. This breeding
includes many where a parent is named as Den. phalaenopsis, which
is still a name accepted by the RHS hybrid registration board. Most of
what we just call hardcane Dendrobiums these days, are at least
75% Den bigibbum/phalaenopsis, sometime 90-95%, and look just like
huge Den bigibbums on steroids. Some look more modest and might
even just look like a very good Den bigibbum, despite the fact
they may even contain genes from a number of other species from Australia,
New Guinea, and the Pacific Islands. Sometimes they are benched or sold
as a Den bigibbum of one type or another, sometimes they themselves
are used as 'Den bigibbum' parents in creating what are purported
to be select forms of Den bigibbum. I am not saying that this applies
to all line bred Den bigibbums, just that it is impossible to tell.
Ian Chalmers, the Registrar of Judges at the OSNSW, recently wrote :
"Plants of the varieties of Dendrobium bigibbum exhibited are
difficult to differentiate. It would be a brave person to be certain at
monthly meetings or shows.
yes Den. phalaenopsis is recognised (by the RHS as a separate species).
However, unless we have the providence proving the origins of the plant,
it is better to treat them all as Dendrobium bigibbum complex. The RHS
register has two problems -
1. The registered parent is what the breeder thought it was at the time.
2. There has been a history of name changes between phalaenopsis and bigibbum
alternating over the years. So who knows what was really used?
None of this is simple. The more research I do the less comfortable I
am at differentiating between the cultivated varieties of Den. bigibbum
and between the species and the hybrids."
Just the same, no matter what they really are, these are all gorgeous
orchids, and very popular. At our last Kuringai meeting, when discussing
his lovely Den. bigibbum, which was selected Best Species of the
Evening, Garrie Bromley gave us a few tips on growing them. He grows his
plant in an enclosed but unheated glasshouse but it can be grown in a
shadehouse provided it is under a roof and can be given no water at all
during its winter rest period. After the flowers finish around May, Garrie
says they should be hung up high where there is good light and air movement,
and should be given no water at all until the new growths are well under
way in spring. Something like the culture regime we have been taught for
Catasetums in recent years.
Thanks to Jim Brydie for permission to reprint this thought-provoking