Lone orange blossom in the Victorian rainforest
To end the year (my eighth-and-a-bit year of Talking Plants), the story of a plant bearing small white blossoms with a citrous bouquet, and clinging desperately to the trunks of a few rainforest trees in East Gippsland.
The Orange Blossom Orchid, Sarcochilus falcatus, is confirmed as a native in Victoria by a small number of plants attached to rainforest trees in Howe Range, east of Mallacoota in the State's far east. Their location is not far from NSW, where the species is not uncommon along the coastal strip right up to southern Queensland and (thanks David Banks, my Sydney colleague, for confirming this big disjunction) also around the Atherton Tableland and Mt Lewis, up Cairns way.
You'll see other records for Victoria, some no longer current. These days it is extremely rare in Victoria due 'to clearing of its habitat for agriculture', and even its meagre mapped distribution in East Gippsland may overstate its true range due to a little assisted dispersal by local humans.
For example, according to Gary Backhouse, Bill Kosky, Dean Rouse and James Turner, in their 2016 e-book, Bush Gems: A Guide to the Wild Orchids of Victoria, Australia a remnant population near Cann River was lost during a flood in the 1980s. Whether this population existed pre-European settlement is disputed, by some.
Over the border Orange Blossom Orchid usually grows on the trunks of Blackwood (Acacia melanoxylon), or rocks. In Victoria, according to VicFlora, it is more often found on Eucryphia moorei, the Eastern Leatherwood but it is also (Gary Backhouse and Jeff Jeanes The Orchids of Victoria; 1995) found on Blackwood, Lilly Pilly (Acmena smithii) and, apparently after plants fall from tree trunks, on rocks and tree ferns.
Tony Bishop (Field Guide to the Orchids of New South Wales and Victoria, 2nd edn; 2000) illustrates three growth forms from New South Wales with variously coloured stripes on the lip and odd odors, including one 'resembling freshly cut potatoes'. In Bush Gems the Victorian populations are said to include a mountain growth form with purple markings on the chin-like protrusion (the spur) of the winged 'lip' (labellum). Or perhaps a lowland form without the markings, depending on your altitudinal perspective.
Either way, these and other variants may, or may not, require taxonomic recognition - as might other variants with variously coloured and shaped floral parts. I couldn't see any unusual purple tints on this home-grown specimen other than stripes on the back of the flanking petals (and the orange blossom purfume didn't seem to be infused with potato).
There are 20 or so species of Sarcochilus, collectively called the butterfly orchids, with 16 species in Australia and New Caledonia (there are no 'true' Sarcochilus in New Guinea according to David Banks). We have only two in Victoria - Sarcochilus falcatus and Sarcochilus australis. The other species - australis - has flowers with narrow, green or brown, outer segments (not broad and white as in falcatus).
These two species are unusual in the south-east corner of Australia. Of the nearly 370 to 400 species of orchid known from Victoria (of which 327 are formally named and described) there are only another two that grow on trees or rocks (ephiphytic or epilithic, respectively) - the rest are ephemeral ground orchids with underground tubers.
The pictures in this post are from a cultivated plant purchased recently at the Australian Native Orchid Society annual show, and flowering at my home in early October. Its origin in nature is unknown (to me).