Anglesea is very fortunate to have a number of Spider Orchids growing in the district, ranging in size from the Caladenia parva Small Spider Orchid, mostly shorter than 15 cm, to the Caladenia venusta Large White Spider Orchid that can grow to 60 cm in height.
They are called Spider Orchids because of their long, filamentous sepals and petals that could be said to resemble spiders’ legs. These segments often end in fine, elongated tips, which may be conspicuously clubbed or covered densely with dark-coloured glandular hairs. They all have a single hairy basal leaf, and a hairy stem.
We have nine different species, and a number of recognized hybrid spider orchids. However, two of these species are exceptionally rare, and are therefore unlikely to be seen; these are Caladenia capillata Daddy Long Legs (I am still waiting to find it in our district) and the Caladenia valida, Robust Spider Orchid listed as endangered in Victoria. Three more of our Spider Orchids, Caladenia australis Southern Spider Orchid, Caladenia oenochila Red-lipped Spider Orchid and the Caladenia venusta Large White Spider Orchid are listed on the Victorian Threatened Species List.
As you walk the bush tracks and reserves at the present time you are likely to find some of these spider orchids that have just started to open their flowers during the past few weeks. These are the Caladenia cardiochila Thick-lip Spider or Heart-lip Spider Orchid, C. clavigera Plain-lip Spider Orchid, C. oenochila Red-lipped Spider Orchid, and the C. parva Small Spider Orchid.
Heart-lip Spider Orchid
Plain-lip Spider Orchid
C. venusta The Large White Spider Orchid has been teasing us by showing the tips of its red sepals and petals at the top of its bud and is ready to burst open to show its spectacular large flower, while some of the other species are still to appear. The cold, dry weather this year has meant that the orchids are slower to flower than is usual and many are very small.
Generally, the different species are easy to distinguish. You will find their photographs and descriptions in Orchids of the Anglesea District available from ANGAIR or local bookshops.
Spider orchids release a perfume that mimics a fertile female wasp, luring male insects to the flower. Overcome by the scent the males are tricked into attempting to mate with the flower. During their futile attempts they pick up the pollinia (pollen), which is then transferred to another flower when they repeat the visit. Thus pollination will occur – the male insects get no reward for their endeavours.
Almost all Spider orchids reproduce solely from seed, so pollination is an extremely important process. The plant produces a replacement tuber each season, but from our observations, some of our colonies are becoming smaller. Hopefully the tubers are just dormant underground, and are awaiting better weather conditions or indeed fire to stimulate their growth.
Of course, there are many other orchid species to see in the field in spring, and the onset of our Sun Orchids will surely tempt orchid lovers to venture out in the next few months. We hope you can find time to enjoy them.