26 July 2008

Caladenia decora - Esperance King Spider Orchid

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Caladenia decora - Esperance King Spider Orchid

If you want to be frustrated, then try to positively identify this orchid in the field, as it comes in all shapes, colors and sizes. Possibly a major problem, is it readily hybridises with two other large orchids in the district, Heberle's Spider Orchid, Caladenia heberleana and the Esperance White Spider Orchid, Caladenia longicauda subsp. crassa. As this has obviously been going on for a long time, you will find all sorts of genetic influences creating major and minor differences from the true form.

I went back to the original publication that reviewed the Caladendia genus, ie Nuytsia Vol 14 Numbers 1 and 2. There the major differences depicting this as a species is the clubbed portion of the sepals and petals being a maximum of 25 mm (1") in length and inflated (with some orchids the petals are not clubbed), whereas Caladenia heberleana is from 25 mm (1") to over 50 mm (2") and not inflated. There are other small differences, but they would more likely confuse than assist in this type of assessment. I stress that if you look, you will find all sorts of orchid variations that would be impossible to record, but if you use the differences above you will be reasonably close to finding a true Esperance Spider Orchid.

This orchid is common in the region, particularly around and above ephemeral swamps and granite outcrops in sandy soils, it flowers more prolifically after a summer bushfire, but is still well represented without one. Flowering time is usually from August to October.