Yeah the Aussie species are all epiphytic, but are not usually seen with their roots exposed to the elements. Canaliculatum grows in rediculously harsh conditions, often in direct blazing hot sunlight, in areas that get much less rainfall than the other two native species. As a result, they always grow in a hollow tree, with the roots extending meters into the moist rotten heartwood of the host tree. Suave on the other hand seems to like moist elevated areas, often growing on dead trees with the roots creeping around under the bark and into any moist hollow spaces. Suave lacks pseudo bulbs so needs a constant moisture source. Madidum is the least fussy, growing anywhere from full sun to full shade, high or low elevation, on trees or on rocks. The biggest ones I've seen have been growing in elk horn ferns (platyceras I think, but that might be WAY off the mark)... These can withstand having some roots exposed to the elements, with the roots forming a nest to collect leaf litter. As Cattan said, these orchids have pendulous spikes, with small flowers. Madidum and suave are both beautifully fragrant.