The display of the aerial roots of Cissus verticillata (syn. Cissus sicyoides) makes for an iconic photograph in Atlanta Botanical Garden’s Fuqua Conservatory. Easily ranked as one of the most impressive conservatories I’ve visited, it helped our recent trip start on a very positive note.
Known by a number of common names, including princess vine, millionaire vine and (with an appropriate adjective) curtain ivy, Cissus verticillata is native to much of the tropical Americas. I’ve not been able to track down any proven reasons why the species would evolve such extensive aerial roots, though some speculation can be made. One suggestion is access to additional water resources; please see the article “A Curtain of Roots” on page 27 of Gardenwise (Vol. 36, PDF), the magazine of the Singapore Botanical Garden. Whatever the reason(s), the aerial roots are also intriguing in terms of their high growth rate, measured under seemingly ideal conditions at about 8mm/hr (about an inch every 3 hours or so).
Additional photos of this grape relative, including images of leaves and fruit, are available from the Plants of Hawaii site (where the plant is non-native): Cissus verticillata.