I need help identifying these vines cascading in this picture.

The plant is not clear enough but what a beautiful spot!!

You might try contacting the designers. Here is the site where your photo is featured. It is in Vietnam.
http://www.dezeen.com/2015/07/...

What a beautiful place, and made even more so since it features a plumeria

We do need more detailed photos but the plant reminds me of Microgramma I found growing in the rain forests of Brazil. When they have no climbing support they cascade like that..
https://www.google.be/search?q...

Possibly Tillandsia Usneoides.

https://www.flickr.com/photos/...

Possibly Tillandsia Usneoides.

https://www.flickr.com/photos/...

https://www.bing.com/images/se...

This site seems to have the name...Vernonia elliptica.

https://uk.pinterest.com/pin/4...

https://www.google.co.uk/searc...

Since one of the photos is the identical shot, I believe you nailed it, Silversurfer! What a neat plant!

porkpal said:Since one of the photos is the identical shot, I believe you nailed it, Silversurfer! What a neat plant!

I wonder if tpierce ever came back to see if the question got an answer?

Vernonia elaeagnifolia

Agree,... it is very popular trailing plant creating waterfall effect, or as a screen,
Here we call it "Lee Kuan Yew" plant, the accepted name according to catalogue of live is Tarlmounia elliptica, with Vernonia elliptica as synonym, V. elaeagnifolia is also a synonym.
Vernonia elliptica