I think I saw this question in a forum recently. And the answer is: she’s wearing a crinoline petticoat. It adds fullness to skirts and dresses without the aid of underframing or boning.
In the 1950′s, rustling crinolines to fill out full-skirted dresses were all the rage (poodle skirts, anyone?). Nowadays, it’s mainly seen in the bridal and formal market (prom dresses). For her first solo collection, fashion designer Vivienne Westwood looked to the crinoline for inspiration. The collection, titled Mini Crini, featured shorter crinoline skirts with more flexible plastic hoops.
The crinoline is also used in costuming, especially square dance, can-can and national dress – and of course by vintage enthusiasts!!
Where to buy Crinoline Petticoats
Secrets in Lace has an abundance of these on their site, in Curvy Woman sizes as well as standard sizes. There are three fine quality soft chiffon styles. They’re beautiful and often featured with contrasting trim!