CELIA BIRTWELL -- the British printmaker behind the legendary Ossie Clark -- is bringing her style to the States with a line of dresses and blouses for Express, the store's first-ever designer collaboration. And you'll want to mark the line's April 7 debut date: When Birtwell did a similar cheap-chic collection for Topshop in Britain, it immediately sold out.

Birtwell's romantic designs helped skyrocket the career of Clark, her late ex-husband and the designer who dressed Twiggy and Marianne Faithfull in the late 1960s. In February, Clark's label was revived on the London runways, but it lacked Birtwell's participation -- and critical acclaim.

The Celia Birtwell for Express collection is true to Clark's style: fluid and sheer, with the flora and fauna that are Birtwell trademarks. A breezy red blouse is covered with Lily, one of her best-known prints. Floating Daisy, her famous psychedelic swirls, appears throughout the line.

Clark often used patchwork, a tradition Birtwell continues. The bodice of one dress is splashed with bold flowers, and its billowy sleeves are scattered with delicate buds. A '70s-style blouse mixes a lightly checked necktie with, yep, more flowers.

The collection will be carried in select stores, including at the Beverly Center, South Coast Plaza, Glendale Galleria, Brea Mall and Del Amo Fashion Center outposts. Blouses are $79.50 and dresses are $128 -- not cheap, but far less that the $7,895 that a 1969 Ossie Clark original is fetching on EBay.