The kernel of a powerful idea resides within “Illumination,” an exhibition of abstract paintings by four women who worked in the deserts of the American Southwest and whose careers pretty much spanned the 20th century. But the kernel never really pops.

One reason is that the modest galleries of the Orange County Museum of Art, where “Illumination: The Paintings of Georgia O'Keeffe, Agnes Pelton, Agnes Martin and Florence Miller Pierce” is on view to Sept. 6, are over-crowded.