It is often overlooked as a non-color, sacrificed for blues and reds and much hotter hues. But there is far more to white, as an English author explains so perfectly:

"White … is not a mere absence of color; it is a shining and affirmative thing, as fierce as red, as definite as black. …"

And when white is used in the arid garden, its presence can be profound, particularly in the West where it is the last hue to disappear at dusk. During those long dry evenings, these great white flowers are the toast of the garden.

Study any garden at sunset — and into the increasing darkness. The blues are the first to fade to black, then the reds. Golden yellow fades before pale lemon yellow, and only then do the creams and whites lose their luster. These pale petals, like night-vision goggles, reflect what little light is shed by the moon.

Sometimes they can appear luminescent in the moonlight, as with the yucca. This plant of the American West is pollinated by night-flying moths, and its white color is an adaptation to draw them "like a moth to a flame." Yucca has always been queen of the night garden, but there are other drought-resistant plants that are nearly as lovely day or night.

For sandy ground, the Matilija poppy, Romneya coulteri, is among the most spectacular dryland white flowers. Known as the fried-egg plant due to flowers that resemble the breakfast staple, it is an enormous perennial. This beauty grows in winter, then explodes into enormous plate-sized blossoms. The white is so pure that it seems bright even on a cloudy day, and appears to float like fireflies after the stalks disappear into the gloom.

Bougainvillea is famous for its intense red spectrum of flowerlike bracts. This frost-tender beauty is the celebrated queen of the heat belt of the U.S. Southwest and Mexico. Extensive breeding has resulted in a few snow-white bract hybrids, and some with the slightest pink blush, that are spectacular. They thrive in the heat and carry the night garden through the depths of summer. Bougainvilleas are among the few high-profile plants that take desert heat in stride. And they actually bloom best when very dry. The white hybrids may be too large for some gardens, but the new dwarf varieties make excellent low-mounding shrubs perfectly suited to small spaces and containers.

When the famous California plant breeder Luther Burbank set out to create the perfect white daisy, the result was a hybrid he named for snowcapped Mount Shasta. This vigorous and floriferous perennial was the result of crossing cold-hardy English oxeye with a large-flowered Japanese species; the near-perfect perennial blooms over a long season and produces exceptional cut flowers. Often sold as Leucanthemum maximum, the various named types in today's gardens differ in height and flower size. This is a perfect starter perennial for Western e gardens, where it proves to be tolerant of clay soils and neglect, as well as periods of drought.

When white flowers are securely placed in your garden, they'll rule the summer nights. This leaves you a rainbow of hues to flesh out the rest of your landscape. Where sunlight is intense, bring out the blues to soften glare. Where summer fogs bring gloom, pair them with reds and oranges to brighten the day.

Maureen Gilmer is a horticulturist. Her blog, the MoZone, offers ideas for cash-strapped families. Read the blog at www.MoPlants.com/blog.