Corydalis Drawing by Rene Eisenbart

BOTANICAL NAME: CORYDALIS SOUNDS LIKE: Or riddle this TYPE: Impossibly blue, spring-blooming perennial BASIC NEEDS: Bright shade to part sun, good drainage, even moisture, rich soil WORST ENEMY: Drying out; -0 degree F temperatures BEST ADVICE: Try several, keep the tags, see what works, and go back for more; best massed

Woodland perennial

Every great plant deserves a story, and Corydalis flexuosa, the blue-eyed box office hit of the decade, comes with a good one. Since I can't possibly improve on the way Graham Rice tells the tale in his book Hardy Perennials, I'll pass his telling along. The story opens in 1989 with three Englishmen -- James Compton, John d'Arcy, and Martin Rix -- on a plant expedition in western China.

"Frustration mounted as they were driven through dappled woods past startling sheets of blue, until the reluctance of their Chinese hosts to pause and allow the team to inspect the plants so inflamed their bladders that an urgent stop was insisted upon, during which time three small species of [Corydalis] rhizomes were secreted in a moss lined film canister.... A certain amount of subterfuge was necessary to ensure their introduction."

To say the least, the secret's out. In the past decade, those three stem snippets have been propagated into untold millions of plants under three cultivar names: 'Purple Leaf', 'Père David', and 'China Blue'. Each makes a low-growing, compulsively tidy groundcover with finely dissected foliage, topped by a cluster of upright, spurred blossoms that could turn turquoise to envy and rival the color of Paul Newman's eyes.

The differences among the three are subtle but worth noting, though all are choice woodland plants. 'Purple Leaf' has the best year-round foliage, with dark stains at the base of each leaflet. Though its flowers are somewhat less electric than those of the other two cultivars, it is unfazed by winter and is the earliest to bloom.

The rich, turquoise-tinged flowers of 'Père David' are the largest of the trio's (mind you, we're talking eighths of an inch), nodding above blue-green foliage on mahogany stems. 'China Blue' is the truest, brightest shade of a New England winter sky, and asks the same cultural conditions as the others: light shade, rich soil, and adequate moisture.

With the floodgates now open, nurseries are increasingly awash in this bleeding-heart relative (which means prices are coming down; I once paid twelve dollars for a four-inch pot!). Of late there's 'Blue Panda', awarded the highest azure prize of all for flowers that are Meconopsis (blue poppy) blue. I'm also high on the straight species, C. elata, with purple airbrushed flowers. If you're close enough to the ground, you'll find them sweetly fragrant; I've also found the plant singularly robust.

Bloom time for all these baby blues is anywhere between March and June, then perhaps October and, who knows, maybe into winter. Quite impressive, but I wouldn't say unstoppable, since a number will go dormant in summer and disappear without a trace. That's a little unnerving if you've a rotten memory, so consider leaving their tags in the ground. Film canisters will work, too.