How a swamp flower became a lovely iris

Carl Wyatt lives in the Ozark Mountains of Missouri, near the little town of Marquand, where he farms for a living and breeds new plant varieties on the side. But what began as an avocation is making ever-increasing demands on his time.

What has particularly grabbed the attention of horticulturists recently is Mr. Wyatt's nearly two decades of work with several varieties of native American iris. Thanks to his efforts, a pretty wildflower that thrives in swamps has evolved into a ''garden beauty,'' to quote George Park, the South Carolina seeds-man.

The practical approach that is instinctive with every farmer runs over into Wyatt's plant breeding. He contends that every plant breeder ''should make 'growa-bility' the first requirement in a new plant.'' And that ability for the plant to grow relatively easily over much of North America is what this Missouri farmer has bred into the new domesticated variety of American iris.

The new iris grows readily from Zone 4 through 9 on the hardiness map. Put another way, it will bloom readily from Louisiana all the way north into Maine and in several of the milder regions of Canada as well.

Wyatt's 17 years with three species - Iris fulva, Iris foliosa, and Iris giganticaeruleam - have resulted in a plant that produces well-formed blooms in a wide range of colors that are as bright in the North as in the South. In the process he converted a plant with a preference for swamplike growing conditions to one that enjoys the dry, by comparison, soil conditions of a garden.

Previous faults with some of the domestic species - rampant foliage and elongated rhizomes - have been eliminated, and resistance to fire-scorch disease has been introduced.

Reds, yellows, blues, lavenders - virtually every color in the rainbow - are available in the new iris. Park maintains that the colors are consistently brighter even than the hitherto renowned Japanese iris. The color range includes the first true red among iris species.

American iris establishes itself rapidly, forming clumps with 4- to 5-inch flowers on 4-foot-long stems.

American iris blooms about mid-April in Louisiana's Lake Charles region and a week later for every 100 miles north of that city.

Just how cold-tolerant the American iris is was shown to Wyatt when he found them growing up through ice in a Missouri pond, quite unharmed by a late cold spell. On the other extreme, the plant's hardiness was emphasized when fire swept through a greenhouse full of seedlings in 1980. The blaze scorched the roots of the 9-inch plants, which were taken outside and watered. Eight days later color began returning to the leaves in 70 percent of the plants.

Because they have descended from swamp plants, American iris do best where it is consistently moist. Dig in as much organic waste as you can spare and feed with a balanced fertilizer once the plants have become established.

Mulch the bed well, both to retain moisture and to keep down weeds. In winter the mulch will prevent the soil from heaving and snapping the roots. In dry spells, give the iris as much water as you would your lawn - one inch of water a week in medium to heavy soil; more than that for sandy soil.

For more information on the new American iris write to George W. Park Seed Company, Greenwood, S.C. 29647.