Iris cristata

Iris cristata is the iris scaled down for the woodland floor, a dwarf native barely six inches high that spreads into low, overlapping fans of bright green blades. In mid to late spring the mats light up with small flowers, an inch and a half to two inches across, in soft lavender-blue to violet, each fall stamped with a white patch and a raised orange or yellow ridge. That ridge is the crest that gives the plant both the Latin name cristata, crested, and the common name crested iris, and the feature sets the species apart from the bearded and beardless irises alike.

The dwarf crested iris is a plant of the eastern woods, ranging from Maryland west to Oklahoma and south to Georgia and Mississippi, where the species threads through rich soil on shaded ravine slopes and wooded bluffs. Gardeners have carried the plant into cultivation for well over a century as one of the most obliging of native spring wildflowers, content to knit a shaded corner together where showier things sulk. The rhizomes creep along at or just below the surface, branching as they go, so a few starts widen season by season into a slow, well-behaved groundcover.

Small as the flowers are, they are built for company: the crest and pale signal patch act as a landing guide for the early bees that pollinate them, and the plant closes the spring flush before the woodland canopy fully leafs out. Like other irises the rhizome carries the family's mild toxicity and is better admired than sampled, which is part of why deer and rabbits tend to leave the fans alone. After bloom the foliage often goes quietly summer-dormant in dry shade, returning the following spring, so the crested iris asks for a season's patience and gives decades of return.

In the garden Iris cristata is a natural for the front of a shaded bed, the edge of a woodland path, a shaded rock garden, or the dappled ground beneath deciduous trees, wherever the soil is rich, humusy, and evenly moist but never soggy, since the plant resents wet feet. Massed as a groundcover the low fans and spring flowers make a fine carpet, and single clumps tuck neatly among ferns, foamflower, wild ginger, and other woodland companions. Give part to full shade, a top-dressing of leaf mold, and shelter from harsh afternoon sun, and let a colony broaden at a natural pace. Photo courtesy of Steven Faucette.