Crested Dwarf Iris

I have always had a fondness for the wildflowers of spring woodlands and have planted them in shady spots as a harbinger of my favorite season. One of the hardiest of the spring ephemerals is Crested Dwarf Iris, Iris cristata.  I have purchased many of these (and other native wildflowers) over the years from the NC Botanical Garden (http://ncbg.unc.edu/) in Chapel Hill. They run an honor system plant sale from April through October and usually have a large sale event in September. I have also transplanted some from areas that were being developed by digging a few of the stubby rhizomes and planting them in shallow soil. It seems these tiny plants do best on rich wooded slopes, ravines, stream banks and other places where their rhizomes remain partially exposed and the beautiful sword-shaped leaves are not covered by deep leaf litter.  If you have typical garden varieties of iris you may do a double take when you first see this one – a tiny plant reaching only 3-5 inches in height. The flowers are usually some shade of blue or violet (occasionally white) and they tend to grow in patches, offering a visual delight to the spring woods walker.

Crested Dwarf Iris flower (click to enlarge)

They are named for the yellow crinkled crest on the sepals, which serves to guide pollinators (mainly bees) to the nectar deep within the throat of the flower (although I have also read it may give the bee something to grasp onto while navigating toward the nectar). If you look closely at an iris, you will notice it has an unusual flower structure. The three largest petal-like structures are actually sepals (which enclose and protect the flower bud before it opens). In iris flowers, they are also called the falls. The wide tip of the fall provides a place for pollinators to land.

Crested Dwarf Iris style arm (click to enlarge)

Arching over each fall is a modified reproductive part called the style arm. This is probably the most unusual part of an iris flower. I had read about this but decided to take a closer look which required lying down and propping the flower parts open with a tiny twig to better view and photograph them (the things you have to do for science).

Dwarf Crested Iris flower parts

Just under the tip of the style arm is the stigma lip. This is the area that receives the pollen. It is a light-colored exposed curved edge just under the arch. A visiting bee must push under this style arm in order to access the nectar that is deep inside the throat of the flower. While crawling down toward the nectar glands, pollen is scraped off the back of the bee by this edge and attaches to the sticky stigmatic lip. The anthers (male, pollen-producing parts) are elongate structures behind the stigma lip. After the bee gets scraped of pollen, it then brushes up against the anther and gets fresh pollen. That pollen is unlikely to be transferred to this particular stigma lip as the bee backs out (they often exit through the gap in the arch). Bees are the primary pollinators as few other insects have the strength to push under the style arm.

Crested Dwarf Iris rhizomes (click to enlarge)

The rest of the plant parts are a bit more the usual…the true petals (often called standards in iris) are the smaller of the colorful parts, and most often stand in a more upright position than the falls. Like in most flowers, they serve to attract pollinators. The rhizomes are short and chunky and connected to one another by slender runners. The sword-like leaves are attractive even when no flowers are present.

Crested Dwarf Iris flower bud

One thing I noticed yesterday is how quickly the flower opens. Here is a picture of the flower bud on one iris at 10:37 a.m. yesterday. When I returned from some errands at 3:00 p.m., the flower was fully opened.

The modern name for the iris flower is believed to have originated in ancient Greece. There, the flower was associated with the goddess Iris, a divine messenger who traveled from heaven to earth on rainbows. Throughout history, iris have represented wisdom, faith, and courage and been used as a royal symbol of king and queens. While that glory most probably went to their larger cousins, the diminutive Crested Dwarf Iris also deserves recognition and appreciation as we wander the spring woods.