That's what it is. The flowers are such a pretty color. Mine is blooming now too and I have two volunteers this year, the first ones I've had. I'm surprised I don't get more volunteers. Maybe the seeds just have a low germination rate - which might be good in the long run. Come to think of it, I tried to grow it from seed a couple times with no luck a few years ago. I got my plant from the native plant sale at the Nature Center.

I took a picture of a big patch of purple poppy mallow at Close Gardens this week. I'll post it when I get it on the computer. I wish I knew how close together they planted theirs. Just one plant by itself is kind of sprawly but their bed was a big mass and looked really nice.

I saw that bed last year too. I would guess about 12-14 inches for good cover. I am going to check Mobot's website about it.

Here is what they say about it. Looks like I might kill it if I try to move it....long tap root.
Quote:
General Culture:

Easily grown in dry to medium moisture, well-drained soils in full sun. Grows well from seed and may self-seed in the garden in optimum growing conditions. Long tap root gives plant good drought tolerance but makes transplanting of established plants difficult.

Noteworthy Characteristics:

Purple poppy mallow is a mat-forming, Missouri native perennial which most frequently occurs in dryish, rocky soils in prairies, fields and along roadsides scattered in several counties mostly northeast of the Missouri River. Plants typically form a low foliage mound from 6-9" tall on procumbent stems which spread along the ground to 3' wide. Solitary, upward facing, cup-shaped, five-petaled, poppy-like, magenta flowers (to 2.5" wide) continuously appear on thin stems above the foliage from mid-spring to fall. Stamens form a prominent central column typical of mallow family members, but with distinctive style branches. Leaves are palmately divided into 5-7 finger-like lobes. The closely-related Missouri native fringed poppy mallow (Callirhoe digitata - X910) is, by contrast, a spindly, erect plant which typically grows 2-3' tall.

Problems: Click for detailed list of pests and problems.

No serious insect or disease problems. Crown rot may occur in poorly drained soils.

Uses:

Good native ground cover. Border fronts, rock gardens, native plant gardens, wild gardens, naturalized areas or meadows. Sprawl over a stone wall. Fits well into both formal garden areas as well as wild/naturalized areas.End Quote.

When I bought my plant at the native plant sale, it was in a tube about 10 inches tall rather than a pot, I assume because of the tap root. I looked back at an old post. I bought it in '07 and it was callirhoe involucrata.
I don't know whether you can transplant them. Do you think your plant came up this year or last year?

I think the foliage looks a lot like a weed that grows in my yard and I've come close to spraying mine with Roundup. My perennial geraniums too. They all look very similar in the spring to me especially if I'm moving fast with the sprayer. : )

I'm curious about transplanting young plants too. It has such a long bloom time, I think a lot of people grow it in their flower gardens even if they're not native plant enthusiasts. You might get some replies if you ask in the Perennials Forum. It's also called Winecups by the way.

Mine spread more like 6 feet wide last year but not in a solid mat. I should try pinching it. It might behave differently now since it's more mature. I really haven't noticed how big it is this year.

I just found it is the larval host and nectar source plant for the little grey hairstreak butterfly. Also it must the be second year since that is when it blooms...I must just not have noticed it or it didn't get very big. I have that same weed and that's why I almost chopped it down.