Flower:

Flat clusters (umbels) made up of 7 to 20 groups (umbellets) of 10 to 20 flowers each. Flowers are white, sometimes tinged pink, about 1/6 inch across with 5 petals, a creamy colored center and a pair of styles at the top.

The base of both the umbel and umbellets typically have no bracts, occasionally one. Umbellet stalks are 1 to 1½ inches long. Umbels are 2 to 3 inches across.

Leaves and stems:

Leaves are few and widely spaced, alternate, pinnately compound and variously covered in short hairs. The lowest leaves are up to 12 inches long, its leaflets oval to nearly round with large, coarse teeth. Leaves become progressively smaller as they ascend the stem, becoming deeply lobed in the upper plant.

At the base of the leaf is a sheath that wraps around the stem. In the upper stem a leaf may be absent leaving only the sheath. Stems are densely covered in very short hairs and have faint ribbing. Plants are few branched.

Fruit:

Fruit is a flattened oval pod with faint ribs, less than 1/8 inch long, and splits into 2 seeds.

Notes:

Just what we needed - a new non-native carrot species. Burnet Saxifrage is not on many people's radar at this time and is no doubt under-reported in the state due to its (superficial) similarities to other weedy white carrot species, most of which have more finely divided leaves. Its lower leaves and seedlings more closely resemble Wild Parsnip (Pastinaca sativa), which has yellow flowers and causes severe burns when affected skin is exposed to sunlight. We found Burnet Saxifrage growing alongside Queen Anne's Lace (Daucus carota), a much more widespread species with showy bracts, and we received a report from Beltrami County, where it was described as “invading our fields from a neighbor and is laying down a mat that nothing else grows through”. Wisconsin recognizes Burnet Saxifrage as a new invasive species, or at least a species to watch, and it is apparently under-reported there as well.

When we wrote the above paragraph in 2014, Burnet Saxifrage was a virtual unknown in Minnesota, with only 3 reported sightings. In 5 years it has raced across northern Minnesota from Polk and Marshall counties in the west to St. Louis in the east (see distribution map as of 2019 or the latest info on EDDMapS) and is still very likely under-reported here. In Wisconsin, we've seen it take over vast tracts of land with a dense monoculture and there is no reason to believe it will behave any differently in Minnesota. In 2015, Minnesota's Weed Advisory Group completed a risk assessment of this species and determined it was not a risk, though it should remain on the “watch list”. At the rate this group moves, it may be another 5 years before they decide it's a big enough problem for them to take further action but by then it will be like Tansy or Wild Parsnip—too widespread for effective control, let alone eradication.

It can be said that there are insufficient resources for Minnesota's agencies to tackle every known (potentially) invasive weed taking over the landscape and consequently they have to limit their focus. There is truth to that, but the fact remains that, while their attention is on Oriental Bittersweet or Grecian Foxglove (currently on the Eradicate list but with little hope of actual eradication), species like Burnet Saxifrage are allowed to run rampant, making the whole weed program not terribly effective. We don't have an answer to this, except to encourage people to contact your legislators or local agencies to make such weeds a higher priority. And volunteer to help eradicate known populations, an essentially thankless but necessary job.