Polygala verticillata (Whorled Milkwort)
|Also known as:|
|Habitat:||part shade, sun; fields, prairies, open woods|
|Bloom season:||July - October|
|Plant height:||4 to 12 inches|
|Wetland Indicator Status:||GP: FACU MW: UPL NCNE: UPL|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Spike-like raceme, usually densely arranged, up to 2 inches (5 cm) long at the top of the plant and the tips of branching stems. Flowers are white to greenish-white to pinkish, flanked by a pair of spreading, oval to egg-shaped, petal-like sepals, each less than ¼ inch (4 to 5 mm) long, rounded to blunt at the tip and have a conspicuous midvein. Three small petals are fused into a short column in the center, with a fringed, yellowish crest. Flowers bloom from the bottom of the spike up.
Leaves and stem:
Leaves are whorled, usually in 4s or 5s, up to about 1¼ inches (3 cm) long, to ¼ inch (5.5 mm) wide, linear to narrowly lance-elliptic, mostly widest near the middle, toothless, hairless, pointed at the tip, tapering at the base, stalkless or sometimes short-stalked. The lowest leaves may be significantly reduced in size, the largest leaves are usually around mid-stem. Stems are erect, branched, single from the base and hairless.
Fruit is an elliptic to nearly round, slightly flattened, 2-seeded capsule. Seeds are 1.2 to 2.2 mm long, hairy, with a 2-lobed appendage that is 1/3 to half as long as the seed. Sepals and capsules both drop off at maturity leaving a nub on the stem where the flower stalk was attached.
Whorled Milkwort is present in about a third of Minnesota, found in open grasslands and woodland openings. The flower spike is similar to the related Seneca Snakeroot (P. senega) but the latter has alternate leaves and is typically unbranched. It is also very similar to White Milkwort (Polygala alba), which is not present in MN but is just to our west and south on the Great Plains, has more pure white flowers with green centers in clusters up to 3 inches long, mostly alternate leaves, only the lowest 1 or 2 nodes with whorled leaves. There are multiple varieties of P. verticillata, but these are not universally accepted; they are apparently distinguished by the length of the flower stalk and whether leaves are whorled all the way up the stem (excluding the flower clusters). P. vercillata var. isocycla, with nearly stalkless flowers (stalks .3mm or less) with whorls all along the stem is considered the var present in Minnesota.
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Photos by Peter M. Dziuk taken in Otter Tail County.
Have you seen this plant in Minnesota, or have any other comments about it?