Prenanthes racemosa (Glaucous White Lettuce)

Plant Info
Also known as: Purple Rattlesnake-root, Smooth Rattlesnake-root
Family:Asteraceae (Aster)
Life cycle:perennial
Habitat:sun; moist sandy soil; wet meadows, prairies, stream banks, fens
Bloom season:August - October
Plant height:1 to 5 feet
Wetland Indicator Status:none
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

Pick an image for a larger view. See the glossary for icon descriptions.

Detailed Information

Flower: Flower shape: 7+petals Flower shape: bell Cluster type: panicle Cluster type: raceme

[photo of flowers] Tightly packed clusters of short-stalked flowers at the top of the stem and arising from leaf axils in the upper plant. Flower heads are about ½ inch across with 9 to 16 pinkish to white rays (petals) that have a few small teeth at the tip. The styles are longer than the rays and have divided, curved tips; stamens are purplish and shorter than the styles. There are 2 layers of bracts. The outer bracts are very short and dark green or purple. The 7 to 14 inner bracts are usually deep purple, form a tube about ½ inch long, and densely covered in long, white hairs. Flowers are mostly erect to ascending, sometimes nodding. Flower stalks are densely hairy.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of lower leaves] Leaves are generally elliptic to spatula-shaped, usually broadest above the middle, hairless, toothless or with a few tiny teeth. Lower leaves are up to 10 inches long, to 3 inches wide, with long, winged stalks; leaves become smaller and shorter stalked as they ascend the stem.

[photo of stem leaves] Mid-stem leaves are mostly clasping, the upper leaves are mostly stalkless and reduced to bracts in the uppermost part of the stem.

[photo of upper stem hairs] Stems are erect, unbranched, green to dark purple or purple spotted, often with a white bloom (glaucous) like on the skin of a plum. Stems are mostly hairless except near the flower clusters, with a few sparse hairs just below the flowers and more densely hairy on the flowering stems and stalks.

Fruit: Fruit type: seed with plume

Fruit is a dry seed with a tuft of pale yellow hairs to carry them off in the wind.


Found primarily in wet meadows and other sunny, moist, grassy areas in late summer, this species is easy to distinguish from other Prenanthes species by the pinkish flowers with hairy, purplish bracts, mostly clasping stem leaves, and smooth stem below the flowers. P. racemosa is known by the synonym Nabalus racemosus in some references.

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More photos

Photos by K. Chayka taken in Anoka, McLeod and Otter Tail counties. Photos courtesy Peter M. Dziuk taken near Almelund, Chisago County, and at Schaefer Prairie Preserve, McLeod County.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Kenny h - East of rose creek on shooting star trail
on: 2017-08-08 11:10:59

I think I found the MOTHER of all Glacous White Lettuce...5 1/4 feet tall...1/2 inch diameter flowers yet but it won't be long...BEAUTIFUL SIGHT

Posted by: Steve Poole - Lost Valley Prairie SNA
on: 2020-09-02 20:25:08

There are now two verified locations of this at Lost Valley. Sometimes hard to find because of the other crap. Also they are now listed for Washington County.

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