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Plants of the Eloise Butler Wildflower Garden

Common
Name

Scientific
Name

Plant
Family

Garden
Location

Prime
Season
Purple Prairie Clover
Dalea purpurea Vent.
Pea (Fabaceae)
Upland
Early to Late Summer
Other names and notes
(Violet Prairie Clover) Slender, erect stems, small leaves pinnately compound with an odd number of small narrow leaflets (3 to 9, usually 5), leaves and stem mostly hairless; several stems may grow from the base. The plant is usually under 2 feet tall (range 8 to 35") and similar in appearance to the slightly taller White Prairie Clover, D. candida. The flower is an inflorescence from the bottom upward on a dense spike with small 1/4" purple 5-part flowers with bright orange stamens that protrude. With a taproot that can extend to 6-1/2 feet deep, it is drought tolerant and as a member of the pea family, it fixes nitrogen in the soil and benefits from a prairie burn allowing soil locked seeds to germinate after which it will grow more profusely. Some books list the genus as Petalostemum, however, USDA has adopted the newer classification to the genus Dalea, named for Samuel Dale, (1659-1739), an English botanist and botanical collector and author of several botanical books. The species name purpurea is Greek for "purple". Specimens were originally collected by Lewis and Clark. Details below.
Purple Prairie Clover
Purple Prairie Clover
Above: Blooms of mid-July, the same time as the White Prairie Clover
Below left: Near the end of the bloom period as the flowers progress from bottom to top. Below Right: The narrow leaflets of the pinnately compound leaf.
Purple Prairie Clover
Purple Prairie Clover leaf
 
 

Notes: This plant was first introduced to the Garden by Eloise Butler on July 12, 1910 with plants she obtained from the grounds of the Agricultural College in St. Paul. The plant is included on Martha Crone's 1951 census of plants in the Garden. It is native to Minnesota to all but a handful of counties - those exceptions being mostly in the NE Quadrant of the state. It has wide native distribution in the United States ranging from the Basin and Range area of the west to the Appalachians in the east. It is most abundant in the uplands of the true prairie. However a number of the eastern states report special concern for the plant such as Kentucky, "endangered" in Tennessee and considered "extirpated" (eradicated) in Michigan and Ohio.

Lore and use: This is a highly nutritious plant for livestock forage. It is a warm-season legume that is nitrogen fixing. Overgrazing is detrimental to it, but a burn will stimulate germination of seeds in the soil and the plant will grow more profusely. Human use is restricted to medicinal uses. It has been reported that a tea made from the taproot will reduce fever in measles victims. Meriwether Lewis reported that bruised leaves were steeped in water and applied to fresh wounds. Densmore reports its use among the Minnesota Chippewa for heart conditions. A decoction was made from a handful of leaves and flowers in 1-1/2 pints of water. Their dosage was 1/2 cup, repeated in a half hour if necessary.

Lewis and Clark: Meriwether Lewis collected specimens of this plant on three known occasions. The first was on July 20, 1804 near present day Nebraska City, Nebraska. This specimen was lost on its way back to President Jefferson. His other two specimens survive and are in the Lewis & Clark Herbarium in Philadelphia. One of these is believed to have been collected in 1804 also. The other one was collected on July 22, 1806 in Montana and was labeled by botanist Frederick Pursh. (Thanks to Kathy Lloyd, Montana Native Plant Society for this information on Lewis and Clark.)

  
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References: Plant characteristics are generally from sources 15, 16, 30, 31, 33, W2 & W3. Distribution principally from W2 and also 31, 34 and W1. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.  
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