Plants in the Eloise Butler Wildflower Garden

The Four Silphiums

by Gary Bebeau

As you can see from this table these plants are tall, with Prairie Dock being the tallest flowering plant in the Upland Garden. Here are the specifics on each plant.

Compass Plant: The flowers appear in several heads in long branched clusters. The common name comes from the tendency of lower leaves to be somewhat upright with the edges aligned in a north-south direction. As this plant inhabits the central United States, this fact allowed the early settlers crossing the prairies to use the plant as a sort of rough compass on cloudy days. The leaves are very deeply pinnately-divided which makes it entirely different from the others, and that is the source of the species name, laciniatum, which is from the Latin meaning “slashed” or “lacerated”.

Cup Plant: There can be several flower heads in a branched cluster. The stems are square in cross-section and smooth. Besides the height, the key feature is the opposite leaf pairs that surround the stem, appearing to be pierced by it, and forming a cup around the stem - hence the common name. The species name, perfoliatum, actually means "through the leaf," referring to the stem piercing the leaf. These cups easily collect water and are a source of liquid for birds. The plant has an extensive root system and does not transplant well except when very young.

Prairie Rosinweed (Prairie Dock): Growing from 4 to 10 feet high, this is the tallest of the four and the tallest flower in the Upland Garden. It has numerous flower heads on otherwise bare stems, the leaves being (most always) entirely basal - and quite large. They are hard to miss, with the triangular shape, heart shaped base, and large coarse teeth. The species name, terebinthinaceum, means "like turpentine." which may refer to the aroma of the resinous juice. Prairie Dock is the last of the four Silphiums to bloom, usually not until late August before any quantity of bloom is seen. The tall stems provide some vertical visual relief during the winter months.

Wholeleaf Rosinweed: This, the shortest of the four Silphiums, is the one you are most likely to encounter in a large clump. It is also the earliest of the four to bloom, usually showing open flowers in late July. There are usually a number of branched flower clusters at the top of the stem. The species name, integrifolium, is Latin for "entire-leaved" referring perhaps, to the many leaves that cover the stems. It can also refer to the leaf itself as being “entire”, that is, without teeth, but Rosinweed leaves have very tiny teeth. “Rosinweed” as a generic name has been used to refer to all Silphiums.

Native Status and Garden History: The Upland Garden was made a part of the Eloise Butler Wildflower Garden in 1944, thanks to the efforts of Martha Crone and Clinton Odell. When Martha Crone completed her 1951 inventory of all plants in the Garden, three of four Silphiums were present. Rosinweed was not on her list. Presumably it was added shortly thereafter. On the four, only two are native to Minnesota. Cup Plant and Compass Plant are native. Prairie Dock is a plant of the east central United States, not found further west than Iowa, Missouri and Arkansas. Rosinweed is reported to be native to parts of Minnesota in certain literature but the Minnesota DNR does not list the plant as native; however, it is native to much of the Central United States.

Medicinal Lore: Of the four, only Cup Plant, S. perfoliatum, has any reference in the literature as to early medicinal use of the plant. Densmore, Grieve and Hutchins all refer to the use of the root as a medicinal ingredient and give formulas and dosages. The root was used as a tonic, diaphoretic (stimulates perspiration) and diuretic. Densmore has, from her Chippewa research, perhaps the most information as she lists usage by the Chippewa for lung ailments, hemorrhage and joint pain.