The Minnesota Department of Natural Resources produces a list of rare plants and assigns these to three levels of concern: Endangered - if threatened with extinction; Threatened - if likely to become endangered; and Special Concern - extremely uncommon, requiring careful monitoring of status.
Listed below are some of these plants which grow at Eloise Butler Wildflower Garden and Bird Sanctuary. Within a small space of 15 acres can be readily viewed, in the appropriate season, a group of plants that would require hours of searching out in the wild, if you could locate them. Some of these have been in the Garden since its origin. Some were planted as representative species of native Minnesota plants. As there are restrictions and laws against collecting these in the wild, we are fortunate today, that a number of native plant growers offer these plants to the public where they can be perpetuated in private and public gardens. We list with the plant a brief description, the flowering season and which level of concern the plant is listed as.
Endangered: Butternut, Christmas Fern, Dwarf Trout Lily, Eastern Hemlock, Goldenseal, Shooting Star, Wild Quinine.
Threatened: Glade Mallow, Great Indian Plantain, Thin-leaved Coneflower, Witch Hazel.
Special Concern: Goldie's Fern, Kentucky Coffeetree, Nodding Wild Onion, Rattlesnake Master, Short's Aster, Silvery False Spleenwort, Smooth Rockcress, Snow Trillium, Swamp White Oak, Twinleaf, Whorled Loosestrife, Wild White Indigo.
Links in the text take you to more information. View DNR List - PDF
Butternut Juglans cinerea L. [MN Endangered List.]
Butternut was first planted in the Garden by Eloise Butler in 1909. It is a native, erect, small to medium size tree, growing 40 to 70 feet, with a broad open crown. Male and female flowers are separate on the same tree and appear with the new leaves in Spring. Flowers mature to a cluster of 3 to 5 oblong, sticky, nuts with a yellow-green husk which contains an irregularly shaped 2-celled nut that has edible, oily meat. Trees need 12 to 20 years to produce any quantity of nuts. Butternut wood is much lighter than Black Walnut, but works easily with tools. It has been used in furniture and interior decoration but because of the scarcity of harvest-able trees it does not have much current use. Around the early 1900s it was much in use in Minnesota for interior trim in finer houses. Because large trees rarely reach 75 years of age, large pieces of lumber are not found even in specialty lumber yards. In former time periods when they were more abundant the nuts were used in baking, much like walnuts are today. The fruit husks will make a yellow and orange dye. The oldest Butternut in the Garden was felled by a storm on June 23, 2003. [Back to top plant list]
Christmas Fern Polystichum acrostichoides (Michx.) Schott. [MN Endangered List]
Eloise Butler first planted Christmas Fern in 1908. She wrote in 1914: "The Christmas fern, so common farther east takes kindly to the bog as well as to the rich black soil of the wooded slopes. It is sometimes mistaken for a short leaved variety of the cultivated Boston fern, but a comparison of the fruit dots on the backs of fronds will show the difference." It is an evergreen fern growing in circular arching clumps. Fronds are either sterile or fertile. Fertile fronds have both sterile and fertile pinnae. The upper pinnae are fertile and are much smaller then the sterile pinnae lower on the frond. Christmas Fern is a good fern for beginners in fern culture. The common name comes from the use of this evergreen fern for decoration during the Christmas time. [Back to top plant list]
Minnesota Dwarf Troutlily Erythronium propullans A. Gray [MN Endangered List]
Minnesota Dwarf Troutlily was introduced by Eloise Butler in 1909. It is a perennial ephemeral of the early spring woods and the least seen of the three Minnesota species of trout lily. It was first identified in 1871 when Faribault teacher Mary Hodges sent a collected example to Professor Asa Gray at Harvard. He determined it was a previously un-recorded species and gave it the botanical name it has and presented a specimen of the plant to the Kew Herbarium in London the same year. It is easily mistaken for the White Troutlily. E. albidum, when not in flower. The flower is much smaller and usually has 5 tepals not the 6 of E. albidum. Some of those in the Garden were recently relocated to allow for replacement of the bridges. A key issue for the future of this plant is habitat protection as the plant does not set seed unless it crosses with the White Troutlily. It only perpetuates itself by vegetative propagation via a root stolon. [Back to top plant list]
Eastern Hemlock Tsuga canadensis (L.) Carrière [MN Endangered List]
Hemlocks first arrived in the Garden in 1911. They require cool moist acidic soil and shade to develop when young. After that they can become a dominant species. They have a straight trunk, a conical crown of long slender horizontal, somewhat drooping, branches, and growing 60 to 70 feet high. Minnesota is at the extreme western and southern edge of the tree's range. The MN DNR states there are only about 50 mature trees remaining in the wild. In 2013 the tree, which was listed as of "Special Concern", was moved to "Endangered". The old population in the Garden and the younger population at the MN Landscape Arboretum is therefore of special importance. The stand in the Garden contains the largest known Eastern Hemlock in Minneapolis which is now on the Minneapolis Heritage Tree List. The wood of Eastern Hemlock is brittle and full of knots, thus not valuable for anything but rough wood needs. An extract of Hemlock bark was once a commercial source of tannin for the production of leather and that use led to the destruction of many mature stands of the tree. Other than the bark, the remainder was discarded. Tea was said to be made from the leafy twigs. [Back to top plant list]
Goldenseal Hydrastis canadensis L. [MN endangered list]
Goldenseal has a long history in folk medicine. The root has been sought throughout its range in the eastern United States to such an extent that is now endangered in most areas. In Minnesota it was never found outside of the counties of the SE Corner of the state and wild populations are now only known in five counties. Each plant produces only a single flower in the spring which matures into a cluster of red berries resembling raspberries. The foliage is a striking dark green. It was first planted in the Garden in 1910 by Eloise Butler. Both Martha Crone and Cary George planted it. It blooms in late Spring. [Back to top plant list]
Shooting Star Dodecatheon meadia L. [MN Endangered List]
Shooting Star is a short (8 to 18") native perennial that has a rosette of basal leaves only, from which arise one or more flower stalks which then develop a somewhat whorled umbel of flowers that can have white, lilac or pink petals. As they mature the flower nods and the corolla lobes turn backward and upward from the flower, giving the flower it's name. These upward turned petals expose the inside of the corolla tube with maroon and yellow colors and a ring of yellow stamens. This is one of the earliest upland plants to bloom, usually in late Spring. The entire plant dies back by mid-summer. They have been in the Garden since Eloise Butler introduced them in 1910. Today, native populations are known only in Mower County. There is a more widespread species, D. amethystinum, known as Dark-throat Shooting Star where the corolla is a deep rose-purple. Research by the University of Minnesota throws suspicion on whether the two species are really that distinct however. [Back to top plant list]
Wild Quinine Parthenium integrifolium L. [MN Endangered List]
Wild Quinine, also known as American Feverfew, is a native erect long-lived perennial forb growing from 1 to 4 feet in height on a stout stem rising from a basal rosette of leaves which are on long stalks and can be up to 12 inches long. The stem leaves are shorter, lance-shaped and become stalkless near the top. At flowering time in early summer, dense flat-topped clusters form at the top of plant. These are composed of 1/3" wide flowers which have a tightly packed center disc of 15 to 35 infertile white florets. Around the outside are placed 5 very small white fertile ray florets which make this flower quite distinctive. The heads have a light medicinal fragrance and can be used as cut flowers. It needs full sun with mesic to dry conditions. The root rhizomes will vegetatively spread the plant. There are no known pest problems and a group of these plants will have an extended summer flowering season. The plant does not have a long history in the Garden as it is not indigenous. It was not listed on Martha Crone's 1951 census but was on the 1986 census. It was replanted as recently as 1998. Its native habitat in Minnesota was always restricted to the SE corner. The Minnesota DNR reports that very little of the original range is left as agriculture has converted most of the original habitat to cropland. The DNR has acquired two abandoned railroad rights of way where the species was growing and designated those strips as a Scientific and Natural Area. Native Americans of the SE Unites States are known to have used the plant for medicinal purposes, particularly for treating burns. [Back to top plant list]
Glade Mallow Napaea dioica L. [MN Threatened List]
Glade Mallow is a native erect perennial early summer flowering forb growing on stout stems to 6 feet high, with occasional branching in the upper section. It is a very old species and is the only dioecious species (Male and female flowers are on separate plants) of the Malvaceae family found in the western hemisphere. It is the only species of Napaea found in Minnesota or Wisconsin. The flower clusters are quite dense. The five white petals are offset in color by a large yellow pistil in the center of the female flowers. It may grow in full sun to partial shade in woodland openings or in full shade under the tree canopy. Plants in full shade will not be robust. In all cases the plant requires moist soil. In the wild it is usually found along stream edges. [Back to top plant list]
Great Indian Plantain Arnoglossum reniforme (Hook.) H. Rob [MN Threatened List]
This is a big bold plant with 3 to 9 foot stems that have 6 to 8 angles, are grooved and have a purplish tint. The basal leaves are large, palmately lobed and somewhat kidney shaped as the species name indicates. The inflorescence consists of dense clusters of small white flowers, which, while being an Aster family plant, have only disc florets, no rays. It blooms in early summer and is found in open woods, roadsides, prairies, where there is full to at least partial sun. In the wild in Minnesota, this species is only found in the SE corner of the state. This is too large a plant for the typical home native plant landscape unless you have a large area where this could be a background specimen. [Back to top plant list]
Thin-leaved Coneflower Rudbeckia triloba L. [MN Threatened List]
Thin-leaved Coneflower is a native biennial or short-lived perennial, growing to 5 feet high on branching stems. There are 3 varieties and the one native to Minnesota is var. triloba. This refers to the 3-lobed lower stem leaves. The flower head is 1 to 1.75" wide with a dome shaped purplish-brown central disc. It grows best in fertile soils in full sun with wet to moderate moisture conditions. It re-produces by seed only. It is not indigenous to the Garden, but was introduced by Eloise Butler in 1923 with plants from Lake Geneva Wisconsin. Martha Crone planted it a number of times and then Susan Wilkins has added plants in the Upland Garden in recent years. The plant has various other common names such as 'three leaved coneflower', which is a poor name as the leaves are lobed, not separated into leaflets; 'brown-eyed susan' has also been used fairly often but that is confusing with 'Brown-eyed Susan' and 'Orange Coneflower' which also have brown discs. Southeast Minnesota is the NW limit of this plants range in North America.[Back to top plant list]
Witch Hazel Hamamelis virginiana L. [MN Threatened List]
The Witch Hazel is a unique shrub as Martha Crone explains: "The lingering flowers are one by one finishing their bloom. Yet there is one wild flower that will remain even until bleak November. It is the Witch Hazel, which waited late to bloom but now the woods brighten with the yellow fringy petals. After the large leaves have turned brilliant colors and long since fallen, almost overnight, the mass of yellow flowers appears." Those flowers are usually in groups of 3 and the 4 yellow petals resemble twisted straps. In mild years some leaves may yet remain at flowering time. This is an understory shrub, reaching 12 to 20 feet in height with several twisting branching trunks. While pollination occurs in the autumn, the pale brown woody fruit matures only the following autumn after fertilization in the spring. The 2-beaked seed capsule then splits and violently discharges two shiny black seeds, hence one of the common names - Snapping Hazelnut. There is a long medicinal history for the plant, from folk use for treating swellings and tumors to being listed in the U.S. Pharmacopoeia (the USP). Eloise Butler introduced the species to the Garden in 1910 and there is a very old specimen in the Woodland Garden. In the wild today in Minnesota it is only known in 4 counties. New plants have been added to the Garden in recent years. [Back to top plant list]
Goldie's Fern Dryopteris goldiana (Hook. ex Goldie) A.Gray [MN Special Concern List]
Goldie's Fern is named for its discover, John Goldie, Scottish botanist (1793-1886) who collected the plant on a trip to North America, returning to Scotland with samples in 1819. It has been in the Garden since at least 1936 and was replanted in 2006. Goldie's Fern is a large conspicuous fern of moist forests and slopes; it is one of the largest of the wood ferns with upright arching oval to triangular pinnate-pinnatifid fronds growing 3 to 4 feet tall. Offshoots from the rhizome can form dense colonies over time. The plant is long-lived and a clump can be difficult to move. Fronds are bright green with a paler green edge when young, giving a two-tone effect. The blades abruptly taper to the tip and bear 12+/- pairs of pinnae. It is only known from 12 counties in the state. [Back to top plant list]
Kentucky Coffeetree Gymnocladus dioicus (L.) K. Koch [MN Special Concern List]
Kentucky Coffeetree is a superior tree for the home landscape as it is not known to be susceptible to disease or insects in this area. Male and female flowers are on different trees so it you want fruit both must be nearby. The flowers are in a long terminal raceme and quite pretty with a purple calyx and white petals. The compound leaf is the largest of any North American tree species. The tree leafs out late and appears dead as the leaf buds do not swell before leaf-out. Flowers occur after the leaves are out. Fertile flowers produce a thick dark red-brown pod containing 4 to 6 beans; the pod usually stays on the tree over winter. The early settlers used the beans as an attempted substitute for coffee but soon abandoned that when West Indies coffee became available. Trees have been in the Garden since Eloise Butler planted the first ones in 1909. Martha Crone planted 36 in 1934 and those remaining are now quite large. [Back to top plant list]
Nodding Wild Onion Allium cernuum Roth. [MN Special Concern List]
Nodding Wild Onion is one of is one of seven Allium species known to Minnesota but the only native considered at risk. It was formerly more widespread, including the metro area, but is now found in the wild in only four counties in the SE corner of the state and was not even known to still be extant in the state until these populations were found in 1981. It was first introduced to the Garden by Eloise Butler in 1910. The leaves are all basal, forming a rosette. The flowering stem is erect - up to 1-1/2 feet high - with an umbel of numerous pretty nodding flowers that open in mid to late summer. Eloise wrote ". . . pink balls of fairy grace lifted on slender, leafless stalks give a magical brilliancy to the billowing grasses of large expanses of the prairie. Do not be disconcerted by the name. The onion is, after all, a sort of lily, considered by every one a flower queen, and the odor is not perceptible, except when the plant is bruised. The leaves of this Allium are very narrow, unlike those of the early leek, so abundant in the wood in early spring." It prefers partial shade in cooler areas and accepts a variety of soils and the root system can produce offsets to form clumps. It should be in any native garden. [Back to top plant list]
Rattlesnake Master Eryngium yuccifolium Michx. [MN Special Concern List]
Rattlesnake-master is an erect native perennial reaching to 5 feet high on stiff, green smooth stems. A characteristic of the yucca-like leaf is the parallel vein structure. The leaf clasps or wraps around the stem with a long sheath. At the top of the plant in late summer form long-stalked round one inch clusters of tiny flowers which have white corollas and brown anthers on the stamens for contrast. There is a honey-like scent. From a distance the clusters look like round pincushions. It is an easy plant to grow but it needs its proper spot. The species name refers to the Yucca-like leaf. There is no other plant in our area to confuse with this one. Martha Crone reported planting it, as did Cary George and most recently Susan Wilkins. In the wild it is only known today from counties in the SE section of the State.
A word should be said about Andre Michaux whose name ('Michx.') is listed several times on this page as the author of the published plant classification. He was a French botanist (1746-1802) who made many exploring expeditions in the U.S. collecting and cataloging many species. Two important works of his are the Histoire des chênes de l'Amérique septentrionale (1801 - Oaks of North America), and the Flora Boreali-Americana (2 vols., 1803). His son Francois, traveled with him and the father’s notes were later used for the 3-volume North American Sylva, for which Thomas Nuttall provided some supplements.
[Back to top plant list]
Short's Aster Symphyotrichum shortii Lindl. [MN Special Concern List]
Short's Aster was originally introduced to the Garden by Eloise Butler on Aug. 28, 1926 with plants from Waseca MN, with more plants on Sept. 4th. It was planted most recently in 2012. Asters are confusing and this one has a resemblance to the Sky-blue Aster, S. oolentangiense, in that the ray flowers are a light blue in a flower head about 1 to 1-1/2 inches wide. The difference is in the leaves where all the leaves of Short's have heart-shaped bases, whereas those of the Sky-blue have such bases only on the very lower leaves. In the wild it is found only in several counties of SE Minnesota and as late as 1986 it had been posted to the Threatened Species List but as of 2013 it has now dropped down to the Special Concern List. It is a late season bloomer - September and October - that grows in partial sun to shade, but somewhat drier soils - similar to the Big-leaf Aster, Eurybia macrophylla. A word about that genus name: All the new world asters, formerly in the genus Aster, have now been reclassified, most into the genus Symphyotrichum. [Back to top plant list]
Silvery False Spleenwort Deparia acrostichoides (Sw.) M. Kato [MN Special Concern List]
Eloise Butler first planted it in 1909, then again in 1911 and 1918. All the plants came from East Coast sources. Martha Crone planted them also, most notably 50 in 1956 when she developed the Fern Glen. Within Minnesota it has only been found in the wild in 5 counties of the SE corner - Fillmore, Houston, Olmsted, Wabasha and Winona. It is the only species of Deparia in the central and NE North America. It is a tall soft green color fern forming a leafy clump as much as 30 inches high. The sori are long and mostly straight arranged in a herringbone pattern on the underside of the pinnules. They are covered with an indusia which attaches to the vein side of the pinnule. It is silvery at first, hence the common name. Spleenworts are so-named in reference to their supposed medicinal properties for spleen problems. However this fern is not a spleenwort. At one time it got stuck in the Asplenium genus (the true spleenworts) and thus picked up the name "false spleenwort". They require rich, neutral to acidic moist soil in the shade. [Back to top plant list]
Smooth Rockcress Boechera laevigata (Muhl. ex Willd.) Al-Shehbaz [MN Special Concern List]
Smooth Rockcress is a native biennial, producing a basal rosette of leaves the first year and then in the second year raising a 3 to 3-1/2 foot tall stem which has long lanceolate shaped leaves which clasp the stem. At the top develops a tall raceme of 16 to 45 drooping stalked flowers which become erect as they open. They are small (1/6 inch wide) 4-part, white petals and 4 light green sepals, not the most outstanding flower ever seen and in fact the entire plant, despite its height is easy to miss in the late spring woodland when and where it blooms. The species is in the Mustard Family and like most such plants flowers are forming in bud stage at the top, with flowers open below them and under that seed pods are forming from the earliest blooms. Seeds form in a long thin pod, more rounded than flat in cross section, and it spreads outward and then curves downward. However, unlike many Mustard Family plants this one is not considered as invasive. The wild population in Minnesota is now known in only 7 counties - 5 in the SE corner and Dodge and Hennepin. [Back to top plant list]
Snow Trillium Trillium nivale Riddell [MN Special Concern List]
As the name implies this is one of the earliest blooming flowers in the Garden, sometimes prior to full snow melt. Like all Trilliums the stem is an above ground portion (a flowering scape) of the underground rhizome. It rises rarely more than 4" high. And like all true Trilliums the 3 leaf-like parts are actually bracts just below the flower base. They are of course much larger than the normal bract that you see, but they are equipped to fulfill the function of a leaf. The flowers are only one inch wide with 3 white petals with the 3 much narrower blue-green to purplish sepals placed between them. The underground rhizome will form a nice clump if left undisturbed. By late spring the plants have died back and gone dormant. Eloise Butler introduced the plant to the Garden in 1910. Martha Crone rescued 325 plants from a construction site in Mankato in 1939. March 26, 1987 is earliest noted bloom date at the Garden. Minnesota is on the western edge of its range. Martha Crone wrote: "After a long northern winter, what a welcome sight to find the brave little Snow Trilliums pushing thru the heavy blanket of leaves. They seem to defy the chilly nights and frosty weather." [Back to top plant list]
Swamp White Oak Quercus bicolor Willd. [MN Special Concern List]
Swamp White Oak is a native deciduous tree growing to almost 100 feet tall, usually with an irregularly shaped crown due to confining conditions but in the open it can have a very nice rounded vase shape. Like all oaks the male and female flowers are separate on the tree, the males in hanging catkins and the female being small stubs growing in the axils of newly formed leaves on new twigs. The acorns have a distinguishing long stalk. The leaves are not as deeply lobed as others of the White Oak group - but variable in shape anyway, like most oaks. They do however, have a very pale underside, from which comes the species name of bicolor. It is said to prefer moist acidic soil but trials at the Minnesota Landscape Arboretum have determined that it grows better if the site is well drained. The fall leaf color is an uninteresting rusty brown. The species is indigenous to the Garden but at some point those died out. They were re-introduced some years ago but are still of small size. In the wild the tree is still found in a handful of counties, principally from the metro southeast. [Back to top plant list]
Twinleaf Jeffersonia diphylla (L.) Pers. [MN Special Concern List]
Twinleaf is a native spring flowering perennial forb growing from 4 to 10" high on smooth reddish stems. The leaves are basal on long stalks and are divided lengthwise into two distinct, but very slightly unequal, kidney shaped leaflets (hence "Twinleaf"). The flowers are solitary, occurring on a leafless scape. There are usually 8 elliptic to obovate white petals. Paired with the petals are 8 stamens with yellow anthers surrounding a green ovary. The fruit is most interesting, being a fairly large capsule that when mature, splits along a horizontal line near the top to form a lid which then opens as the capsule bends downward to release the seeds. It needs the rich loamy soil of woodlands with moderate moisture and dappled spring sunlight. The genus, Jeffersonia, is named for the 3rd President of the U.S., Thomas Jefferson. This was an honorary designation due to his great interest in Botany. The plant does not have a long history in the Garden - the first plants were added by Martha Crone in April 1957 when she planted 3 south of the Garden office in what may the same spot they grow today. Plants were received from a Mr. Johnson at the University of Minnesota. In the wild in Minnesota, its native habitat has been reduced to farmland and it is now only found in secluded valleys in the SE corner of the State. [Back to top plant list]
Whorled Loosestrife Lysimachia quadrifolia L. [MN Special Concern List]
Whorled Loosestrife was introduced to the Garden by Eloise Butler in 1913. The native population of Minnesota was once reduced to a few spots in Pine County but now 13 additional populations have been found - all in Pine County - so the designation has been lowered to "special concern". The plants grow 2 to 3 feet high with leaves in widely spaced whorls of 4 or 5 on the hairy stem. The small flowers then rise on long stalks from the leaf axils forming a whorl also. The yellow of the petals is contrasted by reddish streaks in the petals and petal edges and a conspicuous red fleshy nectary band at the base of the corolla, from which rises a united group of stamens. You can see many of these plants in the Upland Garden in Early to Late Summer. The two Greek words from which is derived the genus name are - lysis meaning "a release from" and mache is for "strife". This supports the common name of "Loosestrife" which is said to refer to a supposed power to soothe animals or "loose" them of their "strife". This perception led people to tie a branch to the yolk of oxen, making them easier to handle. The plant is known to repel gnats and other irritating insects which maybe explains why the animals were easier to handle. Pliny the Elder wrote that the odor of loosestrife would keep snakes away. [Back to top plant list]
Wild White Indigo Baptisia alba (L.) Vent. var. macrophylla [MN Special Concern List]
It is also known as White False Indigo and there are some scientific name differences found in references to this plant. The Minnesota DNR, as of 2019, still list the plant as Baptisia lactea (Raf.) Thieret var. lactea, but other major sources treat that as a synonym for the species name applied here. The common name is also known as Large-leaved Wild Indigo. These plants are erect perennials growing from 3 to 6 feet high with ascending branches. The leaf is trifoliate on a short stalk. In early summer a tall flowering raceme rises above the upper leaves. The flowers with white corollas are typical pea-type with 2 lateral petals, 2 keel petals and a large upper banner. Large insects like bumblebees are required for pollination. Seeds are formed in an oblong inflated pod that turns black at maturity. This splits open at maturity to release the brown kidney shaped seeds. The plant needs full sun, moist to somewhat dry conditions, but does not adapt as well to a home garden as does the Blue False Indigo, B. australis. Eloise Butler planted seeds of the species in 1925 and it was planted later after the Upland Garden was added. The plants range in the state is now restricted to the SE river corridor from the metro south plus a few other SE Counties - remnants of the tall grass prairie. [Back to top plant list]