European bur-reed (Sparganium emersum) is a common plant in northern Minnesota. It is found in shallow water at the margins of lakes and swamps, in ponds and streams, and in backwaters of large rivers. From June to August it produces conspicuous, spherical heads of tiny white flowers.
The spongy leaves rising from the base of the plant may be stiff, erect, and up to 32″ long, or limp, floating, and up to 80″ long. The leaf-like bracts on the flowering stem are smaller and spread outwards or bend upwards.
There are 22 species of bur-reed worldwide, 9 in North America north of Mexico, 6 in Minnesota. European bur-reed is distinguished by its small size; leaves that are flat, not rounded, on the back; unbranched inflorescence with up to 6 pistillate heads; pistillate flowers with a single stigma; and spindle-shaped fruit that tapers to both ends.
When a flowering stem is not present the stiff leaves may be mistaken for narrow-leaved cattail. However, those leaves are rounded on the back, not flat.
Cypress spurge (Euphorbia cyparissias) is native to Europe and western Asia but not to North America. It was imported, cultivated as an ornamental, and sold in nurseries for use in gardens, parks, and graveyards. It escaped cultivation and is now naturalized across the United States and southern Canada. It is considered invasive and is on the state noxious weed list of 46 states including Wisconsin, but does not show up on any list of invasive or noxious species in Minnesota.
The latex exuded by broken stems and leaves of this plant causes a rash in some people similar to that of poison ivy. The plant may be also toxic to cattle and horses.
Cypress spurge is similar in appearance to another invasive plant, leafy spurge (Euphorbia esula). Cypress spurge is a much smaller plant with smaller, very crowded leaves.
Allegheny monkeyflower (Mimulus ringens var. ringens) is a plant of wet places. It is common in meadows, swamps, fens, and marshes, and is also found on streambanks, riverbanks, and in roadside ditches. Between June and August it produces solitary purplish-blue flowers from the axils of the upper leaves.
The genus name Mimulus, from the Greek mimos meaning “imitator”, and the common name “monkeyflower”, refer to red markings on the corolla of some of the yellow species which are said to resemble a monkey’s face.
Rattlesnake master (Eryngium yuccifolium var. yuccifolium) is a common plant of native tallgrass prairies in the eastern United States. Southeastern Minnesota is the northwest extent of its natural range, but very little tallgrass prairie remains in the state. This habitat loss led the Minnesota DNR to list it as a special concern species in 1984.
The common name is derived from its traditional use by Native Americans to treat rattlesnake bite. The plant was also used as a diuretic, a sedative, a pain reliever, a tonic, and for cordage.
This plant is easily identified. The waxy, bluish-green stem and foliage; stiff, grass-like leaves with widely scattered spiny or thread-like teeth; and white, spherical flower heads, combine to create a unique appearance. There are no similar species in Minnesota.
Gray birch (Betula populifolia) is native to eastern United States and Canada as far west as Illinois. It has been recorded in Minnesota only twice, once in Anoka County in 2013 and again in Itasca County in 2015. In its native range it is an early successional tree colonizing burned areas, abandoned pastures, road cuts, and other disturbed areas.
Gray birch is one of the smallest trees in the northeast, usually no more than 30′ tall and about 6″ in diameter at breast height. It is short-lived, seldom surviving more than 50 years. The resemblance of the leaves to those of quaking aspen (Populus deltoides) is the source of the species name populifolia.
Gray birch is easily identified by the aspen-like triangular leaves with flat bases and long, drawn-out tips. It is also distinguished by grayish-white bark that does not easily peel; dark triangular patches at the base of each branch and branch scar; and male catkins that occur individually, not in groups.
Rope dodder (Cuscuta glomerata) is an annual herbaceous vine that parasitizes the above-ground portion of other plants. It is considered a noxious weed in the United States and a restricted weed seed in Minnesota, but is listed as threatened in Florida and is a Special Concern species in Wisconsin.
In the spring a seed produces a single, slender, fast-growing stem, and a single root. The root is for anchoring only. It does not absorb nutrients and withers away after the stem attaches to a host plant. The stem lives solely on the nutrients stored in the embryo. It must find and attach to a host plant in 5 to 10 days or it will die. It seeks a compatible host by detecting and growing toward specific airborne volatile organic compounds. When it encounters another plant it wraps around it. If the plant is a suitable host the dodder stem will produce sucker-like, specialized roots (haustoria) that penetrate and draw nutrients from the host plant’s tissue. As it continues to grow it becomes more robust and climbs the host, twining in a counter-clockwise spiral.
From May to early July rope dodder looks like orange tangled string. In July it produces flowers on parts of the stem that are tightly appressed and attached to a host plant. The inflorescence is a dense, rope-like mass of tiny flowers wound spirally around the stem of the host.
There are at least 7 species of dodder in Minnesota. The dense, rope-like inflorescence distinguishes this from all other dodders.
Blackberry lily (Iris domestica) is a popular garden plant from Asia that has escaped cultivation in North America. It is now widespread in eastern and central United States but scattered and still uncommon. It has been recorded only twice in Minnesota: once, date unknown but prior to 1991, in Waseca, where it was planted and escaped cultivation; and once on 8/8/2014 in Baker Park Reserve in Hennepin County.
The common name of this plant is a misnomer. It is an iris, family Iridaceae, not a lily, family Liliaceae. It gets its name from the lily-like appearance of the flowers and the blackberry-like appearance of the seed clusters. It blooms from June to July and is typically found on hillsides, pastures, woodland openings, thickets, roadsides, old fields, old homesteads, and disturbed areas. The flowers bloom from dawn to dusk and last only a single day.
At different times in its development, blackberry lily is similar in appearance to some of our native lilies and irises. It is distinguished by a combination of the following characteristics: sword-like basal leaves; alternate, overlapping stem leaves; flowers held erect or horizontal, not hanging downward; sepals and petals widely spreading, not curved backward; and clusters of black seeds that look similar to blackberries.
Northern catalpa (Catalpa speciosa) is occasionally seen in suburban front yards but rarely seen in natural areas in Minnesota. That may soon change. Prior to European settlement the range of northern catalpa had contracted to a small area around the confluence of the Mississippi and Ohio Rivers. In the 1930s and 1940s it was widely planted as a windbreak and cultivated for fence posts in Ohio. It is still sold and planted as a shade tree and ornamental because of its large leaves and showy flowers. It has now become naturalized from Kansas to Virginia north to southern Michigan and southern Wisconsin. Its range continues to spread and now includes almost all states east of the Rocky Mountains. In Minnesota it is not fully established but is locally naturalized. It is hardy up to zone 4, which includes the southern half of the state.
Northern catalpa is a medium-sized, moderately fast-growing, moderately short-lived, deciduous tree. It has very large heart-shaped leaves arranged in whorls of three. From May to June it produces large, showy clusters of white flowers. The flowers are fragrant but inhaling their aroma may be poisonous to some individuals. The flowers are replaced in late summer by long, thin, pencil-shaped seedpods. In autumn the leaves turn pale yellowish-green and fall before turning yellowish-brown.
Chinese catalpa (Catalpa ovata) is also found in Minnesota. Northern catalpa is distinguished by unlobed leaves that are densely short-hairy on the underside, larger flowers, and relatively thick-walled seedpods.
Rare in Minnesota, Amur corktree (Phellodendron amurense) is an east Asian tree that was introduced into North America around 1856 and was planted as an ornamental. By 1933 it had become naturalized in the forests of New York. It is now considered a pest tree in New England. When allowed to become established it can create dense stands consisting of a large number of small trees that crowd out native species. It produces massive amounts of berry-like fruits which remain on the tree into early winter. Seeds are spread by American Robins and other birds. It is reported to be invasive in scattered locations in Illinois, Maryland, Massachusetts, New York, Pennsylvania, and Virginia. It is a prohibited species in Massachusetts. It is not listed in Minnesota, probably because of its rarity in the state. To date, it has been reported in just two locations in Minnesota: Lake Minnewashta County Park in Carver county, 9/28/2007; and Whitetail Woods Regional Park in Dakota County, 10/20/2015.
The compound leaves could be mistaken for walnut or ash but on this tree the fruits are clusters of black berries. The most distinguishing feature of Amur corktree, and the feature which gives the tree its common name, is the yellow, spongy or corky, inner bark. The outer bark is also more or less corky, and is distinctive enough in appearance to cause a passing naturalist to stop and investigate this unusual species.
Photo by Peter M. Dzuik
Few-seeded sedge (Carex oligosperma) is found in bogs, sedge meadows, and peaty wetlands. It grows only in acidic soils. It is common in bogs along with woolly-fruit sedge, where the long rhizomes of the two sedges weave together and help create floating vegetative mats. The leaves are wiry, stiff, and no more than ⅛″ wide, giving this plant one of its other common names, wiregrass.
This species is identified by narrow leaves with margins rolled inward; reddish-purple sheaths of basal leaves; lack of cross lines between the veins of the leaf sheath; unisexual flower spikes; and short, plump pistillate spikes with just 3 to 15 spikelets.