Japanese barberry (Berberis thunbergii) is an exotic, invasive, thorny shrub. It is native to Japan and has been cultivated around the world as an ornamental. It was introduced into North America in the 1800s where it occasionally escapes cultivation. It is now common from Maine to Minnesota south to North Carolina and Missouri, with scattered populations in the west. In Minnesota it is common in the eastern half of the state with scattered populations in the western half. It is found in open, bottomland and upland woodlands; woodland edges and openings; pastures, meadows, and old fields; and roadsides and other disturbed places. It grows in well-drained, moist to dry soil under full sun to medium shade. It is a restricted noxious weed in Minnesota. The state recognizes – and prohibits – 25 cultivars in addition to the parent species.
Japanese barberry is a dense, compact shrub that sometimes forms large, impenetrable thickets. The shrubs are usually no more than 3′ tall but can be much taller. The narrow, spatula-shaped leaves appear in tight clusters on short shoots along the stems and branches. There is a single, half-inch long spine at the base of each leafy shoot. In May and early June clusters of 1 to 5 small yellow flowers appear at at the ends of the shoots. These are replaced in late summer by bright red juicy berries. The berries remain on the plant throughout the winter.
Tall beggarticks (Bidens vulgata) is a common, widespread, native but often weedy wildflower. It is native to Europe and North America. It occurs across the United States but is most common in New England, the upper Midwest, and the Pacific Northwest. It is common in Minnesota. It grows in loamy or silty soil, under full sun to partial shade, in wet to moderately moist sites. It is found on the banks of rivers and streams; on the margins of lakes and ponds; in wet forests and meadows; and in ditches, railroads, roadsides, and other open disturbed sites. It is weedy in moist disturbed sites.
Tall beggarticks is a robust annual with an inconspicuous inflorescence. It is usually 12″ to 20″ tall but in favorable conditions it can reach 60″ or more in height. The leaves are divided onto 3 or 5 leaflets. At the base of each flower head there is a whorl of 10 to 21 modified leaves (bracts). The flower head has up to 150 yellow disk florets and either no ray florets or just 1 to 5 small yellow ray florets.
Lewis flax (Linum lewisii var. lewisii) is an uncommon, non-native, prairie wildflower. It is native to western North America as far east as North Dakota. It is uncommon in Minnesota where it is considered adventive—it is not fully established and the populations in the state may not be self-sustaining. The first recorded observation in Minnesota was in 1959. It continues to spread as it is often included in seed mixes used on prairie restorations.
Lewis flax is semi-evergreen, with at least some foliage remaining green throughout the winter. Flowers are not produced until the third year or, if conditions are favorable, the end of the second year. Bright blue flowers appear from May to July. The petals open at sunrise and fall off by late afternoon.
Dwarf raspberry (Rubus pubescens) is a perennial, low-growing, non-woody subshrub. In the United States it occurs in the northern tier of states south to New Jersey, Colorado, and Oregon. In Minnesota it is common throughout most of the state but absent in the west-central, southwest, and south-central counties. It is found in moist to wet woodlands and meadows and in various wetlands including shrubby swamps, bogs, and fens.
Short, erect, leafy stems rise from a creeping runner that can be up to 80″ long. The 2 to 5 leaves are each divided into three leaflets. In mid-May to late June 1 to 4 small white flowers appear at the end of the stem. In early to mid-summer, each flower is replaced by a small, bright red to dark red fruit. The fruit is tasty but small, and it does not easily separate from its core.
Narrow-leaved vervain (Verbena simplex) is a 4″ to 27½″ tall, erect, perennial forb. It grows in full sun in moderately dry to dry soil in upland prairies, hill prairies and old fields; on roadsides and railroad rights-of-way; and in other open, disturbed areas. It occurs in the United States from New Hampshire to Minnesota south to Texas and Florida, and in adjacent Canadian provinces. In Minnesota, where it is at the northwestern extent of its range, it has been recorded in only five counties. In two of those counties, the records are historical, and it is now presumed to be locally extinct (extirpated). It is listed as a special concern species in both Minnesota and Wisconsin.
Narrow-leaved vervain has one or more stems, narrow leaves, and a spiked inflorescence. The flowers are lavender or purple to white, or white tinged with blue, rarely white. Compared with the other three species of vervain found in Minnesota, narrow-leaved vervain is much rarer, is a much smaller plant, and has much narrower leaves.
Tall thistle (Cirsium altissimum) is a robust native plant. It can be 4′ to 10′ tall but in Minnesota it is usually no more than 7′ in height. It is found in prairies, open woodlands, roadsides, and disturbed sites. It has a patchy distribution in the lower two-thirds of Minnesota and is never common. It is absent from the far north and the Arrowhead region.
Tall thistle will easily pass the Native Thistle Test. Grasp the stem near the base of any native thistle loosely in your fist, then slide your fist upwards to just below the inflorescence. If the plant is a native thistle, you will not get a single prickle – it will be “ouchless”. If the thistle is thought to be an exotic (non-native) species, this test is not recommended.
Tall thistle looks similar to other native thistles. It can be distinguished by the stem that is green and not spiny; and the leaves that are white on the underside and are either unlobed or shallowly lobed.
Prickly tree clubmoss (Dendrolycopodium dendroideum) is an erect, evergreen, perennial, low-growing plant that looks like a miniature coniferous tree. It grows in northern forests and in shrubby areas recovering from fire or other disturbance. It often forms large colonies. In Minnesota it is common in the northeast, infrequent in the southeast, and mostly absent from the south and west.
Prickly tree clubmoss is usually no more than 6″ in height and has widely spreading branches. The branches are themselves up to four times branched—most branches have two or more secondary branches (branchlets), those branchlets are usually branched, those branchlets are often branched, and those branchlets are sometimes branched. The stem and branches are densely covered with prickly, needle-like leaves. Each fertile plant has 1 to 7 spore-bearing cones.
Several other Minnesota clubmosses are very similar in appearance. Prickly tree clubmoss is distinguished by lateral branches that are round in cross section, not flattened; stiff, prickly, widely spreading leaves on the lower part of the stem; and leaves on the branches that are all equal in size and arranged in six ranks, 2 above, 2 below, and one on each side.
There are 76 species of Lycopodium worldwide. Only two of them occur in Minnesota. Running clubmoss (Lycopodium clavatum) is very widespread and common. It has a worldwide distribution, occurring on every continent except Australia and Antarctica. It is common in Minnesota in the Arrowhead region, infrequent in the north-central and central regions as far south as the northern metro, infrequent in the driftless area in the southeast, and absent from the remainder of the state.
Running clubmoss is an evergreen, perennial club moss. It produces a very long, creeping, horizontal stem and clusters of upright, branched stems. The stems are densely covered with narrow leaves that are arranged spirally and have a long hair at the tip.
Running clubmoss looks similar to its close relative, one-cone clubmoss. It can be distinguished by the cones that occur in groups of usually 2 to 5 and are arranged as a straight central axis with spreading to ascending side branches.
Western rock jasmine (Androsace occidentalis) is a small annual forb that occurs in North America between the Rocky Mountains and the Mississippi River. In Minnesota it is occasional in the western, southern, and central regions, absent from the northeast. It may be the smallest terrestrial wildflower native to Minnesota. It is usually no more than 3″ tall. It appears as a 1½″ in diameter radiating cluster of leaves and up to 15 leafless flower stalks. The flowers are white and about 1 ⁄16″ wide.
Western rock jasmine is short-lived, flowering from April to May and dying back by mid-summer. It is easily overlooked due to its diminutive size. For these reasons it may be more common than reported.
There are seventeen species of Diphasiastrum worldwide, five in North America, two in Minnesota. Fan clubmoss (Diphasiastrum digitatum) is the most abundant Diphasiastrum species in North America. It is common in eastern and north-central Minnesota. It grows in well-drained, moist to dry soil, in dappled sunlight to light shade, in open, upland, coniferous and deciduous woodlands, thickets, and sandy fields.
Fan clubmoss is a low growing shrubby evergreen. It produces both horizontal and erect stems, numerous branches that are held parallel to the ground, and cones at the end of long stalks. It is distinguished from other club mosses by horizontal stems that lie on the surface of the ground; branches that are flattened, are held parallel to the ground, and do not have narrow areas marking the start and end of annual growth; four ranks of leaves, those on the underside much smaller than those on the upper side; and sterile tips on about half of the cones.
Club mosses in the genus Diphasiastrum readily crossbreed with other species in the same genus. The hybrids that are produced are fertile. Fertile hybrids are common in the animal kingdom but rare in the plant kingdom.