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.
Shinleaf (Pyrola elliptica), also called elliptic shinleaf, is a common and widespread, up to 10½″ tall woodland wildflower. It occurs across northern United States and southern Canada, and in Arizona and New Mexico. It is common in Minnesota. It grows under dappled shade in acidic, nutrient-poor, well-drained soil in moist areas of upland forests and woodlands. Because it grows in nutrient poor areas, shinleaf depends in mycorrhizal fungi on its roots for nutrients. It cannot survive in the absence of this fungi.
Shinleaf appears as a single, unbranched, flowering stalk with a cluster of leaves at the base. The leaves appear basal but are actually alternate and very closely spaced at the base of the stem. Up to 21 white flowers bloom at the top of the stem from June to August. The flowers hang downward and have a conspicuous, curved, pale green style hanging below.
Shinleaf is distinguished by elliptic or oblong leaves without whitened veins; the cluster of up to 21 flowers; the white to greenish-white petals; and the long, curved, protruding style.
Lily-leaved twayblade (Liparis liliifolia), a common orchid in eastern United States, is scattered to rare in Minnesota. It is found from the driftless area in the southeast to just north of the St. Cloud area, with isolated populations in Itasca and Watonwan Counties. It grows in open woodlands, small woodland openings, and along woodland trails, where it gets partial sun or light shade. It is declining in Minnesota due to loss of habitat and to forest management practices. It has been recorded historically, but is no longer found, in Wright, Sherburne, and Anoka Counties. It may be decreasing in part due to fire suppression and forest succession, as oak forest is overtaken by maples and basswood, becoming more densely shaded.
Lily-leaved twayblade has two large, lily-like leaves at the base; a single, leafless, 10″ tall, flowering stem; and a loose, unbranched cluster of up to 31 flowers. The flowers are brownish-purple and have a spidery appearance. The sepals are green, long, and very narrow. The side petals are long, very narrow to thread-like, and hang downward. During development the flower twists 180° so that, when mature, the upper petal (lip) appears to be the lower. The lip is brownish-purple and more or less flat. After the flowers drop off in late summer the cluster of erect, green, seed capsules at the end of a bare green stem rising from persistent green basal leaves is distinctive.
Cream pea (Lathyrus ochroleucus) is a low vine that is common in Minnesota except for the southwest quarter of the state. It is found in open woodlands, woodland openings, trailsides, riverbanks, and thickets.
The leaves of cream pea are divided into 3 to 5 widely-spaced pairs of large leaflets. At the end of each leaf there is a slender tendril, and at the base there is a pair of small, leaf-like appendages (stipules). The stipules are rounded at the base and sharply pointed at the tip, appearing half heart-shaped. The shape is distinctive, and can be used to identify the plant when no inflorescence is present. From May to July clusters of cream-colored flowers rise from the leaf axils.
Bohemian knotweed (Fallopia × bohemica) is a fertile hybrid between two highly invasive plants, Japanese knotweed and giant knotweed, and it shares features of both of those plants. The hybrid was introduced into North American and cultivated as an ornamental. It escaped from cultivation and is now naturalized across northern United States. It is reported to be partially or fully fertile, but it spreads mostly by rhizomes and by the dispersal of plant fragments.
Bohemian knotweed is found on river banks, along roadways, and in other disturbed areas. It often forms large dense colonies. Its bamboo-like stems are erect, stiff, and hollow, and usually have many long slender branches. The leaves are up to 12″ long and may be spade-shaped, straight across at the base, or slightly heart-shaped, indented at the base. Both leaf shapes may appear on the same branch. Flowers appear from July to October. The inflorescence may be long, narrow, and unbranched, or short, broad, branched, and plume-like, and it may be either shorter or longer than the nearest leaf.
Though one parent, Japanese knotweed, is listed as invasive in Minnesota, this hybrid is not … yet.