Roadside Agrimony is a native erect perennial growing from 15 inches to 4 feet high on stems that are usually unbranched and that may have glistening glandular hairs, some soft hair in the upper stem parts and some scattered erect, 2mm stiff hair in lower parts.
The leaves are pinnately-divided into 3 to 11 coarse toothed leaflets, of uniform shape; except for the terminal leaflet, which is the largest, the leaflets are paired. The leaflets are smaller toward the base of the leaf and there are 1 to 4 pairs of minor secondary leaflets in between regular leaflet pairs on the larger leaves. (See photo below.) Upper leaves have fewer leaflets, lower stem leaves have the most leaflets. Each leaflet is elliptic to rhombic (diamond like) in shape. The tips are pointed to long-pointed. The upper surface of the leaflet is a dark green, without hair, and the underside is paler with glistening glandular hair, shorter fine soft hair and scattered stiff hairs that are most prominent along the veins. Veining is conspicuous. Each leaf has a stipule at the stem end that appears somewhat hooked and if it has teeth. These hooks are only on the base end of the stipule.
The inflorescence is a spike-like raceme, held above the leaves, of short-stalked flowers that are usually sub-opposite on the raceme. The raceme stalk is also hairy with glandular hair in the axils and finer soft hair throughout with some scattered stiff erect hair. At flowering time the raceme tends to lean over.
Flowers: Each flower is very small, about 1/3 inch wide when open, with a yellow corolla of 5 petals that spread outward, each petal slightly notched at the rounded tip. There are 5 to 15 stamens (usually around 10) ending in yellow anthers (orange at maturity). Two carpels have 2 styles that protrude from a yellowish nectar ring (an annular disc) in the center. The calyx has five green pointed sepals. Small leaf-like bracts subtend each flower.
Seed: Once the flower is pollinated, the fruiting hypanthia elongates. In shape it is obconic to campanulate (bell-shaped), rarely turbinate, green initially; the top is surrounded at the widest center diameter by a fringe of 3 to 4 rows of long hooked bristles, the lowest row spreading to about 90 degrees. The hypanthia itself is 2.1 to 6.6 mm long and 2.4 to 5.2 mm wide, flat on top, glandular hairs on the surface, which may be glistening. It is deeply grooved and the ridges are sparsely hairy, The seeds are achenes and as the seed forms, the head nods downward. In the fall the hooked bristles become tough and stick to clothing.
Habitat: Roadside Agrimony grows from a fibrous, non-tuberous root system along open space edges and in open spaces in deciduous woods, preferring somewhat fertile soils and partial sun. It will grow in full sun as long as moisture is available.
Names: The genus name, is thought to be from the Greek argemone, and refers to plants that provided healing of the eyes. The basis of this is probably from another species, quite prevalent in Britain and Europe, A. eupatoria, which has a long medicinal and practical use history in Europe. The species name, striata, means 'striped' and refers to the ridges between the deep grooves of the hypanthia.
The author name for the plant classification, ‘Michx.’ refers to Andre Michaux (1746-1802), French botanist 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.
Comparisons: Three species of Agrimony are found in Minnesota and all resemble each other - A. gryposepala, A. pubescens and A. striata. A. gryposepala, Tall Hairy Agrimony, is much taller - to 5 feet high - and the stems always have long glistening glandular hairs, whereas the other two species are shorter and are usually with non-glistening, short, downy glandular stem hairs. A. pubescens, Soft Agrimony, has leaf undersides that rarely have glistening glandular hair; the fruiting hypanthia is turbinate to campanulate in shape; and the leaf stipules have dentate edges. Whereas, A. striata, Roadside Agrimony, may have some glistening glandular hair on the stem, has leaf undersides glistening with sessile or stalked glandular hairs, and the fruiting hypanthia is obconic to campanulate, rarely turbinate. The leaf stipule has dentate edges only at the base or is without any dentate edges.
Above: The inflorescence is a tall spike (raceme) with flowers sub-opposite each other and closely spaced except for a few at the base of the spike. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - the upper stem leaves have fewer leaflets than those below and are placed well below the flowering raceme. 2nd photo - The yellow corolla has 5 petals that spread outward, each petal slightly notched at the rounded tip. There are 5 to 15 stamens (usually around 10) ending in yellow anthers (orange when mature) and 2 styles (from two carpels) that protrude from a yellowish nectar ring (an annular disc) in the center.
Below: The fruiting hypanthia - note the deep grooves and ridges, fine hair on all. 1st photo - note the base ring of hooked bristles spreading out about 90 degrees.
Below: A stem leaf - note the rhombic shape of the major leaflets and the pairs of minor leaflets.
Below: 1st photo - the underside of a leaf - in the photo the glistening glandular hairs show up as small whitish dots - these are more clear with a 10x lens. 2nd photo - a lower stem section.
Below: A comparison of the leaf stipules - 1st photo - A. striata; 2nd photo - A. pubescens.
Below: Note the racemes tend to lean over when heavy with flowers.
In North America, Roadside Agrimony is found in all the lower Canadian Provinces, in most of the northern states of the U.S. from the Rocky Mountains eastward to the coast and up into New England. In the Rockies, it extends southward along the mountain chain.
A. striata, Roadside Agrimony, is the most common species native to Minnesota. It is found more often in the eastern half of the state and occasionally in a few western counties. Both A. gryposepala and A. pubescens are also native to Minnesota, but A. pubescens is the least documented - populations reported by the DNR in only six counties and A. gryposepala in 16 counties. A. pubescens is the only Agrimony listed on the Eloise Butler Wildflower Garden census.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"