1. Agrimonia L. (agrimony)

Plants perennial herbs, lacking spines and thorns, with short usually knotty rhizomes. Stems erect or ascending. Leaves alternate and often also basal, pinnately compound with small leaflets interspersed among the larger primary ones, short-petiolate, the leaf blade elliptic to broadly obovate in overall outline, the leaflets with the margins coarsely toothed. Stipules leaflike, the pair at each node fused to the petiole toward the base (those of basal leaves fused most of their length with only the slender tips free), lanceolate to broadly and asymmetrically ovate, rounded or somewhat cordate at the base, the outer margin with several lobes or coarse teeth (sometimes more finely toothed in A. rostellata). Inflorescences terminal, spikelike racemes, the flower stalks very short, each subtended by a small deeply lobed bract (the hypanthium also subtended by a pair of inconspicuous 3-lobed bractlets). Flowers ascending, becoming spreading to reflexed as the fruits mature, perigynous, the hypanthium appearing obconic, deeply cup-shaped with a nectar disc nearly closing the opening, armed with dense hooked bristles toward the rim, developing 10 longitudinal ridges and grooves as the fruits mature. Sepals 5, short, oblong-elliptic, spreading at flowering, becoming erect or somewhat incurved with age and developing into a small beak on the fruit. Petals 5, 2–6 mm long, broadly elliptic to nearly circular, yellow. Stamens 5–15. Pistils 2 per flower. Ovaries superior, hidden in the hypanthium, with 1 ovule. Style 1 per ovary, terminal, the stigma somewhat 2-lobed. Fruits consisting of the hardened obconic hypanthium containing 1(2) small globose to somewhat ovoid achene, the hooked bristles becoming somewhat elongated and hardened. About 18 species, North America, South America, Europe, Asia.

The fruits of Agrimonia species are dispersed when the hooked bristles along the hypanthium margin become entangled in the fur (or clothing) of passing mammals. The glands referred to in the key and descriptions are somewhat sticky and resinous, sessile, yellow to yellowish brown (sometimes darkening upon drying), and globose to depressed-globose on inflorescence axes. When present on leaflets, they appear often flattened or even impressed, especially when dried.

Species of agrimony were used medicinally by various tribes of Native Americans, mostly for intestinal problems, particularly diarrhea. Bush (1916) and Palmer and Steyermark (1935) reported specimens of A. microcarpa Wallr. (low agrimony) from various parts of Missouri, many of these under the name A. platycarpa Wallr., which is now considered a synonym of the former species. Steyermark (1963) excluded this species from the flora, stating that the specimens actually represented a mixture of A. pubescens and A. rostellata. Agrimonia microcarpa grows to the east and south of Missouri and differs from other Missouri agrimonies most noticeably in its leaves with usually only 3 primary leaflets.