Sainfoins are mostly subtropical plants, but their range extends throughout Europe as far north as southern Sweden. These plants grow on grassland, agricultural land and wasteland. The leaves are pinnate, alternate, with 6 to 14 pairs of oblong to linear leaflets. Sainfoins have pale pink flowers, typically blooming between June and September and pollinated by honey bees and solitary bees. The rounded single-seeded pods bear prominent spikes or similar protrusions in many species, enabling them to cling to the fur of large mammals and be thus distributed.
These highly nutritious plants were an important forage for heavy working horses in agriculture, and are still an excellent source of nectar for honey production as well as pollen for bee food. Because sainfoins are rich in tannins which protect proteins from hydrolysis in the rumen, the proteins are instead absorbed in the abomasum. Onobrychis typically have a deep taproot and so are very drought resistant, but do not recover well from overgrazing. Adapted to slow but steady growth in the arid steppe belt of Eurasia, sainfoins are difficult to establish as pasture, are not persistent in grassland, and only yield one crop of hay or seeds per year. Thus they are seldom grown in any significant extent, though O. viciifolia is met with somewhat more regularly.