Ononis, commonly called restharrows (or, archaically, wrestharrows), is a genus of 80 to 90 species of perennial herbs and subshrubs in the legume family Fabaceae. Plants are typically low-growing, reaching around 0.6 metres in height with a spread of up to 1 metre. They produce hermaphroditic flowers from June through September, with seeds ripening between August and October. As members of Fabaceae, restharrows are nitrogen-fixing, enriching the soil and supporting wider ecosystem health. They are also noted for attracting wildlife, particularly serving as larval food plants for several butterfly and moth species, including the grey pug and Coleophora ononidella.
The genus was formally described by Carl Linnaeus in Species Plantarum in 1753. It is placed in the order Fabales, subfamily Faboideae, tribe Trifolieae. Several genus names have been treated as synonyms over time, including Anonis, Bonaga, Bugranopsis, Natrix, and Passaea.
Restharrows are native to Europe, northern and eastern Africa, and western and central Asia. They grow predominantly on dry, calcareous grasslands and are found across Western Europe — including Britain, France, Belgium, and Switzerland — as well as extending into the Mediterranean Basin and further east. In Switzerland alone, ten Ononis taxa are documented, among them O. cristata, O. fruticosa, O. natrix, O. repens, O. rotundifolia, and O. spinosa.
The common name restharrow refers to the plants' characteristically tough roots, which were known to catch and stop agricultural harrows during ploughing, causing the implement to "rest." This same toughness makes mature plants difficult to disturb and best left undisturbed once established.
Etymology
The common name "restharrow" — with the older spelling "wrestharrow" also recorded — refers to the distinctively tough, woody roots of these plants, which were known to catch and hold fast to agricultural harrows during ploughing, bringing the implement to a stop. The genus name Ononis is the Latinised form of the ancient Greek name for the plant; it was taken up by Linnaeus when he formally described the genus in 1753. Several earlier genus names — Anonis, Bonaga, Bugranopsis, Natrix, and Passaea — are now treated as synonyms.
Distribution
Ononis is native to Europe, northern and eastern Africa, and western and central Asia. Within Europe, the genus is particularly well represented around the Mediterranean Basin and extends north into Britain, France, Belgium, and central Europe. In Switzerland, ten taxa are documented, including O. cristata, O. fruticosa, O. minutissima, O. natrix, O. pusilla, O. repens, O. rotundifolia, and O. spinosa (with subspecies spinosa and austriaca). The genus is characteristically associated with dry, calcareous grasslands and disturbed habitats throughout its range.
Ecology
Restharrows are nitrogen-fixing plants, forming symbiotic relationships with soil bacteria to enrich available nitrogen in their habitat. They favour dry, calcareous grasslands and grow well on well-drained, neutral to alkaline soils, including on the tops of walls, dry banks, and other thin-soiled sites. The plants flower from June to September and their flowers attract pollinators. Several Ononis species are important larval food plants for Lepidoptera, including the grey pug moth and the moth Coleophora ononidella.
Cultivation
Restharrows prefer a sunny position in well-drained, neutral to alkaline soil and perform well in locations that many plants find challenging, such as dry banks and wall tops. They are fully hardy across USDA hardiness zones 5 to 9 and tolerate maritime exposure. Once established, mature plants develop very tough root systems and can spread rapidly; they dislike root disturbance and are best planted in their permanent position early. As nitrogen-fixing plants, they can improve soil fertility in the areas where they grow.
Propagation
Seed is the primary propagation method. Seeds can be scarified or pre-soaked in warm water for 24 hours before sowing in spring to improve germination. Division of established clumps is possible in early spring, though plants dislike root disturbance and this should be done with care. Semi-ripe cuttings can also be taken in September and rooted in a cold frame.
Cultural Uses
Restharrows have a long history of use in European folk medicine. The whole herb has been used in the treatment of bladder stones and to subdue delirium, and it has more broadly been applied to conditions involving the bladder, kidneys, and water retention. The active compounds responsible for these properties include essential oils, flavonoid-glycosides, and tannins. Beyond medicine, parts of the plant were historically used as food: the root has a liquorice-like flavour and can be eaten raw or cooked, and when soaked in cold water it makes a refreshing drink. Young shoots were also prepared as a cooked vegetable, brined, or eaten raw in salads.
Taxonomy
Ononis was described by Carl Linnaeus in Species Plantarum in 1753 and is the accepted name for the genus. It is placed in the family Fabaceae, subfamily Faboideae, tribe Trifolieae, order Fabales. GBIF records 262 descendant taxa across the genus. Five genus names are treated as synonyms: Anonis Mill. (1754), Bonaga Medik. (1787), Bugranopsis Pomel (1874), Natrix Moench (1794), and Passaea Adans. (1763). The aggregate taxon Ononis spinosa aggr. is recognised in the Swiss flora, reflecting taxonomic complexity around the O. spinosa group.
