Ononis is a genus of 80–90 species of perennial herbs and subshrubs in the legume family Fabaceae. The members of this genus are called restharrows; an old spelling "wrestharrows" is also recorded from 1965. as some species grow as weeds on arable lands where their tough roots would catch and stop the harrow. The genus is native to Europe, northern and eastern Africa, and western and central Asia.
In herbalism restharrow is used to treat bladder and kidney problems and water retention.
The active ingredients in restharrow are essential oils, flavonoid-glycosides, and tannins.
Restharrows are used as food plants by the larvae of some Lepidoptera species including the grey pug and Coleophora ononidella (which feeds exclusively on O. arvensis).
Species of Ononis
thumb|right|225px|O. arvensis
thumb|right|225px|Ononis natrix, flowers and foliage
The genus Ononis includes the following species accepted by the Plants of the World Online database (POWO), with the addition of one species (O. repens) accepted by the Botanical Society of Britain and Ireland and others (see further below):
- Ononis adenotricha <small>Boiss.</small>
- Ononis afghanica <small>Širj. & Rech.f.</small>
- Ononis alba <small>Poir.</small>
- Ononis alopecuroides <small>L.</small> — foxtail restharrow
- Ononis angustissima <small>Lam.</small>
- Ononis antennata <small>Pomel</small>
- Ononis aragonensis <small>Asso</small>
- Ononis arvensis <small>L.</small> — field restharrow <!-- BiolConserv137:248. -->
- Ononis atlantica <small>Ball</small>
- Ononis aurasiaca <small>Förther & Podlech</small>
- Ononis avellana <small>Pomel</small>
- Ononis azcaratei <small>Devesa</small>
- Ononis baetica <small>Clemente</small>
- Ononis basiadnata <small>Hub.-Mor.</small>
- Ononis biflora <small>Desf.</small>
- Ononis broteroana <small>Ser.</small>
- Ononis catalinae <small>Reyes-Bet. & S.Scholz</small>
- Ononis cephalantha <small>Pomel</small>
- Ononis cephalotes <small>Boiss.</small>
- Ononis christii <small>Bolle</small>
- Ononis cintrana <small>Brot.</small>
- Ononis clausonis <small>(Pomel) Pomel</small>
- Ononis cossoniana <small>Boiss. & Reut.</small>
- Ononis cossoniana <small>Boiss. & Reut.</small>
- Ononis costae <small>Menezes</small>
- Ononis crinita <small>Pomel</small>
- Ononis crispa <small>L.</small>
- Ononis cristata <small>Mill.</small>
- Ononis cuatrecasasii <small>Devesa</small>
- Ononis dentata <small>Sol. ex Lowe</small>
- Ononis diffusa <small>Ten.</small>
- Ononis euphrasiifolia <small>Desf.</small>
- Ononis filicaulis <small>Salzm. ex Boiss.</small>
- Ononis fruticosa <small>L.</small>
- Ononis gines-lopezii <small>Devesa</small>
- Ononis hebecarpa <small>Webb & Berthel.</small>
- Ononis hirta <small>Desf. ex Poir.</small>
- Ononis hispida <small>Desf.</small>
- Ononis incisa <small>Coss. & Durieu ex Batt.</small>
- Ononis intermedia <small>C.A.Mey. ex Rouy</small>
- Ononis jahandiezii <small>Maire & Weiller</small>
- Ononis laxiflora <small>Desf.</small>
- Ononis leucotricha <small>Coss.</small>
- Ononis macrosperma <small>Hub.-Mor.</small>
- Ononis maweana <small>Ball</small>
- Ononis megalostachys <small>Munby</small>
- Ononis minutissima <small>L.</small>
- Ononis mitissima <small>L.</small>
- Ononis mogadorensis <small>Förther & Podlech</small>
- Ononis natrix <small>L.</small> — large yellow restharrow
- Ononis nuristanica <small>Podlech</small>
- Ononis oligophylla <small>Ten.</small>
- Ononis ornithopodioides <small>L.</small>
- Ononis pedicellaris <small>(Batt.) Širj.</small>
- Ononis pendula <small>Desf.</small>
- Ononis peyerimhoffii <small>Batt.</small>
- Ononis phyllocephala <small>Boiss.</small>
- Ononis pinnata <small>Brot.</small>
- Ononis polyphylla <small>Ball</small>
- Ononis polysperma <small>Barratte & Murb.</small>
- Ononis pseudoserotina <small>Batt. & Pit.</small>
- Ononis pubescens <small>L.</small>
- Ononis pusilla <small>L.</small>
- Ononis ramosissima <small>Desf.</small>
- Ononis reclinata <small>L.</small> — small restharrow
- Ononis repens <small>L.</small> — common restharrow
- Ononis reuteri <small>Boiss.</small>
- Ononis rosea <small>Durieu</small>
- Ononis rotundifolia <small>L.</small>
- Ononis serotina <small>Pomel</small>
- Ononis serrata <small>Forssk.</small>
- Ononis sessilifolia <small>Bornm.</small>
- Ononis sicula <small>Guss.</small>
- Ononis sieberi <small>Besser ex DC.</small>
- Ononis speciosa <small>Lag.</small>
- Ononis spinosa <small>L.</small> — spiny restharrow
- Ononis striata <small>Gouan</small>
- Ononis talaverae <small>Devesa & G.López</small>
- Ononis tazaensis <small>Förther & Podlech</small>
- Ononis thomsonii <small>Ball ex Oliv.</small>
- Ononis tournefortii <small>Coss.</small>
- Ononis tridentata <small>L.</small>
- Ononis unifoliolata <small>Dobignard, Jacquemoud & Jeanm.</small>
- Ononis varelae <small>Devesa</small>
- Ononis variegata <small>L.</small>
- Ononis verae <small>Širj.</small>
- Ononis villosissima <small>Desf.</small>
- Ononis viscosa <small>L.</small>
- Ononis zygantha <small>Maire & Wilczek</small>
The status of Ononis repens is disputed; POWO treats it as a subspecies of O. spinosa (as O. spinosa subsp. procurrens <small>(Wallr.) Briq.</small>), while accepting O. arvensis as a separate species. It remains widely accepted as a species, particularly in Great Britain and Ireland, where it is the most widespread and abundant species in the genus.