Forage Focus - Equine - August 2009 Identification of Legumes by Krishona Martinson, University of Minnesota Correct identification of legumes in hay fields and pastures is important when making agronomic decisions. Although legumes are much easier to identify when flowering, identifying legumes in vegetative stages is possible when key and unique leaf features are known. In order to identify vegetative legumes, one must consider the number of leaflets that make up the leaf, leaf margins, stipules, and petioles. Most legumes have three leaflets; an exception is birdsfoot trefoil which has five. Leaf margins can be serrated (toothed) or entire (smooth). Stipules are a growth at the base of petioles, and the petiole connects the leaflets to the stem. All true clover leaflets are attached to the petiole at the same point. Alfalfa and sweetclover leaflets are attached to the petiole via a petiolule. Sweetclover is not a true clover because of the petiolule. Red, white, and alsike clovers are true clovers. Table 1 provides additional agronomic information. Table 2 (page 7) further outlines how to identify commonly found legumes and briefly describes their agronomic characteristics. Table 2. Agronomic characteristics of commonly found legumes. Life Cycle & Identifying Other Identifying Agronomic Species Leaf* Flower* Growth Habit Characteristics Characteristics Characteristics Requires a soil pH of Trifoliate leaf. Serrated 6.5-7.0, high soil fertility; edges only on upper ⅓-½ Stipules have marginal Alfalfa Perennial cannot withstand water of leaflet; pubescent on teeth and sharply logged soils or flooding. (Medicago sativa) Upright underside. Blue or pointed tip. Can cause photosensitivity purple flowers. in horses. Yellow sweetclover has Trifoliate leaf. Leaflets yellow flowers. White Sweetclover Perennial have serrated edges Stipules small with smooth sweetclover has white extending almost to base. edges. Sweetclover is not a flowers. Can cause (Melilotus species) Upright Leaflets are smooth on true clover. bleeding in livestock if underside. sweetclover becomes moldy in hay. Best suited for poorly Trifoliate leaf. Leaflets V-shaped watermark drained areas. Not Red Clover Perennial are hairy and not toothed. always present, not always recommended for hay (Trifolium pratense) Upright Hairy stems; red or distinct. Young leaflets production. Can cause purple flowers. tend to be heart-shaped. photosensitivity and slobbers in horses. Trifoliate leaf. Leaflets V-shaped watermark have serrated edges from present, not always distinct. White Clover Perennial tip to base. Stems and Young leaflets tend to be Not recommended for hay Upright (small stature) leaflets do not have hair. heart-shaped. Intermediate production. Can cause (Trifolium repens) and spreading Leaflets are shiny on sized stipules. Reproduces photosensitivity in horses. underside. White to and spreads from stolons pink flowers. (above ground stems). Trifoliate leaf. Finely- Alsike Clover Perennial serrated leaflet edges. Leaflets lack inverted Not recommended for hay Leaflet and stems smooth. V-shaped watermark. production. Can cause (Trifolium hybridum) Upright Leaflets dull on underside. Stipules are large. photosensitivity in horses. White to pink flowers. Trifoliate leaf. Leaflets V-shaped watermark and stems are not hairy but Has great persistence always present, not always Kura Clover Perennial leaflet margins are acutely under grazing. Very winter distinct. Reproduces and serrated at the edges. hardy. Can be difficult (Trifolium ambiguum) Upright and spreading spreads from rhizomes Leaflets are oblong; white to establish. (underground stems). to pink flowers. Best suited for acidic, Commonly used by Five leaflets per leaf, three poorly drained soils. highway departments for Birdsfoot Trefoil Perennial in a trifoliate at the tip of Provides high quality roadside seeding. Can be leaf blade and two at base. forage, even at or after (Lotus corniculatus) Prostrate difficult to establish, but No hair. Yellow flowers. maturity. Does not cause persists via reseeding. bloat in cattle. Pinnately compound. 8-12 Can be confused with hairy Primarily used for soil pairs of opposite leaflets vetch (purple flowers with improvement, along Cow Vetch Perennial with apical tendril. Blue- lower white flowers), and roadsides, and for bank violet to purple flowers; (Vicia cracca) Prostrate vine crown vetch (pink-purple stabilization. Suitable for arranged in a crowded, flowers in crown shape). dry, sandy soils. one-sided arrangement. Strong stand persistence. Pinnately compound. 8-17 Very winter hardy. Can Perennial pairs of opposite leaflets. Cicer Milkvetch Reproduces and spreads be difficult to establish. Yellow to white flowers. Somewhat upright to by rhizomes. Reduced voluntary intake (Astragalus cicer) Flowers originate in prostrate vine (palatability) can leaf axils. be observed. *Photograph credits: Krishona Martinson, University of Minnesota (all except alsike clover leaf and flower) and the University of Minnesota Stand Memorial Herbarium (alsike clover leaf and flower)..