Ornithopus sativus Brot.
Summary:A low growing, sprawling, hairy annual legume with leaves divided into 5-18 pairs of narrow leaflets. It has stalked head-like clusters of pink to white pea flowers, 6-8 mm long, in spring. The seed pods are straight or slightly curved, narrow but very compressed and distinctly constricted between the seeds to be almost like a string of beads and separate at maturity into single-seeded units.
Native to Europe or the Mediterranean region but have become weeds along roadsides, particularly in wetlands.
Leaves:With 5-18 pairs of leaflets.
Stipules - Small and membranous on the main leaf, no stipules on the leaflets.
Petiole - On the main leaf only.
Blade - Leaflets, oval, 3-10 mm long x 1.5-4 mm wide with convex sides, sparsely hairy, rounded tip with a tiny point.
Stems: Low lying, sprawling or bending upwards at the ends, 500 mm long. Hairy.
Flower head:On stalks in leaf axils, 2-5 flowered. With a floral leaf with leaflets underneath.
Flowers: Pink or white, pea type.
Bracts - Tiny
Ovary - Stalkless. Many ovules. Style bent inwards, Stigma flat topped.
Sepals - 4 mm long, tubular ribbed near the base, 5 narrowly triangular lobes on top about 2 mm long with acute tips. Tube is 2 mm long. Hairy.
Petals - Pink or white. Standard 7-8 mm long. Limb narrowly oblong or egg shaped. Wings 5-6 mm long. Keel 3-4 mm long, straight, obtuse tip.
Stamens - In 2 groups. Filaments of each group joined. Alternate filaments swollen near the tip.
Anthers - All the same.
Fruit:Very flattened, narrowly oblong pod, 10-25 mm long, stalkless with a network pattern on the surface. Straight or slightly curved. Hairless or with short hairs. Constricted between the seeds to almost like a string of beads. Pod does not release seed when ripe, it breaks crosswise into single seeded segments.
Seeds:No persistent enlarged seed stalk (funicle or aril) where the seed joins the pod.
Roots:Taproot and laterals with nitrogen fixing nodules.
Key Characters:Hairy. Annual. Flower head subtended by a pinnate floral leaf. Flowers pink or white. Calyx lobes 2-2.5 mm long and as long as the tube. Pod distinctly constricted between the segments and break into single seeded segments.
From Judy Wheeler, Flora of the Perth Region and John Moore.
Annual. Seeds germinate in autumn and the plant grows through winter and spring to flower in October and die with the onset of high temperatures and summer drought.
Physiology:Fixes atmospheric nitrogen.
Flowering times:October in Perth.
Seed Biology and Germination:Produces hard or dormant seed.
Seed may need scarification to achieve high germination levels.
Population Dynamics and Dispersal:
Spread by seed. Passes through stock in a viable condition.
Origin and History:Mediterranean. Spain. Portugal.
Distribution:NSW, TAS, VIC, WA.
Courtesy Australia's Virtual Herbarium.
Detrimental:Weed of crops, roadsides, bushland and disturbed areas.
Toxicity:Not recorded as toxic.
Management and Control:Thresholds:
10-30 plants/m2 are usually worth spraying in grass or cereal crops.
Eradication strategies:Exclude stock to reduce the dispersal of seed.
Hand pull odd plants in winter before flowering. For small infestations and grass dominant areas an annual application of 10 mL Tordon®75-D in 10 L water in early winter gives excellent control of existing plants and has residual activity to control later seedlings. 200 mL/ha Lontrel®750 or 50 g/ha Logran® applied in early winter provides reasonably selective control in bushland areas. For hand spraying use 25 mL wetting agent plus 4 g Lontrel®750 or 1 g Logran® in 10 L water. Repeat annually for several years. Metsulfuron(600g/kg) also provides good control at 5 g/ha but is less selective.
Plant tall growing perennial species to reduce re-invasion.
It is relatively tolerant to glyphosate, grazing and mowing.
Other sulfonylurea herbicides also provide good control.
Herbicide resistance:Relatively tolerant to glyphosate and bipyridyl herbicides.
Biological Control:Related plants:
Slender Serradella (Ornithopus pinnatus) is almost hairless with yellow flowers and a narrowly cylindric seed pod. It is widespread in WA.
Yellow Serradella (Ornithopus compressus) is a greyish hairy plant with yellow flowers and a narrow but compressed seed pod but scarcely constricted between the seeds. . It is widespread in WA.
Plants of similar appearance:Clovers, Medics, Lotus, Trefoils, Vetch, Lathyrus.
References:Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P156.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #909.3.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P288.
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