Trifolium dubium Sibth.
Synonyms - Trifolium minus.
Trifolium is from the Latin tres meaning 3 and folium meaning leaf and refers to the 3 leaflets.
Other names:Hop Clover
Least Hop Clover
Lesser Yellow Trefoil
Little Hop Clover
Small Hop Clover
Yellow Suckling Clover because it has yellow flowers.
Summary:Suckling Clover is a low lying, hairless to slightly hairy, annual clover with trifoliate, toothed leaves that have the middle leaflet on a longer stalk (like medics) and 4-20 yellow flowers in a loose globular head in spring to early summer.
Native to Europe, it flowers from late winter to summer.
First Leaves:First leaf has only one 'spade' leaflet. Second and later leaves have 3 leaflets.
Leaves: Trifoliate, alternate, widely spaced.
Stipules - 2-5 mm long, slightly shorter than the petiole, minute teeth on the edges, free part is broadly egg shaped. Tip pointed. Tiny hairs.
Petiole - very short, 3-6 mm. Sparsely hairy.
Blade - Of leaflets, narrowly egg shaped to triangular 4-12 mm long x 2.5-7 mm wide, edges toothed near the top. Tip rounded, or flat or with a notch. Hairy to hairless. Middle leaflet has a short stalk whereas side leaflets are stalkless.
Stems: Slender, low lying, drooping or rising at the ends to erect, up to 500 mm long. Hairy with low lying hairs to hairless. Branched or unbranched.
Flower head:In leaf axils on stalks (peduncles) longer than the leaf. Loose globular, 5-9 mm diameter, 4-20 flowered which turn brown with age.
Flowers:Yellow, pea like on stalks (pedicels) shorter than the calyx tube. Pedicels turned downwards after flowering.
Calyx - 1.5-2 mm long, tube 0.5-1 mm long, 5 veined. Hairy to hairless. Throat open and hairless inside. 5 lobes of different lengths, 2 upper ones shorter and more pointed than the 3 lower ones, narrowly triangular about 1 mm long, sparsely hairy. Bent back after flowering.
Petals - Yellow, 3-4 mm long. Limb of standard egg shaped. Standard petal 3-4 times as long as calyx tube, faintly striped and folded lengthwise around the developing pod, smooth and scarcely furrowed. Wings held close together. Keel slightly shorter than the wings with an obtuse tip. Petals turn dark brown as the fruit matures.
Stamens - 10 with 9 in a group.
Fruit:Oblong, single seeded pod, 2 mm long x 1.5 mm wide. Not hidden in the calyx but enclosed within the dried flower.
Seeds:Pale brown, oval, 1-1.5 mm long.
Roots:Taproot and many laterals. Nitrogen fixing nodules.
Key Characters:4-20 yellow flowers in a loose globular head. Pedicels shorter than calyx tube. Standard petal scarcely furrowed. Calyx 5 nerved, the throat open and glabrous inside. Pod 1 seeded, shortly stipitate. Style very short. Middle leaflet has tiny stalk.
Annual. Germinates in autumn and grows during the cooler months with a flush of growth in spring. Flowers August to December and dies with the onset of hot weather.
Physiology:Has symbiotic rhizobia in nodules on the roots that fix atmospheric nitrogen.
Flowering times:Spring to early summer in western NSW.
Flowers September to December in SA.
August to November in Perth.
Spring in WA.
Seed Biology and Germination:Vegetative Propagules:
Hybrids:Varieties in WA and the ACT appear to be somewhat less hairy than in other states.
Allelopathy:Population Dynamics and Dispersal:
Spread by seed.
Tends to be present as a minor component of pastures.
Origin and History:Europe.
Distribution:ACT, NSW, QLD, SA, TAS, VIC, WA.
Courtesy Australia's Virtual Herbarium.
Grassland, open woodland.
Fodder - provides palatable early spring feed but is a poor producer and has a low leaf to stem ratio.
Detrimental:Weed of crops, vegetables, cultivated ground, crops, pastures, lawns, gardens and disturbed areas.
Toxicity:Not recorded as toxic.
Management and Control:Dicamba and sulfonylurea herbicides provide good control.
Prevent seed set for 5 years.
Exclude stock to prevent dispersal of seed and burrs.
Hand pull isolated 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 seedlings.
In bushland, 200 g/ha Lontrel®750 or 50 g/ha Logran® applied in early winter provides reasonably selective control. Use 25 mL wetting agent plus 4 g Lontrel®750 or 1 g Logran® or 0.1 g metsulfuron(600g/L) or 0.1 g chlorsulfuron(750g/kg) in 10 L water for hand spraying when they are actively growing. Repeat annually for several years. Plant tall growing perennial species to reduce re-invasion.
Clovers are relatively tolerant to glyphosate, grazing and mowing.
Herbicide resistance:Biological Control:
Alsike Clover (Trifolium hybridum)
Arrowleaf Clover (Trifolium vesiculosum)
Balansa Clover (Trifolium balansae)
Berseem Clover (Trifolium alexandrinum)
Birdsfoot Trefoil (Trifolium ornithopodioides)
Bladder Clover (Trifolium spumosum)
Caucasian Clover (Trifolium ambiguum)
Cluster Clover, Ball Clover (Trifolium glomeratum) is a ground-hugging plant with broad leaflets, 5-22 mm long, and globular heads of pink flowers.
Crimson Clover (Trifolium incarnatum)
Cupped Clover (Trifolium cherleri)
Drooping flowered Clover (Trifolium cernuum)
Gland Clover (Trifolium glanduliferum)
Globe Clover (Trifolium globosum)
Hop Clover (Trifolium campestre) is a sprawling plant with fairly broad leaflets, 4-15 mm long, and globular to ovoid heads of yellow flowers. The standard petal is not furrowed and it has 20-50 flowers in the head.
Hare's Foot Clover (Trifolium arvense) is an erect or sprawling plant with narrow leaflets 5-20 mm long and ovoid to shortly cylindric heads of pink flowers.
Kenya White Clover (Trifolium semipilosum)
Knotted Clover (Trifolium striatum)
Lappa Clover (Trifolium lappaceum)
Ligurian Clover (Trifolium ligusticum)
Narrow-leaved Clover (Trifolium angustifolium) is an erect plant with long narrow leaflets, 15-75 mm long, and cylindric heads of pink flowers.
Purple Clover (Trifolium purpureum)
Red Clover (Trifolium pratense)
Rose Clover (Trifolium hirtum) is a hairy plant with fairly broad leaflets, 10-25 mm long, and globular to semi-globular heads of pink to purple flowers.
Rough Clover (Trifolium scabrum)
Sea Clover (Trifolium squamosum)
Shaftal Clover (Trifolium resupinatum)
Slender Suckling Clover (Trifolium micranthum)
Star Clover (Trifolium stellatum)
Strawberry Clover (Trifolium fragiferum)
Subterranean Clover (Trifolium subterraneum) is a ground-hugging plant with broad leaflets, 6-22 mm long, and few-flowered heads of white flowers that form globular buried burrs.
Suckling Clover (Trifolium dubium) is a ground-hugging plant with loose globular heads of yellow flowers and fairly broad leaflets, 4-12 mm long and the end leaflet has a short stalk.
Suffocated Clover (Trifolium suffocatum)
White Clover (Trifolium repens) is a ground-hugging plant with broad leaflets, 4-12 mm long, which often have a pale v-shaped band and globular heads of white flowers.
Woolly Clover (Trifolium tomentosum) is a sprawling plant with broad leaflets, 4-13 mm long and globular heads of pink flowers which become woolly with age.
Zigzag Clover (Trifolium medium)
Plants of similar appearance:Hop Clover looks very similar.
Wood sorrel, Medics, Trefoils, Oxalis spp.
References:Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P452. Diagram.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P221.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P426. Photo.
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). P158-160. Photo.
Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P104-105. Diagram.
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). #1228.9
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). P303.
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