Sharp Buttercup

Ranunculus muricatus L.

Family: Ranunculaceae.

Names:

Ranunculus is Latin for tadpole from the Latin rana meaning frog and may refer to the damp habitats preferred by many species in this genus.
Muricatus means rough and refers to the rough faces of the seed (achene).
Sharp Buttercup because the seed are pointed and sharp to touch and it has butter yellow, cupped flowers.

Other names:

Burr Buttercup
Rough Fruited Buttercup
Rough Seeded Buttercup.

Summary:

An almost hairless annual herb with circular, lobed leaves on long petioles and shiny, yellow 'buttercup' flowers from September to December with usually 5 petals that don't overlap and many sharp seeds in globular heads.

Description:

Cotyledons:

Two. The blade is oval, with obvious veins, 8 to 12 mm long with a pointed tip and a tapering base. The stalk is slightly shorter than the blade. Hairless. The seedling has a very short hypocotyl and no epicotyl.

First Leaves:

The leaves develop singly, the first being 6 to 8 mm long in the blade with a petiole about half this length. The first leaf is circular in outline, notched at the base, obtuse tipped and has a terminal plus 2-6 lateral lobes but as the plant grows the leaves tend to become three lobed with the lobes themselves much divided. Hairless.

Leaves:

Alternate. Form a rosette.
Stipules - None.
Petiole - 25-150 mm long with papery, clasping, sheathing bases.
Blade - Circular in outline, sometimes notched at the base, 10-50 mm diameter, compound, deeply toothed or lobed often into 3-5 or more egg shaped segments that are also toothed or lobed, hairless to slightly hairy especially on the lower surface. Lower leaves often broader than long and upper leaves longer than broad.
Stem leaves - 25 to 30 mm long. Upper ones may be simple without stalks and grade into deeply lobed and stalked leaves like those at the base. Hairless.

Stems:

100-400 mm long, erect or drooping, branched, solid, stout, fluted in cross section, somewhat succulent and may be hairless or more or less hairy especially towards the top of the stem and around the sheath at the base of the leaf petiole. May form roots at the nodes that are in contact with the soil.

Flower head:

Single flowers at the ends of stems or in leaf axils. Carried on long or short stalks. Each flower forms a globular cluster of 8-20 sharp beaked fruitlets.

Flowers:

Yellow. 8-20 mm across.
Ovary - 8-16 carpels. One ovule per carpel. Short style. Receptacle almost smooth and hairless.
Sepals - 4 or 5 thin and papery, oval to egg shaped, 5-10 mm long, overlapping, slightly rough with a few hairs, and bent back. Fall off early.
Petals - Usually 5, yellow, shiny, oval to egg shaped, 5-10 mm long, slightly longer than the sepals, usually don't overlap. Nectary pouched with and egg shaped lobed.
Stamens - 15-20.
Anthers -

Fruit:

A globular, 10 mm diameter, cluster, of 8-20, sharp pointed achenes. Achenes, pale brown, very flattened, oval to egg shaped, 3-5 mm long x 3-4 mm wide, keeled or angular ridged on the edges, pointed, with spiny, rigid, curved, 'warts' (tubercles) on side faces. Hairless. Top tapers to a broad, flattened, curved beak, about 2 mm long.

Seeds:

Enclosed in fruit (achene).

Roots:

Taproot and roots from nodes where the stems touch the ground.

Key Characters:

Stems leafy.
Leaves alternate or radical, deeply palmately-three-lobed, Few radical leaves or not persistent,
Flower is large and conspicuous 8-20 mm across, regular, not spurred.
Petals are yellow with broad lobes and longer than sepals.
Sepals 4, 6-8 mm long.
Fruiting receptacle short.
Achenes 4-5 x 3-4 mm, sides pale brown with spiny muricate and rough with conspicuous, rigid, curved, tubercles. Achenes in a globular head.
Style of achene becoming a short beak.
Achene beak ca 2 mm long, stout, long, broad.
Large, glabrous annual.
Adapted from J.M. Black, N.T. Burbidge and J.R. Wheeler.

Biology:

Life cycle:

Annual herb. Seeds germinate in autumn and winter. Flowers September to December.

Physiology:

Reproduction:

By seed.

Flowering times:

Spring in western NSW.
September to November in SA.
September to December in Perth.
Spring in WA.

Seed Biology and Germination:

Vegetative Propagules:

Stems root at the nodes.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread mainly by seed.

Origin and History:

Mediterranean and southern Europe.

Distribution:

ACT, NSW, QLD, SA, TAS, VIC, WA.
In all parts of Tasmania.

Courtesy Australia's Virtual Herbarium.

Habitats:

Damp, low-lying, winter wet areas.
Shallow water or regularly flooded areas.

Climate:

Temperate. Mediterranean.

Soil:

Wet soils.

Plant Associations:

Significance:

Beneficial:

Moderately palatable fodder.

Detrimental:

Weed of vegetables, crops, streams, gardens, lawns, wetlands and low lying pastures.
It is principally a weed of disturbed areas but may occur in both arable crops and pastures. It is not found in dry areas but is less restricted to moist situations than Creeping Buttercup (Ranunculus repens). It can be moderately competitive.

Toxicity:

Suspected of being toxic. One reported case of a horse death in NSW.

Symptoms:

Blindness.

Treatment:

Remove stock from infested areas.

Legislation:

None.

Management and Control:

Thresholds:

Eradication strategies:

Prevent seed set.

Herbicide resistance:

Relatively tolerant to glyphosate.

Biological Control:

Related plants:

Australian Buttercup (Ranunculus lappaceus)
Celery Buttercup (Ranunculus sceleratus)
Corn Buttercup (Ranunculus arvensis)
Creeping Buttercup (Ranunculus repens) is very similar in the seedling stage but has hairy leaves. At later stages it has trifoliate or much more deeply lobed leaves with pale veins and creeping, spreading stems. The petals overlap rather than having a space between them.
Large Annual Buttercup (Ranunculus trilobus) has leaves with 3 lobes and flowers that are less than 10 mm diameter.
Pale Hairy Buttercup (Ranunculus sardous)
River Buttercup (Ranunculus inundatus)
Small flowered Buttercup (Ranunculus parviflorus)
Small flowered Buttercup (Ranunculus pumilio)
Small flowered Buttercup (Ranunculus sessiliflorus)
Small River Buttercup (Ranunculus amphitrichus)
Smooth Buttercup (Ranunculus pentandrus)
Snakes tongue Buttercup (Ranunculus ophioglossifolius)
Swamp Buttercup (Ranunculus undosus)

Plants of similar appearance:

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P212. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P363. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P172.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P310-311. Photo.

Gardner, G.A. and Bennetts, H.W. (1956). The toxic plants of Western Australia. (West Australian Newspapers Ltd, Perth). P29.

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). P206-207. Photo.

Hyde-Wyatt, B.H. and Morris, D.I. (1975). Tasmanian weed handbook. (Tasmanian Department of Agriculture, Hobart, Tasmania). P94-95. 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). #1043.5.

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). P66.

McBarron, E.J. (1983). Poisonous plants. (Inkata Press, Melbourne). P53. Diagram.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P141. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.