Ranunculus tripartitus

Tracheophyta MagnoliopsidaRanunculaceaeRanunculusRanunculus tripartitus

Ecology

An annual of shallow water bodies over base- and nutrient-poor substrates, in open sites which are flooded in winter but summer-dry. In S.E. England it is also found in pools in coppiced woodland. Lowland to 300 m at Belstone (N. Devon).

Status

Native

World Distribution

Oceanic Southern-temperate element.

© K.J. Walker, BSBI

Broad Habitats

Standing water and canals

Light (Ellenberg): 9

Moisture (Ellenberg): 10

Reaction (Ellenberg): 6

Nitrogen (Ellenberg): 3

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 5.2

July Mean Temperature (Celsius): 15.8

Annual Precipitation (mm): 1024

Height (cm): 9

Length: 25

Perennation - primary

Annual

Perennation - secondary

Perennial

Life Form - primary

Annual hydrophyte (aquatic therophyte)

Comment on Life Form

Normally an annual under field conditions (P & C 1994)

Woodiness

Herbaceous

Clonality - primary

Little or no vegetative spread

Count of 10km squares in Great Britain: 79

Count of 10km squares in Ireland: 1

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -1.09

Plantatt Conservation Status

Vulnerable

JNCC Designations

NBNSYS0000002724

Scarce Atlas Account

Scarce Atlas Account: 

Ranunculus tripartitus DC.

Three-lobed crowfoot

Status: scarce

 

R. tripartitus occurs in shallow but seasonal bodies of water among heaths or related communities, especially shallow ditches and ponds, cart-tracks and gate-ways, wet in winter and spring but dry by summer. The soil base-status and pH are moderately high. Associates include Apium inundatum, Cicendia filiformis, Eleogiton fluitans, Juncus pygmaeus (Lizard Peninsula only), Lythrum portula, Pilularia globulifera, Potamogeton polygonifolius and a variety of charophytes. Like other pond and trackway species of heaths and commons, R. tripartitus is intolerant of competition from other plant species, needing open sites maintained by fluctuating water levels, grazing and poaching by livestock, and disturbance by traffic.

Typically a winter annual, germinating in autumn and flowering in April and May, earlier than related species. Its sites often dry out completely by June.

R. tripartitus may be under-recorded, partly because of its early flowering, partly from problems of identification. Typical R. tripartitus is very local and diminishing through the destruction of heaths, draining or infilling of its habitats, and the cessation of grazing and disturbance which allow development of Salix aurita and S. cinerea. The long viability of its seed allows it to recover if overgrown sites are cleared, provided drainage has not been too severe. The Lizard Peninsula is the only area in Britain where R. tripartitus is at all frequent. Plants recorded as R. lutarius auct. in the New Forest are actually a pentaploid hybrid between R. omiophyllus and R. tripartitus (R. x novae-forestae); the presence of pure R. tripartitus in the New Forest has not been confirmed although some of these hybrids are very similar to it (Cook 1966; Webster 1990). 

R. tripartitus is very local globally, occurring in north-western Europe from south-west Spain to northern Germany, and is also reported from Greece and Morocco (Jalas & Suominen 1989). It is declining throughout the northern part of its range.

 

A. J. Byfield