Ranunculus aquatilis var. diffusus


Arr. Brit. Pl. ed. 3, 2: 507. 1796.

Synonyms: Batrachium circinatum subsp. subrigidum (W. B. Drew) A. Löve & D. Löve Batrachium flaccidum (Persoon) Ruprecht Batrachium longirostris (Godron) F. W. Schultz Batrachium trichophyllum (Chaix) Bosch Batrachium trichophyllum subsp. lutulentum (Perrier & Songeon) Janchen ex V. V. Petrovsky Ranunculus aquatilis var. calvescens (W. B. Drew) L. D. Benson Ranunculus aquatilis var. capillaceus (Thuillier) de Candolle Ranunculus aquatilis var. eradicatus Laestadius Ranunculus aquatilis var. harrisii L. D. Benson Ranunculus aquatilis var. longirostris (Godron) Lawson Ranunculus aquatilis var. porteri (Britton) L. D. Benson Ranunculus aquatilis var. subrigidus (W. B. Drew) Breitung Ranunculus circinatus var. subrigidus (W. B. Drew) L. D. Benson Ranunculus confervoides Ranunculus longirostris Ranunculus subrigidus Ranunculus trichophyllus Ranunculus trichophyllus var. calvescens W. B. Drew Ranunculus trichophllus var. eradicatus (Laestadius) W. B. Drew Ranunculus trichophyllus subsp. lutulentus (Perrier & Songeon) Vierhapper
Treatment appears in FNA Volume 3.

Leaves all filiform-dissected. Achenes 1-1.8 × 0.8-1.2 mm; beak 0.2-1.2 mm. 2n = 16, 32, 48.

Phenology: Flowering spring–summer (Apr–Sep).
Habitat: Ponds, lakes, streams, ditches, edges of rivers
Elevation: 0-3200 m


V3 44-distribution-map.gif

Greenland, Alta., B.C., Man., N.B., Nfld. and Labr. (Nfld.), N.W.T., N.S., Nunavut, Ont., P.E.I., Que., Sask., Yukon, Ala., Alaska, Ariz., Ark., Calif., Colo., Conn., Del., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.Mex., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Mexico, Eurasia, Australia.


Populations of Ranunculus aquatilis var. diffusus with long achene beaks are not known from the Old World. In North America, beak length varies continuously over the whole range given for the variety, and separation of plants with unusually long beaks as R. longirostris is not tenable. Ranunculus aquatilis var. diffusus shows geographic variation, and some regional forms have been recognized as separate varieties. Dwarf creeping arctic plants may be called R. aquatilis var. eradicatum, plants with sparsely pubescent or glabrous receptacle from eastern North America may be called R. aquatilis var. calvescens, plants with linear, noncapillary leaf segments from the northern Great Basin may be called R. aquatilis var. porteri, and very robust plants from Oregon and northernmost California may be called R. aquatilis var. harrisii. Extreme forms of these races are recognizable, but they intergrade and many specimens cannot be confidently assigned to one or another of them.

The Eurasian species Ranunculus circinatus Sibthorp has been reported from North America. These reports are based on specimens of R. aquatilis var. diffusus.

Selected References


Lower Taxa

Alan T. Whittemore +
Withering +
Ranunculus sect. Batrachium +
Greenland +, Alta. +, B.C. +, Man. +, N.B. +, Nfld. and Labr. (Nfld.) +, N.W.T. +, N.S. +, Nunavut +, Ont. +, P.E.I. +, Que. +, Sask. +, Yukon +, Ala. +, Alaska +, Ariz. +, Ark. +, Calif. +, Colo. +, Conn. +, Del. +, Idaho +, Ill. +, Ind. +, Iowa +, Kans. +, Ky. +, Maine +, Md. +, Mass. +, Mich. +, Minn. +, Mo. +, Mont. +, Nebr. +, Nev. +, N.H. +, N.Mex. +, N.J. +, N.Y. +, N.C. +, N.Dak. +, Ohio +, Okla. +, Oreg. +, Pa. +, R.I. +, S.C. +, S.Dak. +, Tenn. +, Tex. +, Utah +, Vt. +, Va. +, Wash. +, W.Va. +, Wis. +, Wyo. +, Mexico +, Eurasia +  and Australia. +
0-3200 m +
Ponds, lakes, streams, ditches, edges of rivers +
Flowering spring–summer (Apr–Sep). +
Arr. Brit. Pl. ed. +
Batrachium circinatum subsp. subrigidum +, Batrachium flaccidum +, Batrachium longirostris +, Batrachium trichophyllum +, Batrachium trichophyllum subsp. lutulentum +, Ranunculus aquatilis var. calvescens +, Ranunculus aquatilis var. capillaceus +, Ranunculus aquatilis var. eradicatus +, Ranunculus aquatilis var. harrisii +, Ranunculus aquatilis var. longirostris +, Ranunculus aquatilis var. porteri +, Ranunculus aquatilis var. subrigidus +, Ranunculus circinatus var. subrigidus +, Ranunculus confervoides +, Ranunculus longirostris +, Ranunculus subrigidus +, Ranunculus trichophyllus +, Ranunculus trichophyllus var. calvescens +, Ranunculus trichophllus var. eradicatus +  and Ranunculus trichophyllus subsp. lutulentus +
Ranunculus aquatilis var. diffusus +
Ranunculus aquatilis +
variety +