Aquatic and Wetland Vascular Plants of the Northern Great Plains

Ranunculus L. -- Buttercup, crowfoot

Aquatic, semiaquatic and terrestrial perennials and annuals, some amphibious. Stems erect to procumbent, sometimes floating in water, often rooting at the nodes in some spp., branching or simple. Leaves simple or more often ternately compound to finely dissected, often variable on the same individual in this reguard, alternate or mostly basal or entirely basal; nearly sessile to long-petioled, the petioles often dilated at the base (probably representing stipules), especially in submersed spp. Flowers from terminal buds, sometimes appearing axillary, often showy, borne above the water surface in aquatic spp.; sepals usually 5, greenish, deciduous; petals 5, seldom more, yellow or white, often fading to whitish with age, usually bearing a minute nectary pit covered by a scale toward the base; stamens usually 10-many; pistils usually numerous; receptacle conic to cylindric, glabrous or pubescent. Achenes usually many in a hemispheric, globose or cylindric head; achene body thick or flattened, the coat smooth, ridged, papillate or striate, glabrous or pubescent, tipped with a terminal or lateral style beak.

References:

Benson, L.  1948.  A treatise on the North American ranunculi.  Amer. Midl. 
     Naturalist 40:1-261.

Cook, C. D. K.  1963.  Studies in Ranunculus subgenus Batrachium (DC.) A. Gray 
     II.  General morphological considerations in the taxonomy of the subgenus.  
     Watsonia 5:294-303.

Cook, C. D. K.  1966.  A monographic study of Ranunculus subgenus Batrachium (DC.)
     A. Gray.  Mitt. Bot. Staatssamml. Munchen 6:47-237.

Drew, W. B.  1936.  The North American representatives of Ranunculus sect. Batrachium.
     Rhodora 38:1-47.

Duncan, T.  1980.  A taxonomic study of the Ranunculus hispidus complex in the
     Western Hemisphere.  Univ. of Calif. Bot. Publ. 77:1-125.

Lead	Characteristic	Go To
1	Flowers white; leaves finely divided into filiform segments; plants normally submersed.	Lead 2
1	Flowers yellow; leaves simple to deeply lobed or finely divided into narrow, flat segments; plants submersed or emergent.	Lead 3
2	Achenes (7) 15-25; achene body averaging 1.5 mm long; achene beak prominent, 0.7-1.1 mm long (often shorter when dried).	R. longirostris
2	Achenes 30-45 (80); achene body averaging 1.25 mm or less long; achene beak 0.2-0.5 mm long (often nearly beakless when dried).	R. subrigidus
3	Leaves all simple and entire or crenate to crenate-lobed.	Lead 4
3	All, or at least the cauline leaves deeply lobed, divided or compound.	Lead 5
4	Leaves ovate to round or reniform, crenate to crenate-lobed; achenes striate with longitudinal ribs.	R. cymbalaria
4	Leaves elliptic to lanceolate or linear, entire to denticulate; achenes not striate.	R. flammula
5	Basal and cauline leaves distinctly different in shape, the basal leaves mostly entire or crenate, not lobed or divided, the cauline leaves deeply divided.	R. cardiophyllus
5	Basal and cauline leaves essentially similar in shape and form, all variously lobed, deeply divided or compound, none merely crenate.	Lead 6
6	Achenes turgid, without a sharp border.	Lead 7
6	Achenes flattened, with a sharp or winglike border.	Lead 9
7	Petals 4-14 mm long; achenes 1.2-2.5 mm long, beaked; plants aquatic or amphibious perennials.	Lead 8
7	Petals 3-5 mm long; achenes 0.8-1.2 mm long, nearly beakless; plants weedy annuals, usually emersed.	R. sceleratus
8	Achene margin thickened and corky below the middle; petals mostly 6-14 mm long.	R. flabellaris
8	Achene margin rounded but not thickened, petals mostly 4-8 mm long.	R. gmelinii
9	Petals 2-5 mm long; anthers less than 1 mm long; stems not rooting at the nodes.	Lead 10
9	Petals 7-16 mm long; anthers longer than 1 mm; stems often recurved and rooting at the nodes.	R. hispidus
10	Petals distinctly shorter than the sepals; heads of achenes ovoid-cylindric to cylindric.	R. pensylvanicus
10	Petals equaling or longer than the sepals; heads of the achenes ovoid to globose.	R. macounii

9. Ranunculaceae, the Buttercup Family

4. Ranunculus L. -- Buttercup, crowfoot

1. Ranunculus cardiophyllus Hook.

2. Ranunculus cymbalaria Pursh -- Seaside buttercup

3. Ranunculus flabellaris Raf. -- Yellow water-crowfoot

4. Ranunculus flammula L. -- Spearwort

5. Ranunculus gmelinii DC. -- Yellow water-crowfoot

6. Ranunculus hispidus Michx. -- Marsh buttercup

7. Ranunculus longirostris Godr. -- White water-crowfoot

8. Ranunculus macounii Britt. -- Macoun's buttercup

9. Ranunculus pensylvanicus L. f. -- Bristly crowfoot

10. Ranunculus sceleratus L. -- Cursed crowfoot

11. Ranunculus subrigidus W.B. Drew -- White water-crowfoot

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