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low buttercup, low spearwort, weak buttercup

water-plantain crowfoot, waterplantain spearwort

Roots

not thickened basally, glabrous.

not thickened basally, glabrous or somewhat canescent proximally.

Stems

erect or ascending, rooting at most proximal nodes, glabrous.

erect or ascending, rooting at proximal nodes, glabrous or sparsely hirsute.

Proximal cauline leaf blades

ovate or lanceolate, 1.2-4.2 × 0.5-1.2 cm, base acute to truncate, margins entire or denticulate, apex acuminate to rounded.

lanceolate, 5.9-12.2 × 1.1-2.4 cm, base rounded-obtuse to acuminate, margins denticulate, apex acuminate.

Inflorescences

bracts linear to lanceolate or oblanceolate.

bracts linear or lanceolate.

Flowers

receptacle glabrous;

sepals 4-5, spreading or reflexed from base, 1.5-3 × 1-1.5 mm, glabrous or sparsely hirsute;

petals 1-3, 1.5-2 × 0.5-1 mm;

nectary scales glabrous.

receptacle glabrous;

sepals 5, spreading or sometimes reflexed from base, 3-5 × 2-3 mm, glabrous;

petals 5, 5-8 × 2-3 mm;

nectary scales glabrous.

Heads of achenes

hemispheric to cylindric, 2-8 × 2-3 mm;

achenes 1-1.2 × 0.6-0.8 mm, ± tuberculate, glabrous;

beak absent or nearly so, to 0.1 mm.

short-ovoid to depressed-globose, 5-7 × 4-8 mm;

achenes 1.8 × 1.2-1.4 mm, glabrous;

beak lanceolate, straight, 0.6-1.2 mm.

Ranunculus pusillus

Ranunculus ambigens

Phenology Flowering spring (Apr–Jun). Flowering late spring–summer (May–Aug).
Habitat Ditches, ponds, and swamps Creeks, ponds, ditches, marshes
Elevation 0-300 m (0-1000 ft) 0-700 m (0-2300 ft)
Distribution
from FNA
AL; AR; CA; DC; DE; FL; GA; IL; IN; KY; LA; MD; MO; MS; NC; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; CT; DC; DE; GA; IL; IN; KY; LA; MA; MD; ME; MI; NC; NH; NJ; NY; OH; PA; RI; TN; VA; WV
[WildflowerSearch map]
[BONAP county map]
Discussion

In most specimens of Ranunculus pusillus, the heads of achenes are hemispheric to short-ovate and only 2-3 mm. Occasional plants with cylindric heads of achenes 4-6 mm from the Gulf Coast states have been called R. pusillus var. angustifolius.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

The name Ranunculus obtusiusculus Rafinesque has been mistakenly used for R. ambigens.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 3. FNA vol. 3.
Parent taxa Ranunculaceae > Ranunculus > subg. Ranunculus > sect. Flammula Ranunculaceae > Ranunculus > subg. Ranunculus > sect. Flammula
Sibling taxa
R. abortivus, R. acriformis, R. acris, R. adoneus, R. alismifolius, R. allegheniensis, R. allenii, R. ambigens, R. andersonii, R. aquatilis, R. arizonicus, R. arvensis, R. auricomus, R. austro-oreganus, R. bonariensis, R. bulbosus, R. californicus, R. canus, R. cardiophyllus, R. cooleyae, R. cymbalaria, R. eschscholtzii, R. fascicularis, R. fasciculatus, R. ficaria, R. flabellaris, R. flammula, R. gelidus, R. glaberrimus, R. glacialis, R. gmelinii, R. gormanii, R. harveyi, R. hebecarpus, R. hederaceus, R. hispidus, R. hydrocharoides, R. hyperboreus, R. hystriculus, R. inamoenus, R. jovis, R. kamtschaticus, R. lapponicus, R. laxicaulis, R. lobbii, R. macauleyi, R. macounii, R. macranthus, R. marginatus, R. micranthus, R. muricatus, R. nivalis, R. occidentalis, R. oresterus, R. orthorhynchus, R. pacificus, R. pallasii, R. parviflorus, R. pedatifidus, R. pensylvanicus, R. platensis, R. populago, R. pygmaeus, R. ranunculinus, R. recurvatus, R. repens, R. rhomboideus, R. sabinei, R. sardous, R. sceleratus, R. sulphureus, R. testiculatus, R. trilobus, R. triternatus, R. turneri, R. uncinatus
R. abortivus, R. acriformis, R. acris, R. adoneus, R. alismifolius, R. allegheniensis, R. allenii, R. andersonii, R. aquatilis, R. arizonicus, R. arvensis, R. auricomus, R. austro-oreganus, R. bonariensis, R. bulbosus, R. californicus, R. canus, R. cardiophyllus, R. cooleyae, R. cymbalaria, R. eschscholtzii, R. fascicularis, R. fasciculatus, R. ficaria, R. flabellaris, R. flammula, R. gelidus, R. glaberrimus, R. glacialis, R. gmelinii, R. gormanii, R. harveyi, R. hebecarpus, R. hederaceus, R. hispidus, R. hydrocharoides, R. hyperboreus, R. hystriculus, R. inamoenus, R. jovis, R. kamtschaticus, R. lapponicus, R. laxicaulis, R. lobbii, R. macauleyi, R. macounii, R. macranthus, R. marginatus, R. micranthus, R. muricatus, R. nivalis, R. occidentalis, R. oresterus, R. orthorhynchus, R. pacificus, R. pallasii, R. parviflorus, R. pedatifidus, R. pensylvanicus, R. platensis, R. populago, R. pusillus, R. pygmaeus, R. ranunculinus, R. recurvatus, R. repens, R. rhomboideus, R. sabinei, R. sardous, R. sceleratus, R. sulphureus, R. testiculatus, R. trilobus, R. triternatus, R. turneri, R. uncinatus
Synonyms R. oblongifolius, R. pusillus var. angustifolius, R. tener
Name authority Poiret: in J. Lamarck et al., Encycl. 6: 99. (1804) S. Watson: Bibl. Index N. Amer. Bot. 1: 16. (1878)
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