Ranunculus sect. Flammula
Ranunculus ambigens
creeping buttercup, creeping crowfoot, creeping spearwort, greater creeping spearwort, lesser spearwort, lesser water buttercup, spearwort
water-plantain crowfoot, waterplantain spearwort
basal and sometimes also nodal, sometimes tuberous-thickened proximally.
not thickened basally, glabrous or somewhat canescent proximally.
erect to decumbent or prostrate, not bulbous-based, without bulbils.
erect or ascending, rooting at proximal nodes, glabrous or sparsely hirsute.
basal and cauline or all cauline;
basal leaves when present similar to proximal cauline leaves;
proximal cauline leaves petiolate, blades undivided, margins entire or finely toothed;
distal cauline leaves simple, unlobed.
lanceolate, 5.9-12.2 × 1.1-2.4 cm, base rounded-obtuse to acuminate, margins denticulate, apex acuminate.
1-15(-40)-flowered cymes.
bracts linear or lanceolate.
pedicellate;
sepals deciduous soon after anthesis, 3-5;
petals yellow;
nectary scale attached on 3 sides, forming pocket enclosing nectary, or sometimes projecting as free flap shorter than pocket, glabrous or ciliate, free margin entire or lobed;
style present.
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.
achenes, 1-locular;
achene body globose-lenticular to globose, 1-2 times as wide as thick, not prolonged beyond seed;
achene wall thick, smooth, not ornamented (sometimes pubescent);
margins low narrow ridge;
beak much shorter than achene body.
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 sect. Flammula
Ranunculus ambigens
Species ca. 25 (10 in the flora).
The species of Ranunculus sect. Flammula are distinctive and easily recognized. Like many amphibious plants, however, they are very variable morphologically, and the species are difficult to define. The taxonomic status of the local endemic species recognized below should be reinvestigated. Depauperate plants of R. glaberrimus (R. sect. Epirotes) may have few or none of the leaves lobed. Such plants were formerly treated under the name R. oreogenes and referred to R. sect. Flammula. In the treatment of R. sect. Flammula below they will key to R. alismifolius var. alismellus, from which they differ in their usually ciliate nectary scales, larger sepals and petals, and larger heads of achenes.
The name Ranunculus lindheimeri Engelmann has been applied to specimens belonging to this section. The name has never been validly published, and its correct application is unclear.
(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.)
1. Petals 1-3, 1.5-2.5 mm. | → 2 |
1. Petals 4-12, 2-14 mm. | → 3 |
2. Bracts elliptic to ovate; achenes 1.4-1.8 mm; sepals 3. | R. bonariensis var. trisepalus |
2. Bracts linear to lanceolate or oblanceolate; achenes 1-1.2 mm; sepals 4-5. | R. pusillus |
3. Bases of roots conspicuously fusiform-thickened. | → 4 |
3. Bases of roots not thickened. | → 6 |
4. Stems prostrate, sometimes rooting nodally. | R. gormanii |
4. Stems erect or ascending, not rooting nodally. | → 5 |
5. Bases of basal leaf blades acute. | R. alismifolius |
5. Bases of basal leaf blades broadly obtuse to cordate. | R. populago |
6. Achenes 0.8-1 mm; se United States. | R. laxicaulis |
6. Achenes 1.2-2.8 mm; widespread. | → 7 |
7. Stems erect or ascending, not rooting nodally. | → 8 |
7. Stems erect or ascending to prostrate, rooting nodally. | → 9 |
8. Roots canescent; petals 4-6 mm. | R. oresterus |
8. Roots glabrous; petals 5-14 mm. | R. alismifolius |
9. Blades of well-developed leaves 5.9-12.2× 1.1-2.4 cm, acuminate at apex. | R. ambigens |
9. Blades of well-developed leaves not as above, either 0.8-1.9(-2.7) cm long or 0.04-1 cm wide; acute or rounded to filiform at apex. | → 10 |
10. Leaf blades lanceolate to oblanceolate or filiform, base acute to filiform; beak of achene 0.1-0.6 mm; widespread. | R. flammula |
10. Leaf blades ovate to broadly ovate, base rounded to weakly cordate; beak of achene 0.4-1 mm; desert southwest. | R. hydrocharoides |
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