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Ranunculus austro-oreganus

southern Oregon buttercup

arctic buttercup, far-northern buttercup, high northern buttercup, renoncule hyperboréale

Roots

never tuberous.

Stems

erect or ascending, never rooting nodally, crisped-pilose, base not bulbous.

prostrate, glabrous, rooting nodally.

Leaves

basal leaves absent, cauline leaf blades reniform to broadly flabellate, deeply 3-lobed or 3-parted, 0.3-1.2 × 0.5-2.1 cm, base obtuse to cordate, lobes undivided or lateral lobes cleft, terminal segment entire or distally crenulate, apex rounded.

Basal leaf blades

broadly rhombic to semicircular in outline, 3-parted, 2.8-4.3 × 3-5.5 cm, segments 3-lobed, ultimate segments lanceolate, margins entire or toothed, apex narrowly acute or acuminate.

Flowers

receptacle glabrous;

sepals reflexed 1 mm above base, 4-6 × 1.5-3 mm, densely pilose;

petals 5, abaxially red, adaxially yellow, 10-12 × 4-6 mm.

receptacle glabrous;

sepals 3-4, spreading or reflexed from base, 2-4 × 1-3 mm, glabrous;

petals 3-4, 2-4 × 1-3 mm;

nectary on petal surface, scale poorly developed and forming crescent-shaped ridge surrounding but not covering nectary;

style 0.1-0.2 mm.

Heads

of achenes hemispheric, 4-7 × 7-10 mm;

achenes 3.4-4.2 × 2.8-3.2 mm, sometimes basally pilose, margin forming narrow rib 0.1-0.2 mm wide;

beak persistent, lance-subulate, straight or somewhat curved distally, 1.6-2.6 mm.

of achenes globose or short-ovoid, 3-5 × 2-5 mm;

achenes 1-1.4 × 0.8-1.2 mm, glabrous;

beak linear, curved, 0.1-0.4 mm.

2n

= 32.

Ranunculus austro-oreganus

Ranunculus hyperboreus

Phenology Flowering spring (May). Flowering late spring–summer (Jun–Aug).
Habitat Grassy hillsides Floating in shallow water or stranded on exposed mud at margins of streams and ponds and open wet soil and marshes, in tundra or boreal or subalpine forest
Elevation 500 m [1600 ft] 0-3400 m [0-11200 ft]
Distribution
from FNA
OR
[WildflowerSearch map]
from FNA
AK; CO; ID; MT; NV; UT; WY; AB; BC; MB; NF; NT; ON; QC; SK; YT; Greenland; Eurasia
[WildflowerSearch map]
[BONAP county map]
Discussion

Of conservation concern.

Ranunculus austro-oreganus is doubtfully distinct from R. occidentalis var. howellii. L. D. Benson (1954) described the stem as bulbous-based and similar to that of R. bulbosus, but a differentiated base is not evident in material I have seen (some of which was cited by Benson).

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

Specimens of Ranunculus hyperboreus from the central and southern Rocky Mountains have the leaves always cordate and the fruiting heads always 4-5 mm; they have been separated as R. hyperboreus subsp. intertextus. Although Arctic specimens are more variable, they often have shallowly cordate leaf bases and equally large heads of achenes, so segregation of the subspecies seems inappropriate.

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

Parent taxa Ranunculaceae > Ranunculus > subg. Ranunculus > sect. Ranunculus Ranunculaceae > Ranunculus > subg. Ranunculus > sect. Hecatonia
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. 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
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. 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. hyperboreus subsp. arnellii, R. hyperboreus subsp. intertextus, R. hyperboreus var. samojedorum, R. hyperboreus var. tricrenatus, R. hyperboreus var. turquetilianus, R. natans var. intertextus
Name authority L. D. Benson: Amer. Midl. Naturalist 52: 341. (1954) Rottbøll: Skr. Kiøbenhavnske Selsk. Laerd. Elsk. 10: 458. (1770)
Source FNA vol. 3. Treatment author: Alan T. Whittemore. FNA vol. 3. Treatment author: Alan T. Whittemore.
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