Ranunculus orthorhynchus
Ranunculus auricomus
Bloomer's buttercup, straight-beak buttercup, swamp buttercup
Greenland buttercup
sometimes fleshy and ± tuberous.
filiform, 0.2-0.6 mm thick.
nearly erect or decumbent, never rooting nodally, hispid, strigose, or glabrous, base not bulbous.
erect or ascending, 12-30 cm, glabrous, each with 1-4 flowers.
blades narrowly ovate to oblong or semicircular in outline, simple to 3-5-lobed or -foliolate, 2.8-12.5 × 2.5-14 cm, leaflets or segments undivided or 1-2x-lobed or -parted, ultimate segments circular to linear, margins dentate, crenate, or entire, apex rounded to narrowly acute.
persistent, blades reniform, 3-parted, 1.2-2.8 × 1.6-4.6 cm, segments again lobed or parted, base cordate, margins toothed, apices of segments rounded in outline.
receptacle hispid;
sepals reflexed 1-2 mm above base, 5-11 × 2-4 mm, hispid, hirsute, or glabrous;
petals 5-6, abaxially yellow or red, adaxially yellow, 8-18 × 4-11 mm.
pedicels appressed-pubescent;
receptacle finely canescent;
sepals 4-7 × 2.5-4 mm, abaxially sparsely pilose, hairs colorless;
petals 5, 6-10(-15) × 5-9 mm;
nectary scale glabrous.
hemispheric to ovoid, 5-13 × 6-10 mm;
achenes 2.8-4.5 × 1.8-3.2 mm, glabrous, margin forming narrow rib 0.1-0.2 mm wide;
beak persistent, narrowly lanceolate to subulate, straight, 1.8-3.8(-4.8) mm.
globose to short-ovoid, 5-8 × 5-6 mm;
achenes 2-2.2 × 1.8-2 mm, glabrous or sparsely and finely canescent distally;
beak lanceolate, weakly to strongly curved, 1.2-2 mm.
= 16.
Ranunculus orthorhynchus
Ranunculus auricomus
Varieties 3
The first two varieties (Ranunculus orthorhynchus var. orthorhynchus and R. orthorhynchus var. platyphyllus) are rather weak, intergrading extensively in California and Oregon. By contrast, R. orthorhynchus var. bloomeri often grows with the others with little or no intergradation (although intermediate populations are found in some areas), and it has been treated as a distinct species, R. bloomeri, by many taxonomists.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Ranunculus auricomus is predominantly apomictic, with irregular meiosis. Different European races may show a variety of characteristics not found in Greenland material (pilose stems, undivided, crenate-dentate leaves, densely canescent achenes, and glabrous receptacles). T. W. Böcher et al. (1968) recognized three distinct races from Greenland, distinguished by minor differences in stature and branching of the plants, width of cauline leaf segments, and indument of achenes. Those races, which were evidently based on very few collections, were named as subspecies by L. Fagerström and G. Kvist (1983). More ample material collected during the 1980s does not support the Fagerström and Kvist classification. Except for stature and branching, which both depend on the general vigor of the plants, these characteristics are poorly correlated with one another and with geographic place of collection. Cauline leaf segments sometimes vary in width within a single collection, and achenes of the Ymer Island collection that they referred to R. auricomus subsp. glabratus are sparsely canescent, not glabrous as stated. These observations, together with the uniformity of indument, leaf shape, and receptacle and achene morphology in the Greenland populations, suggest that they are best considered a single race within the variable apomictic complex comprising R. auricomus in the broad sense.
T. G. Tutin and J. R. Akeroyd (1993) treated Ranunculus auricomus var. glabratus as a synonym of R. affinis (= R. pedatifidus var. affinis; see above). The characteristics in that key and description (leaves palmately 3-5-lobed, achenes in globose heads) do not match American material of R. pedatifidus var. affinis.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Basal leaves simple or 3-foliolate, if compound then leaflets undivided, margins crenate; petals retuse. | var. bloomeri |
1. Basal leaves 3–5-foliolate, leaflets lobed or parted, margins entire or dentate; petals truncate or rounded. | → 2 |
2. Heads of achenes hemispheric or sometimes globose, 5–7 mm; petals often abaxially red. | var. orthorhynchus |
2. Heads of achenes globose or ovoid, 8–13 mm; petals yellow. | var. platyphyllus |
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WA - Local Web sites: CalFlora, CalPhotos,
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PNW Herbaria, Turner Photog. 
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