1	"Submerged aquatic with leaves divided into numerous filiform segments, the segments not arranged within a single plane; petals white; achenes transversely ridged"	"Ranunculus trichophyllus"
1	"Terrestrial herbs, or, if aquatic and with divided leaves, the segments broader and arranged in 1 plane; petals usually yellow; achenes various, but not transversely ridged"	2
2	"Plants perennial, but leaves often winter-deciduous, resprouting from a persistent rootstock; achenes smooth or ridged but not conspicuously tuberculate"	3
2	"Plants annual; achenes often tuberculate"	27
3	"Plants with rhizomes or stolons; petals often oblong or narrowly obovate"	4
3	"Plants tufted, sometimes with slightly tuberiform roots; petals usually obovate to broadly obovate"	16
4	"Leaves pinnately divided into rather distant linear, subterete segments; deeply rhizomic herb of higher alps, flowers large, appearing soon after snow-melt"	"Ranunculus gunnianus"
4	"Leaves entire or variously lobed to pinnatisect, segments usually flat"	5
5	"Petals relatively large, 5–10 mm wide; nectary lobe broadly cuneate; vigorous weeds"	6
5	"Petals less than 5 mm wide"	7
6	"Leaves glabrous to pilose, often slightly variegated; pedicels grooved; receptacle pubescent; common weed of ditches and moist roadsides, usually spreading by above-ground stolons"	"Ranunculus repens"
6	"Leaves rather densely pubescent (at least beneath), not variegated; pedicels terete; receptacle glabrous; plants with coarse subterranean rhizomes"	"Ranunculus acris"
7	"Nectary lacking a lobe, appearing as a crescentic bracket"	8
7	"Nectary with a distinct lobe, often the lateral margins partly or wholly fused to the petal and forming a narrow pocket"	10
8	"Leaves simple"	"Ranunculus flammula"
8	"Leaves dissected"	9
9	"Leaves pinnatisect; flower usually white; confined to shallow pools in alps"	"Ranunculus millanii"
9	"Leaves trilobed to palmately divided; flower pale yellow; widespread"	"Ranunculus amphitrichus"
10	"All leaves trilobed with more or less cuneate segments, these sometimes toothed or shallowly lobed"	"Ranunculus collinus"
10	"Adult leaves palmately lobed or trilobed, with oblong to linear segments"	11
11	"Petals c. 3–5 mm long; flowering stems commonly c. 5 cm high or less"	"Ranunculus diminutus"
11	"Petals 5.5–12 mm long; flowering stems commonly 10 cm high or more"	12
12	"Mature achene with lateral ridges; free part of nectary lobe truncate or emarginate"	13
12	"Mature achene not obviously ridged on sides, often with a broad dorsal thickening; free part of nectary lobe obtuse"	14
13	"Achenes usually more than 20 per head, each c. 2 mm long, with c. 6 narrow ridges on the sides; plants typically at least 30 cm high"	"Ranunculus undosus"
13	"Achenes fewer than 20 per head, each 2.5–3 mm long, with 2 or 3 rather broad ridges on the sides; plants rarely taller than c. 20 cm"	"Ranunculus glabrifolius"
14	"Leaf-segments 2 mm wide or wider; sepals hispid; usually on seasonally wet ground but not submerged"	"Ranunculus papulentus"
14	"Leaf-segments slender, linear, c. 1mm wide; sepals glabrous or very sparsely pilose; plants often (at least partially) submerged"	15
15	"Leaf lamina 5–13 cm diam.; petals 8–16, 5–13 mm long; achenes 2–4 mm long (excluding beak)"	"Ranunculus amplus"
15	"Leaf lamina 1–3.5(–5) cm diam.; petals 5–7, 4.5–7 mm long; achenes 1.5–1.8 mm long (excluding beak)"	"Ranunculus inundatus"
16	"Leaves pinnate or pinnatisect; alpine plants"	17
16	"Leaves entire or ternately lobed or divided; alpine or lowland plants"	19
17	"Leaf-segments relatively broad, never linear"	"Ranunculus pimpinellifolius"
17	"Leaf-segments oblong to terete"	18
18	"Leaf-segments terete or semi-terete; flowers large (20 mm diam. or more), bright yellow, appearing soon after snow-melt"	"Ranunculus gunnianus"
18	"Leaf-segments linear but more or less flat; flowers usually white, less than 20 mm diam.; plants typically of shallow pools or depressions"	"Ranunculus millanii"
19	"Sepals reflexed at anthesis; achenes sometimes with a row of stiff appressed hairs along the dorsal margin"	20
19	"Sepals spreading at anthesis; achenes glabrous"	21
20	"Achene beak less than 1 mm long, strongly recurved"	"Ranunculus plebeius"
20	"Achene beak 1.2 mm long or more, straight or arching with a recoiled tip"	"Ranunculus scapiger"
21	"Achenes very plump, virtually flat dorsally; roots often somewhat tuberous"	"Ranunculus pachycarpus"
21	"Achenes more or less lenticular, acute or obtusely angled dorsally"	22
22	"Nectary lobe cuneate or obovate, more or less truncate, widest at the apex; flowers usually 2–several on branched stems; roots fibrous or fleshy-tuberous; lowlands to subalps"	23
22	"Nectary lobe oblong to obovate, widest near the middle; flowers solitary on unbranched stems (rarely with 2–3 flowers in R. graniticola); roots fibrous; subalpine to alpine"	24
23	"Achene biconvex, obovate, smooth on sides; beak slender; widespread, mostly in forested areas, common in east"	"Ranunculus lappaceus"
23	"Achene flattish with thickened margin, rather angular, often wider than long and ridged on sides; beak rather stout; inhabiting swamps and depressions in west"	"Ranunculus robertsonii"
24	"Hairs on stems and petioles spreading"	"Ranunculus graniticola"
24	"Hairs on stems and petioles appressed"	25
25	"Leaves ovate to spathulate, entire or shortly and broadly 3-toothed at apex; upper surface with numerous rigid semi-appressed to spreading hairs; petioles to c. 10 cm long (often much less); nectary lobe minute or absent"	"Ranunculus muelleri"
25	"Leaves shallowly to deeply 3-toothed, or ternately or biternately lobed, upper surface with scattered short appressed hairs; petioles commonly longer than 10 cm; nectary lobe oblong to obovate"	26
26	"Leaves shallowly to deeply 3-toothed or lobed with segments usually directed forwards, entire, toothed or again 3-lobed; ultimate segments lanceolate or broad-lanceolate"	"Ranunculus victoriensis"
26	"Leaves ternate with segments widely spreading, ternately or biternately lobed; ultimate segments linear-lanceolate"	"Ranunculus eichlerianus"
27	"Leaves simple throughout, narrow-elliptic"	"Ranunculus ophioglossifolius"
27	"At least the lower leaves toothed or lobed to some degree"	28
28	"Fruiting head more or less cylindric; achenes plump, without coarse bristles or tubercles, 70-100 or more per head"	"Ranunculus sceleratus"
28	"Fruiting head more or less globoid; achenes strongly flattened, usually with bristles or tubercles, fewer than 50 per head"	29
29	"Flowers 5 mm diam. or more, petals conspicuous; receptacle hairy"	30
29	"Flowers less than 5 mm diam., petals inconspicuous; receptacle glabrous"	32
30	"Mature achene 7 mm long or more; at least the basal leaves crenate to shallowly lobed"	"Ranunculus muricatus"
30	"Mature achene (including beak) 2–3 mm long; leaves deeply lobed"	31
31	"Achenes entirely smooth or with scattered, low obtuse tubercles toward the margin"	"Ranunculus sardous"
31	"Achenes evenly covered with short acute tubercles"	"Ranunculus trilobus"
32	"Achenes orbicular, very thin and often twisted at maturity; tubercles largely confined to central part of achene faces"	"Ranunculus pentandrus"
32	"Achenes ovate, strongly or weakly biconvex, but not twisting at maturity; tubercles evenly distributed or achene faces smooth"	33
33	"Achenes (including beak) 2.5 mm long or more; petals shortly exceeding sepals; nectary attached about one-third of petal length from base; at least the lower leaves almost circular in outline and shallowly lobed"	"Ranunculus parviflorus"
33	"Achenes (including beak) barely 2 mm long; petals shorter than sepals; nectary attached about half petal length from base; leaves usually deeply divided"	34
34	"Achenes lenticular, either smooth and glabrous, or largely covered with appressed hairs, each longer than the diameter of its subtending tubercle; beak of achene usually less than 25% total length of achene"	"Ranunculus pumilio"
34	"Achenes flattish, with scattered tubercles having short hooked bristles that are no longer than the diameter of the tubercle; beak of achene usually 30–50% total length of achene"	"Ranunculus sessiliflorus"