R. D. Meikle, Flora of Cyprus 1. 1977
but supplemented and names used differing
1Aquatic herbs with stipulate, finely dissected submerged leaves; petals white or yellow only at the base; carpels transversely wrinkled
1'Terrestrial herbs; leaves exstipulate; petals usually yellow or sometimes coloured; achenes not transversely wrinkled
2Floating leaves absent; flowers usually large; peduncles generally much longer than leaves, seldom recurved
2'Floating leaves present, divided into 3-5 bluntly lobed segments; flowers rather small; peduncles often shorter than floating leaves, usually recurved
3Leaves all undivided, entire, with dentate or subentire margins
3'All or some of the leaves compound or deeply lobed
4Flowers very large, 2.5-7 cm diam.; petals often red, pink or white; anthers violet-purple
4'Flowers smaller, rarely exceeding 3.5 cm diam.; petals and anthers yellow
5Stems creeping, rooting at the nodes; perennial
5'Stems not rooting at the nodes, but sometimes diffuse or sprawling
6Flowers solitary, axillary or leaf-opposed; annual plants; flowers small and inconspicuous (except in R. marginatus and R. cornutus)
6'Flowers terminal; perennial plants; flowers usually conspicuous
7Achenes echinate or strongly muricate
7'Achenes muriculate, papillose or smooth, not echinate or strongly muricate
8Basal leaves spathulate-cuneate, dentate at apex; upper leaves with linear divisions; achenes with long slender spines; achene-margin at right angles to surface
8'Basal leaves reniform, deeply 3-7-lobed; upper leaves sometimes simple; achenes shortly echinate-muricate, with a broad flat marginal wing
9Peduncle shorter than adjacent leaf, incrassate in fruit; achenes narrowly bordered, with a short beak
9'Peduncle as long as, or longer than adjacent leaf, slender, not incrassate
10Achene narrowly bordered, and with a short (usually upturned) beak; upper leaves often simple or rather coarsely laciniate
10'Achene distinctly winged, with a prominent (often deflexed) beak; upper leaves laciniate with numerous linear-lanceolate lobes
11Inflorescence scapose, very sparsely branched, usually leafless or almost so; rootstock wholly or partly tuberous (grumose); achenes more than 2 mm long
11'Inflorescence branched, often leafy; if sparsely branched, then with achenes shorter than 2 mm (R. gracilis)
12Rootstock crowned with a "collar" of interwoven fibres (old, decayed leaf-bases); lower leaves often simple, broadly ovate-cuneate
12'Rootstock without a "collar" of fibres
13Leaves broadly reniform, palmately divided into blunt lobes; plant glabrescent, often tinged purple; petals 5-12 or more
13'Leaves deltoid, pinnately divided into small ovate or cuneate lobes; petals normally 5
14Sepals patent or adpressed to petals; tubers clavate
14'Sepals reflexed; tubers elongate-fusiform
15Achenes small, c. 1.5 mm long, with upturned beak
15'Achenes 2-4 mm long, with straight, recurved or hooked beak
16Plant glabrous or glabrescent; radical leaves broadly reniform or almost orbicular, rather leathery
16'Plant pubescent or villose; radical leaves broadly deltoid, deeply lobed or dissected, not leathery
17Radical leaves 2-3-pinnate, villose; peduncles divaricate, conspicuously incrassate in fruit; achenes forming a cylindrical head
17'Radical leaves broadly deltoid, 3-lobed or reniform, crenate and shallowly lobed; peduncles erect or ascending, not incrassate
18Achenes with a long, slender, straight or slightly recurved beak; root-tubers short, about 4-10 cm long
18'Achenes with a short, triangular or hooked beak; root-tubers elongate, 4-12 cm long, or wanting
19Radical leaves reniform, shallowly lobed; sepals not reflexed in flower
19'Radical leaves broadly deltoid, deeply 3-lobed or almost ternate; sepals reflexed in flower
20Achenes uniformly brown, without a margin; roots all fibrous, or at most slightly thickened
20'Achenes with a pale margin; roots intermixed with elongate cylindrical tubers
21Stock conspicuously swollen and corm-like; achenes finely punctate
21'Without corm-like stock; achenes smooth