Ranunculus aquatilis L.

Ranunculus aquatilis is very variable. In the past it has often been treated as three or four species and many varieties. These segregate taxa have been based on the size, petiolation and rigidity of the leaves (now known to be primarily under environmental control), petal size and curvature of the fruiting pedicel (both sometimes variable along single stem), and number of achenes per head and length of achene beak (which vary continuously and are not correlated with one another). Unless reliable characters can be found, only two of the taxa recognized in older floras can be maintained.

Stems glabrous. Leaves laminate and filiform-dissected; laminate leaf blades reniform, 3-parted, 0.4-1.1 × 0.7-2.3 cm, segments obovate or fan-shaped, shallowly cleft, margins crenate; filiform-dissected leaves with stipules gradually tapering upward, connate for their whole length. Flowers: receptacle hispid, rarely glabrous; sepals spreading or reflexed, 2-4 × 1-2 mm, glabrous; petals 5, 4-7 × 1-5 mm; style 0.1-0.8 mm. Fruiting pedicels usually recurved. Heads of achenes hemispheric to ovoid, 2-4 × 2-5 mm; achenes 1-2 × 0.8-1.4 mm, glabrous or hispid; beak persistent, filiform, 0.1-1.2 mm.

Batrachium aquatile (Linnaeus) Dumortier

Ranunculus aquatilis, the common water-crowfoot or white water-crowfoot, is a plant species of the genus Ranunculus, native throughout most of Europe and western North America, and also northwest Africa.

This is an aquatic plant, growing in mats on the surface of water. It has branching thread-like underwater leaves and toothed floater leaves. In fast flowing water the floaters may not be grown. The flowers are white petaled with yellow centres and are held a centimetre or two above the water. The floater leaves are used as props for the flowers and are grown at the same time.