Utricularia vulgaris

Common throughout Finland, except rare in Northern Lapland.

Perennial, rootless, herbaceous insectivorous aquatic plant.

20–100 cm long.

The stem is free-floating, prostrate. In the autumn, there are ovoid, 3–6 mm long, densely foliate turions at the apices of the branches.

The leaf arrangement is spiral. The laminae are compound and laciniate. All the leaves of vegetative branches photosynthesize and bear bladders. The leaves are dark green – brownish – reddish in color. The lamina is two or three times laciniate. The lobes are 0.1–0.3 mm wide, typically without venation. The segments are serrulate with 5–10 cuspidate teeth. Each tooth has one or two cusps at the apex. A cusp is 3–12 times longer than its tooth.

The bladders (2–3 mm) are at the apices of the lobes of the leaves. The inside of a bladder is covered with sessile, four-branched stellate hairs (two of the branches are long and the other two are short). The branches of the stellate hairs are 9–12 µm wide. The long and short branches are nearly parallel, and the angle between same type of branches is typically 85–130°. There are two-branched stellate hairs at the mouth of the bladder.

There are scale-like upper leaves at the distal part of the floral branch.

The floral branch is 10–25 cm high and erect, with two or three rhizome-like 3–22 mm long branches at the base. The rachis is straight. The inflorescence is a raceme with 5–10 flowers. The flowers are bisexual, with connate floral parts, zygomorphic and subtended by bracts. The pedicels are 8–15 mm long, two to three times longer than their bracts, and deflexed. The calyx consists of two sepals. The corolla is dark yellow and bilabiate. The upper lip is about 11 mm long. The lower lip is 13–15 mm, saddle-like in form, with revolute margin and a deflexed, about 8 mm long spur. The throat of corolla is closed by the palate of the lower lip. The flower has two stamens. The ovary is superior.

The capsule (2–4 mm) contains many seeds.

Flowers in midsummer and late summer (VI–VIII).

Sheltered, shallow pools on the shores of oligotrophic to eutrophic lakes, rivers and brackish water bays, small lakes, bottoms of bays, pits, streams.