BOTANY WITH THE BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

X. SEED PLANTS

Sundew Family (Droseraceae)

Bog or aquatic herbaceous plants or subshrubs. Extremely rare and fascinating in their biology, these are Insectivorous Plants. In herbaceous forms, the leaves are gathered in a basal rosette and covered with various glandular hairs, bristles, or other outgrowths capable of secreting a sticky fluid. This fluid contains an enzyme that acts similarly to Pepsin and is capable of digesting protein substances. The flowers are bisexual, actinomorphic, solitary or arranged in racemes, with a 4- or 5-merous double perianth and most often the same number of stamens. The pistil is formed from three to five carpels, with a superior unilocular or bilocular Ovary. There are three to five styles.

Floral formula: *K_4-5C_4-5A_{5_20}G_(3-5). Fruit — a capsule opening with three to five Valves.

The family comprises five genera and 110 species distributed across Eurasia, the Mediterranean, and Australia. In Ukraine, the family is represented by two genera and four species.

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Fig. 131. Waterwheel plant (Aldrovanda vesiculosa)

Waterwheel plant (Aldrovanda vesiculosa L.). A perennial herbaceous insectivorous free-floating aquatic plant with a horizontally positioned, thread-like stem 5—15 cm long, lacking roots (Fig. 131).

Phyllotaxis is whorled. Leaves are small, arranged in whorls of six to nine, fused at the base. The leaf petiole is broad, with its apex covered by six awl-shaped bristles. The leaf blade consists of two semicircular halves that snap shut along the midrib upon contact. This mechanism captures small aquatic animal larvae and Other forms of zooplankton, which serve as nourishment for the plant. Several awl-shaped bristles are located on the leaves.

Flowers are solitary, 5—6 mm in diameter, located in the leaf axils. Petals are white, small, 4—5 mm long, on pedicels much longer than the leaves. There are five styles. Floral formula: *K5C5A5G(s). Fruit — a globose unilocular capsule. Seed is ovoid, black, smooth, about 1 mm long. Blooms above the water in June—July.

Distributed sporadically in the Precarpathian region, Polesia, the Forest-Steppe, and the Steppe zones in stagnant water bodies (lakes) and rivers (within the Dnieper river basin and the Danube delta). The species is protected and listed in the Red Data Book of Ukraine.