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

IX. VASCULAR CRYPTOGAMS (HIGHER SPORE PLANTS)

Class Horsetails (Equisetopsida)

The Class is represented by two orders: the fossil Calamitales and the extant Equisetales. The order Equisetales comprises a single family, Equisetaceae, with one extant genus, Equisetum, numbering about 30 species. There are 9 horsetail species growing in Ukraine. Water horsetail and marsh horsetail belong to aquatic and wetland plants.

Fig. 98. Water horsetail

Water horsetail (Equisetum fluviatile) is a herbaceous, rhizomatous plant 30-150 cm tall (Fig. 98). Synonyms of the Latin name for water horsetail are E. limosum and E. heleocharis.

Stems are simple or branched, smooth, up to 8 mm thick, with 9-30 slightly convex ridges and a wide central cavity. The sheaths, formed by connate leaves, are pressed against the stem, shiny; the lower ones are black and crowded, while the upper ones are green and distant. The Teeth are triangular-subulate, black, with a narrow white border.

Water horsetail grows in soft-water bogs, along the banks of ponds, lakes, and rivers, in shallow water and at greater depths. Spore maturation occurs in June - August.

Shoots of water horsetail serve as excellent forage for muskrats, beavers, and ducks. Muskrats harvest large stores of this plant for the winter.

Marsh horsetail (E. palustre) is a perennial herbaceous plant (Fig. 99) 15-50 cm tall, with a stem up to 3 mm thick, often branched, bearing 4-12 very convex ridges, a narrow central cavity, and a rough surface. Sheaths are cylindrical, funnel-shaped at the top, green. Teeth are triangular-lanceolate, acute, blackish-brown externally, with a wide white border. It grows in bogs, waterlogged meadows, and along the margins of ponds, lakes, and rivers. Spores ripen in June - July.

Fig. 99. Marsh horsetail

The plant is toxic to cattle and horses. Poisoning by marsh horsetail is frequently a cause of animal mortality. Livestock usually avoid eating fresh plants in pasture. Hay containing a high admixture of marsh horsetail causes equisetosis, better known as "staggers" or "equine staggers". The plants may be eaten by beavers.