Equisetum variegatum Schleich. ex Weber et Mohr in Lithuania: habitat diversity, distribution patterns and environmental status based on herbarium collection

Abstract

Equisetum variegatum Schleich. ex Weber et Mohr (Equisetaceae  L. Rich. ex DC.) is a perennial evergreen plant with a long rhizome. It grows in Arctic tundra and mountain habitats. Usually E.  variegatum is assigned to rare or fairly frequent plant species in Lithuania. During the last six decades the number of E. variegatum localities increased more than tenfold. Therefore it is important to perform an analysis of E. variegatum distribution patterns, diversity of localities, and environment protection status in Lithuania. In order to analyse E. variegatum distribution and habitats, herbarium specimens of the horsetail in four Lithuanian herbaria as well as the data obtained during personal research were used. The analysis showed that E. variegatum is found in 27 of 60 administrative districts of Lithuania. Approximately 70% of E. variegatum habitats are anthropogenic, found mainly in the abandoned sand or gravel quarries. Three naturally occurring E.  variegatum habitat concentration zones were determined in south-eastern and western Lithuania as well as on the coast. Typical naturally occurring E.  variegatum habitats in Lithuania are wet meadows, lake shores, fen, coastal dunes, and pine forests. E. variegatum is rare or very rare in natural habitats and fairly rare or fairly common in anthropogenic habitats in Lithuania. In the latter habitats E. variegatum frequently forms thicket.