Two alien species in the spreading process in Romania: Reynoutria x bohemica Chrtek & Chrtková and Grindelia squarrosa (Pursh) Dunal

Abstract

This paper presents two alien plant species, recently immigrated in Romania (Reynoutria x bohemica Chrtek & Chrtková and Grindelia squarrosa (Pursh) Dunal). For each species, the following information was provided: occurrence in Romania, way of migration, their distribution in Romania, Europe and other continents, general aspects regarding their biology, ecology and invasive character. Reynoutria x bohemica was mentioned in the flora of Romania by Kovács (2004) and Fenesi (2004), as an important element of the perennial synanthropic vegetation of mesic habitats. In our recent field investigations (between 2004 and 2007), we have also identified this alien species in Moldavia (Romania), where it was not known until now, especially along watercourses from the mountainous region (Bistriţa and Moldova Rivers). Moreover, the study of samples from some herbaria (I, IAGB and IASI) allowed us to find out that, although the occurrence of this species in Romania was discovered a short time ago, it had already been collected since the second half of the last century, but was erroneously determined as Polygonum cuspidatum Sieb. & Zucc. In the conquered habitats, Reynoutria x bohemica manifested a marked invasive character, forming well-developed phytocoenoses (2-4 m high and 100% coverage), which replaced the native vegetal communities on large areas. The second species, Grindelia squarrosa (reported in 1998 for the first time in the flora of Romania), can be also considered as an invasive alien plant in Romania. It invaded the disturbed habitats (especially ruderal places in the proximity of railways), both in the North-East and South of Moldavia (Iaşi and Galaţi).