Contribution to the Knowledge of the Alien Flora from Romania: Rudbeckia triloba L. and Senecio inaequidens DC.

Abstract

Two alien species new to the Romanian flora, namely Rudbeckia triloba L. and Senecio inaequidens DC (Asteraceae family) have been recorded during 2004-2009 period in different places of Moldavia and Maramures provinces (Romania). Rudbeckia triloba, native of North America, is a perennial species, 150 cm of length, with glabrate stems, blades ovate to subcordate or elliptic leaves, which present serrate margins. The capitula (10-30) is long pedunculate, with conic to subhemispheric receptacles (8-150-15 mm); with the paleae dark purple (5-6.5 mm). The ray florets are 7-15; the laminae is yellow-orange, linear to oblanceolate, 8-17 3-8 mm. The other species, Senecio inaequidens, is native of South Africa and it is a perennial herb. The cross pollination with non-specialized insects ensures the production of a large number of seeds, but self-pollination populations have also been reported, increasing the chances of the species to colonize new territory, where other sources of pollen were missing. Though for the moment these two species are sporadically met among the Romanian flora, at least one of them (Senecio inaequidens) might become in the near future a threat to the natural or agricultural national ecosystems.