Symphyotrichum ciliatum an Invasive Species in the Romanian Flora – Contributions to the Knowledge of the Vegetative Organs Structure

Abstract Symphyotrichum ciliatum (Ledeb.) G.L. Nesom is an adventive plant first reported in Romania in 1967, which has spread rapidly over the last few decades in Moldova, Muntenia and, more recently, in Transylvania. Although the species has been known for a while in Europe and Romania, there is no information about the anatomy of the vegetative organs of this invasive taxon. This paper presents a series of structural aspects of the vegetative body, of Symphyotrichum ciliatum collected from a sandy and salty substrate (Sacalin Island - Danube Delta). These demonstrate the ability of this plant to adapt to the environment and its capacity to achieve a wide spread. As such, although this plant is an annual species, the root and stem achieve secondary growth in their width, which offers robustness to the corm; the palisade tissue has an ecvifacial disposition which enhances efficiency in capturing light, especially on sandy soil that reflects light; there are aeriferous and aquiferous formations that ensure efficiency in adapting to a wet and relatively salty environment. These results are documented by original photographs of optical microscopy and a distribution map of the taxon in Romania as at 2011.