Edita Štefanić

Phenological Variation in Ambrosia artemisiifolia L. Facilitates Near Future Establishment at Northern Latitudes

The invasive weed Ambrosia artemisiifolia (common ragweed) constitutes a great threat to public health and agriculture in large areas of the globe. Climate change, characterized by higher temperatures and prolonged vegetation periods, could increase the risk of establishment in northern Europe in the future. However, as the species is a short-day plant that requires long nights to induce bloom formation, it might still fail to produce mature seeds before the onset of winter in areas at northern latitudes characterized by short summer nights. To survey the genetic variation in flowering time and study the effect of latitudinal origin on this trait, a reciprocal common garden experiment, including eleven populations of A. artemisiifolia from Europe and North America, was conducted. The experiment was conducted both outside the range limit of the species, in Sweden and within its invaded range, in Croatia. Our main hypothesis was that the photoperiodic-thermal requirements of A. artemisiifolia constitute a barrier for reproduction at northern latitudes and, thus, halts the northern range shift despite expected climate change. Results revealed the presence of a north-south gradient in flowering time at both garden sites, indicating that certain European populations are pre-adapted to photoperiodic and thermal conditions at latitudes up to, at least, 60° N. This was confirmed by phenological recordings performed in a region close to the northern range limit, the north of Germany. Thus, we conclude that there exists a high risk for establishment and spread of A. artemisiifolia in FennoScandinavia in the near future. The range shift might occur independently of climate change, but would be accelerated by it.

Goldenrod: a valuable plant for beekeeping in north-eastern Croatia

Goldenrod, native to North America was introduced into Europe in the 19th centuary as ornamental plant. However, this plant has become widespread and is a serious invader of abandoned fields, forest edges and river banks. Goldenrod represents an important source of nectar for honey bees, particularly as a reserve to help colonies survive the winter period. Although is insect pollinated plant, it shed much more pollen than is carried off by insects. The pollen may become atmospheric and can cause hay fewer during its pollination period in August.

Plants for Bees: Silybum marianum

Other uses Milk thistle has a long history of use as a medicinal plant. The achenies (seeds) contain the biologically active flavonolignan complex silymarin that contains silyibin, silydianin, and silycristin. Pharmacological investigations have focused on the standardized sylimarin extract, and now, following decades of research, silymarin is reported to protect and regenerate liver cells in cases of alcoholic cirrhosis, hepatitis, damage from pharmaceutical drugs, mushroom poisoning and poisoning from environmental and occupational toxins. A commercial milk thistle product for pharmaceutical purposes is successful in many countries (Martin et al., 2006; Zheljazkov et al., 2006; Stefanic and Stefanic, 2008).