Photo 1. A specimen of the newcomer species of thistle in a forest stand at Lepenice, not far from Gornje Jelenje, photographed in the fall of 2016. The candelabra thistle is easily identified by its rapid growth, candelabra-like branching, very spiny stems and leaf blades, and slightly shiny leaves. The fairly small flowerheads consist of creamy-white tubular flowers. (Photo by M. Randić)

CANDELABRA THISTLE (Cirsium candelabrum Griseb.)

In Croatia, the candelabra thistle (Cirsium candelabrum) was first discovered in the period 2008 – 2010 by the botanist Prof Jasenka Topić, PhD, in central Dalmatia, to where this species spread from Bosnia and Herzegovina in all likelihood. A few years earlier (in 2002 near Logatec) the newcomer species was also spotted in Slovenia where it continues to spread (Peter Grošelj, 2012). Croatian botanists further contributed to monitoring the plant’s expansion and studying its ecology and phytocoenology (Jasprica et al., 2015). Last summer we observed several specimens of this robust and easily identified thistle in the area above Gornje Jelenje and on Mali Platak.

The candelabra thistle is naturally distributed in the Balkans. In Croatia and Slovenia, however, it is a newcomer (adventive) species, spreading relatively quickly and exhibiting certain invasive features. At present, it mostly grows on excavations alongside roads in well-lighted and dry localities.

In the summer and fall of 2016, we came across several blossoming specimens of candelabra thistle on glacial till that was excavated during the reconstruction of the road leading to Platak, not far from the outlook at Mali Platak. We also found one specimen in a forest stand in the Lepenice region, about 1.5 km northeast of the Gornje Jelenje road pass. This forest stand, with prevailing beech trees, was heavily damaged in an ice storm in early 2014, resulting in reduced tree crown coverage and the dry carbonate soil of the forest floor is now covered in many herbaceous plants. The candelabra thistle is one of the plant species that has found a favourable habitat here.

Although we can assume that the candelabra thistle found on the new sites at the edges of Gorski Kotar spread into the region from Slovenia, this is still an open question. This season (2017) we will focus greater attention on the possible expansion of this newcomer species in the territory of the County of Primorje and Gorski Kotar and we will also try to take a better and more instructive photograph of the plant.

Marko Randić

Link:

http://hirc.botanic.hr/fcd/DetaljiFrame.aspx?IdVrste=30938&taxon=Cirsium+candelabrum+Griseb.

References:

Grošelj, P. (2012): Cirsium candelabrum Griseb.: Novo nahajlišče tujerodne vrste v Sloveniji. Hladnikia 29: 51-54.

Jasprica, N., Milović, M. et Pandža, M. (2015): Picrido hieracioides-Cirsietum candelabri Jasprica et al. 2015 – a ruderal association new to Croatia. Glasnik Hrvatskog botaničkog društva 3(2): 4-14.

Photo 2. Because of the damage caused to the crown cover by an ice storm, the beech stand at Lepenice has become a new site of the candelabra thistle in Croatia (Photo by M. Randić)