Chorological data regarding the presence of Corylus colurna species in Romania

The Turkish hazel or Turkish filbert (Corylus colurna) is a less widespread tree species in Romania. Data on the presence of C. colurna species in the Romanian flora are quite rare. The article’s aim is to analyse the scientific information and those of the main herbariums regarding the presence of C. colurna species on the Romanian territory. The presence of the species on the Romanian territory was signalled about 122 years ago in the paper “Conspectus of Romanian Flora”. Subsequent scientific information identifies the species in different locations, especially in the southwest of Romania, in dendrological and natural parks. Scientific importance of the species lies in its rarity, the species has an area limit on Romanian territory and in the value, it gives to natural ecosystems in which it grows. The practical value is given by its edible fruits, valuable from a food or medicinal point of view and by its agronomic characteristics. As a result, the biodiversity conservation strategy should include forest protected areas as important objectives.


Introduction
Corylus genus belongs to Corylaceae family (Dihoru, 1975;Beldie, 1977;Ciocârlan, 2000Ciocârlan, , 2009 or Betulaceae family (Prodan, 1939;Georgescu, 1952;Prodan and Buia, 1966;Resmeriță, 1970). Corylus genus represents a diverse group of useful woody plants, ranging from small, multi-stemmed shrubs to tall, stately trees, all of which produce edible nuts (Molnar, 2011). Corylus genus is widely distributed across temperate regions of the Northern Hemisphere, with species found in Japan, Korea, and China, through Tibet, India, Northern Iran, Turkey, the Caucuses, Europe, and North America (Molnar, 2011). Corylus colurna L. (Turkish hazel or Turkish filbert) and C. avellana L. (Common hazel) are the most common hazel species in Europe (Riethmueller et al., 2014). C. avellana L., which has a wide distribution, while, C. colurna L., restricted to the Balkans, Romania, and Northern Turkey (Thompson et al., 1996). In spontaneous flora of Romania, Corylus genus is represented by 2 species: C. avellana L. and C. colurna L. In southern regions of Romania there is also C. maxima Mill. cultivated as well, a taxon synonymous with C. avellana, the difference between them being at the level of involucre (Mehlenbacher, 1991;Thompson et al., 1996;Erdogan and Mehlenbacher, 2000a, b). The spreading of C. colurna in Romania is quite small, only in Banat and Oltenia and Vâlcan Mountains is its northern limit of the area (Boruz et al., 2013). Corylus avellana is commonly found in both national and European levels. C. avellana is widely distributed in Europe, in natural stands ranging from Scandinavia to the south of the continent (Palmé and Vendramin, 2002). In the north it can be found in Norway up to 67°N, although its northern limit decreases further to the east (Deacon, 1974). It is the first species to colonize the European continent since the last ice age, as evidenced by studies on pollen and chloroplast (Palmé and Vendramin, 2002;Boccacci and Botta, 2009). C. colurna is a calcicolous species that has its origin in the Balkans (Boruz et al., 2013) and is a member of the Europe-Siberia flora region (Molnar, 2011). C. avellana is the only cultivated species and contains a great amount of genetic diversity (Rovira, 1997). C. colurna is one of the common species in Turkey (Aydinoglu, 2010). Beside scientific information, also valuable information on the presence of certain species in certain ecological areas is obtained from herbarium collections. Herbal collections have a scientific, didactic, educational, and also informative value. The collection of plants began in the 16th century. Later, J.P. Tourefort (ca 1700, France) used the term "herbarium" for plants (Bridson and Forman, 1999). One of the oldest herbariums in South-Eastern Europe, a pre-Linnaean herbarium dating from 1734, is in the botanical collection of the Natural History Museum within Brukenthal Museum (Sibiu, Romania). Their purpose is important because they provide information about plants and their area of spread during long periods that help to carry out studies in taxonomy, biodiversity, ecology, anatomy, morphology etc. (Vechiu and Dinca, 2019). Evidence of the hazelnut species spread is the information presented in various herbariums. The aim of this article is to analyse the scientific information and the main herbariums regarding the presence of C. colurna species on the Romanian territory.

Materials and Methods
The material used to carry out this paper consisted in specialized sections that contained the species Corylus colurna in the floristic list or in the composition of some phytocenoses, according to the herbarium data from the main herbariums in the country (Bucharest, Cluj-Napoca, Iași and Craiova). The material is based also on the analysis of the data obtained following the trips made in different resorts where they are vegetating. The acronyms used for the herbariums consulted are: BUCA (Herbarium of Biology Institute of the Romanian Academy), CL (Herbarium of "Babeş-Bolyai" University Cluj-Napoca), I (Herbarium of "Al. I. Cuza" University Iași) and CRA (Herbarium of Craiova University). A data base for C. colurna was realized, focusing on the following data: plate number; Herbarium/Botanic Collection/Institution; Species name; Harvesting date; Harvesting place; the person who has collected the plant; conservation grade, coded with numbers from 1 to 4 (1 = well preserved plant, 2 = plant with parts detached from the plate, but still present, 3 = plant detached from the plate, with missing parts and 4 = plant detached and fragmented, with over 50% of its parts missing) (Vechiu and Dinca, 2019). For localities mapping was used the UTM Code, according to Lehrer and Lehrer (1990). The distribution maps of the species were obtained using Corolog 2010 Program, realized in Biology Institute of Bucharest. The program uses a data base access, with information from literature, herbarium and field and two types of maps, the maps of annual average temperature and precipitation in Romania. The Stereo 70 coordinates corresponding to the points where plant material was collected were inserted in the table.
Results and Discussion C. colurna (Turkish hazel) is a less widespread tree species in Romania. Data on the species C. colurna in the Romanian flora are sporadic until the publication of the paper "Conspectul Florei Romaniei" (Grecescu, 1898) which speaks of C. colurna as a fairly common species in the Balkan Peninsula, which is found only in Mehedinti to Verciorova and Banat. Prodan (1939) in the paper "Flora for determining and describing the plants growing in Romania" states that there are 3 species of Corylus in the Romanian flora (C. avellana, C. colurna and C. maxima) and in C. maxima he gives C. tubulosa Willd. as synonymous. In Flora României (volume I, 1952, pp. 197-202), Georgescu (1952) mentions the same 3 species: C. avellana, C. colurna and C. maxima. In 2 of them he presents intraspecific variability. In C. colurna the variety glandulifera (C. Koch) A. DC is mentioned, and in C. avellana, the typica form C. K. Schn. Laubholzk. with the subforms: brachychlámys Spach and schizochlámys Spach. About C. maxima it is only stated that it is cultivated, but rarely. Prodan and Buia (1966) in "The small illustrated flora of Romania" in Corylus genus they mention 3 species. In each species the main morphological characters, the flowering and fruiting period and the ecology are presented, and in C. avellana the cenotic affiliation is also given. Beldie (1977) also quotes 2 species (C. avellana and C. colurna) in the paper "Flora of Romania -illustrated determinator of vascular plants" (pp. 79-80). Each key taxon has the main differentiating characters, lifespan, biological form, height, flowering period, spread over areas and floors of vegetation, resorts where they can be found, soil type, trophicity and geo-element. In "The illustrated flora of Romania Pteridophyta & Spermatophyta" shows the presence of 3 species, 2 spontaneous (C. avellana and C. colurna) and one cultivated (C. maxima). Among the analysed plants by the authors new data on the chorology of their Corylus species were also found in various synthesis papers that had as object of study the flora and vegetation of a certain territory. Information on the spread of C. avellana: Pop (1968) in the Crisurilor Plain is frequently presented; Resmeriță (1970) in the Vlădeasa Massif; in the Eastern Carpathians (Oprea and Sîrbu, 2009); Rodna Mountains by Coldea (1990) etc. C. avellana species has a good representation in the literature. It was mentioned by Cârțu (1969) from in Amaradia river basin, by Cârțu (1972) in the area between Jiu-Desnățui-Craiova and the Danube, by Năstase (1982) in Bucovăț forest, by Karácsonyi (1995) in Satu-Mare county, by Oroian (1998) in Mureș Gorge, between Toplița and Deda, by Negrean et al. (2017) in Salaj county. These last authors also identified the C. colurna species in several points: Șimleul Silvaniei N, Măgura Șimleului, Băile Iaz. Data on the presence of C. colurna in Romania are rare. Near Oravița (Romania) exists a big stand (80 ha) of C. colurna, the maximum data of age was 329 years (Richter, 2016). C. colurna was identified in the Iron Gates Park (Mehedinți) and Cheile Nerei-Beușnița National Park (Caraș-Severin) by Borlea et al. (2006) in the forest of Domogled (Băile Herculane, Romania) by Manoiu et al. (2015) and Ștefan et al. (2013). C. colurna was also identified in arranged dendrological parks, parks that include a several plants, very rare, in Bistrița (Rusu and Gavriloaie, 2011), in "Bazoș Arboretum" protected area (Cadar et al., 2014), in Cheile Nerei-Beușnița Site (Biri et al., 2016). Turkish hazel is a tolerant semi-shade tree species that can create mixed stands with other species and has a low level of invasion potential (Šeho et al., 2019).  (Boruz et al., 2013) and is found in different parks, in areas favourable for the cultivation of this species. The presence of C. colurna species is also indicated by Bușe Dragomir and Nicolae (2014) in the Iron Gates park, Mehedinți. Turkish hazel has been found sporadically in forest habitats in Central, Eastern and Western Serbia (Mitrovic et al., 2001). Therefore, the remaining Turkish hazel populations in different locations are of critical importance, and the genetic conservation of this species plays a key role in the sustainable development of forests. Corylus species have scientific and practical importance. C. colurna has no relevant economic importance, but agronomic characteristics are very important, it does not produce basal shoots, an important aspect for hazelnut cultivation (Avanzato, 2008). Biodiversity conservation strategy should include forest protected areas as important objectives (Borlea et al., 2006).

Conclusions
In conclusion, the presence of C. colurna species on the Romanian territory is signalled about 122 years ago in the paper "Conspectus of Romanian Flora". Subsequent scientific information identifies the species in different locations, especially in the South-Western Romania, in dendrological and natural parks. Scientific importance of C. colurna species lies in its rarity, the species has an area limit on the territory of Romania and in the value, it gives to the natural ecosystems in which it grows. The practical value is given by the edible fruits, valuable from a food or medicinal point of view and by its agronomic characteristics (it does not produce basal shoots).

Authors' Contributions
Conceptualization of research (SC, DR); Design of the experiments (SC); Contribution of experimental materials (DR); Analysis of data and interpretation (SC, DR); Preparation of the manuscript (SC, DR). Both authors read and approved the final manuscript.