Verbena brasiliensis Vell.: a new record of an invasive alien species in the flora of Turkey

Verbena brasiliensis , the Brazilian Vervain, is a flowering plant species from Verbenaceae family. It is native to parts of South America, but has spread its range in recent times. During floristic surveys in Bartın province in northern Turkey, a new alien species for the country ( Verbena brasiliensis , Verbenaceae) was found. Only two Verbena species were previously known from Turkey. We present an identification key and description of morphological characters of the species, as well as notes regarding the habitat where it was found.


Introduction
According to recent studies, Verbenaceae includes about 34 genera with approximately 1035 species, mainly distributed in tropical and subtropical regions, particularly in Southeast Asia, Central and South America and the West Indies, with few species occurring in the temperate zones (Gorshkova 1974;Leary 2006;Munir 2002;Xu and Chang 2017).Verbena L. was originally described by Linnaeus (1753) with 14 species.Since then, several authors worked on Verbena and today this genus is represented by 107 species, which are mainly spread in subtropical and tropical countries of America, some of them growing in Europe (Portugal, Italy, and Spain), Asia, Africa, and Australia (Yeo 1990;Kolakovskii 1986;Mikeladze et al. 2017;Almeida 1999;Soldano 2000;Verloove 2006).
In Turkey, two species of Verbena have been recorded until today.These are V. officinalis L. and V. supina L. (Townsend 1982;Güner et al. 2012).With this study, a third Verbena species is recorded as a new alien species for the country.

Materials and methods
During the field studies around the Bartın province in northern Turkey, plant samples belonging to Verbena were collected in June 2020.The collected samples were checked according to the Flora of Turkey and its supplements and according to A Checklist of the Flora of Turkey (Vascular Plants) (Townsend 1982;Davis 1988;Güner et al. 2000) and after a detailed review of the literature they were identified as Verbena brasiliensis (Townsend 1982;Güner et al. 2012;Uludağ et al. 2017;Perry 1933).The collected specimens were deposited in the Bartın University Ulus Vocational School Plant Samples Laboratory and Herbarium of Duzce University Faculty of Forestry (DUOF).
In this study, the morphological description of Verbena brasiliensis was based on the available literature (Yeo 1990;Perry 1933) and the microscopic examination of collected plants as herbarium material.The distribution map of V. brasiliensis in Turkey was created according to the grid system in Flora of Turkey (Townsend 1982).Data on the spread of species, condition of the populations and characteristics of the habitats inhabited by V. brasiliensis in Turkey are based on field research and presented in this article.

Habitat and distribution in Turkey
Turkey (Western Black Sea Region; Figure 2): A4-Bartın, Karasu village of 0-10 m, 41°40′N; 32°14′E, roadside and ruderal areas, 29.05.2020,B. Tunçkol 5850.Flowering time late spring and summer (May-July).It spreads in ruderal areas along the roadside in an area of almost 20 ha in groups.In the habitat where Verbena brasiliensis grows, the following species accompany it: Capsella bursa-pastoris (L.) Medik., Cardamine hirsuta L., Cerastium Verbena brasiliensis is similar to V. litoralis and V. bonariensis but apparently, it is distinguished by the difference in inflorescence.The spikes of V. brasiliensis are short, compact, sessile, and regularly arranged in open cymes, whereas those of V. litoralis and V. bonariensis are longer, compact or somewhat elongated, pedunculate, and arranged in more or less paniculate cymes (Perry 1933).
Invasive species are one of the greatest threats to natural biodiversity and the sustainability of ecosystems.Accordingly, this newfound naturalized alien species suppresses the growth of natural herbal plants in the area.There is a Filyos river which is a stopover used by migrating birds in the area, so it is estimated that these birds disperse the seeds of the plant.It is possible that this new recorded alien species can be seen in other regions of Turkey and continue to suppress the natural flora.Therefore, the spread of alien species except for natural conditions and their transition from one country to the other should be kept under control.

Figure 1 .
Figure 1.Verbena brasiliensis Vell. A. Habit in the field.B. Flower-spike with subsidiary spike.C. Two vegetative internodes of main stem.D. Flowers.Photographs by B. Tunçkol.

Figure 2 .
Figure 2. Distribution map of Verbena brasiliensis in Turkey.