Research Article |
Corresponding author: Irakli Mikeladze ( irakli.mikeladze@bsu.edu.ge ) Academic editor: Ketevan Batsatsashvili
© 2023 Irakli Mikeladze, Gia Bolkvadze.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Mikeladze I, Bolkvadze G (2023) New distribution records of the alien plant – Sicyos angulatus L. (Cucurbitaceae) from Georgia. Caucasiana 2: 9-13. https://doi.org/10.3897/caucasiana.2.e96039
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The invasion of alien plants into the territory of Georgia started in ancient times and continues today. Sicyos angulatus L., a species of North American origin, is an example of such an invasion. The first established populations of S. angulatus occurrence in Georgia were observed in 2012. Since then, new localities have been recorded, both in agricultural and disturbed natural communities. The species, which has easily adapted to local soil and climatic conditions, is expanding every year and is already widely spread in west Georgia. The plant is characterized by fast and intense growth and a climbing habit using other plants as a support. In this contribution, the peculiarities of its distribution in Georgia and the morphological features and life-history characteristics of Georgian populations are provided.
Alien plant, Invasive species, Chorokhi Delta, Kolkheti Lowland.
The genus Sicyos L. is the most diverse genus in the Cucurbitaceae family. It was proposed by
The natural distribution of Sicyos angulatus is the eastern part of North America (
According to Vasilchenko (
The materials were collected during the conventional route survey, which included plant description, photography, plant sampling, laboratory processing, herbarium preparation, and curation throughout the known and plausible areas of the species' distribution. In particular, river valleys, roadsides, agricultural lands, landfills, and wetlands were investigated during the irregular field trips in the period of 2012-2022.
Sicyos angulatus L., Sp. pl. 1013 (1753), is an annual herbaceous vine, 4-10 m long, completely fading in the coldest months of the year. Stem angular, pubescent, with 3–4 diverged tendrils. The maximum length of the plant (stem) recorded in Georgia is 16 m.
Leaves are simple, palmately veined, 5-lobed, alternately arranged, up to 25 cm across and borne on stout, pubescent petioles 2.5 to 10 cm long. The plant stem and the underside of a leaf along the petiole are pubescent. The petiole is generally 5 cm long. The root system consists of a shallow branched taproot (Fig.
Sicyos angulatus climbs with axillary tendrils bearing three or four branches. Branches of a tendril originate 2-5 cm above the base of the tendril. When the tip of the tendril makes contact with a support, it wraps or hooks around it, securing the tendril. Proximally to the contact point, the tendril then begins to twist, forming spirals. It has an unusual ability, known as perversion to form spirals, first in one direction and then further in the other.
Flowers are monoecious, with both staminate and pistillate flowers generally arising from the same axis on pubescent peduncles. The peduncles of the pistillate flowers are generally the same length as the pedicels, whereas the peduncles of the staminate flowers are several times longer than the pedicels. Calyx is green, five-toothed, pubescent. Corolla is white, green-striate, consists of five petals fused at the base into an open bowl, free and spread at the tips. Staminate flowers form on paniculate or racemose inflorescences. The anthers unite to form a central column. Pistillate flowers are borne on a compact cyme, in a globose cluster of 8-20 flowers. The pistil consists of a superior ovary, a slender style, and 3 stigmas (
Fruits are clustered, radiating from the central point, and appear as a single fruit with broad spikes. These clusters are 2.5-3.7 cm across. In fact, each ‘spike' is a single fleshy fruit (a berry), dry and dehiscent at maturity, with one seed inside and a single style at the tip. Each fruit is 1.1-1.7cm long, covered with sharp, white prickles, containing a single large seed. The seed is brown, flat, tapered at one end, never fully released from the fruit. Thus, what appears to be a seed at dispersal is a single mature ovary with one seed inside.
Sicyos angulatus
is an annual plant that spreads mainly by reseeding itself. Seeds are produced in large numbers: 4500-78000 seeds per plant (
Three species from two genera (Bryonia L. and Ecballium A. Rich.) of the Cucurbitaceae family have been described in the Georgian natural flora (
According to field studies in the distribution area, Sicyos angulatus has quite large populations on moist and wet soils. The average number of individuals is 12-18 per 1 m2. The average height is 6-8 m, although there are 12-16 m tall specimens recorded. The plant is characterized by development of numerous side shoots. Finally, the coverage at each invaded site increases to 90-95%. It climbs over every plant encountered and hinders its development (personal observation). In agricultural croplands: maize fields and citrus plantations, it significantly reduces the qualitative and quantitative characteristics of the harvest. Another problematic property of S. angulatus is its spiny fruits, as they cause human skin irritation upon touch. The species expands its distribution area with each subsequent growing season. The climatic conditions of west Georgia are advantageous for the continued invasion of S. angulatus, which increases harm to agricultural lands and already disturbed communities, and becomes more noticeable every year.
Sicyos angulatus
was first found in Georgia in 2012. The finding was reported on by
Since 2012, the plant has spread widely on the lowlands of Kolkheti, in river valleys, in wetlands, in agricultural croplands - mainly in maize fields, in citrus plantations and homesteads. The plant adapts well to local soil and climatic conditions, grows, blooms, bears fruit, matures seeds, and expands its distribution area every year. Despite its annual life cycle, it is characterized by fast and intense growth, a climbing habit, and behaviors that make it a highly invasive species. The effect of Sicyos angulatus on biodiversity as well as the local economy has not been quantitatively studied. However, the species might cause significant losses and need to be further studied and monitored.
We would like to thank Prof. Keti Batsatsashvili and Prof. Levan Mumladze (both from Ilia State University, Tbilisi, Georgia) for their extensive help in the preparation of manuscript.