Sida rhombifolia L. – Fig. 6.

A Gg: Georgia: Guria region, Ureki–Magnetiti, nameless small street connecting Taqaishvili Street and main lateral street, 41.9957556°N, 41.7632444°E, 5 m, eleven small shrubs, 26 Aug 2022, Novák (BRNU photo [Fig. 6] + herbarium specimen revised by G. Tavilla); ibid., Imereti region, Vartsikhe, Ajameti Managed Reserve, 3.2 km ESE of Vartsikhe monastery, 42.1472467°N, 42.7536211°E, 115 m, 28 Aug 2022, roadside in forest c. 20 small shrubs, Novák, Pustková, Sedláček, Štětková, Szokala & Večeřa (obs.).

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– Sida rhombifolia is a perennial weedy species probably spreading in the Mediterranean region, actually known from Italy and Spain (Cambria & al. 2022). It is distributed in tropical, subtropical and warm-temperate parts of the world, but its native range remains unknown, probably located in the palaeotropics (Verdcourt 2004). It prefers open, especially ruderal habitats (roadsides, abandoned farmland, seasonally flooded territories or gardens). The new sites are situated in the humid warm-temperate Colchic lowland of W Georgia, SW Caucasus. Both populations appeared relatively well established, consisting of woody shrubs c. 1.3 m tall. Presumably S. rhombifolia has been introduced accidentally to Georgia. The seeds of Sida L. are dispersed by wind, humans, animals and rainwater, and those of S. rhombifolia are frequently disseminated when their barbed awns stick to animals, clothing and other objects. In Georgia, the species has spread probably by seeds carried on vehicles linked to commercial activities (e.g. grain importation) or on migrating birds. The plants inhabit slightly trampled vegetation of the phytosociological class Digitario sanguinalis-Eragrostietea minoris Mucina & al. (Mucina & al. 2016), accompanied by Cynodon dactylon (L.) Pers., Paspalum dilatatum Poir., Perilla frutescens (L.) Britton, Solanum pseudocapsicum L. and Sporobolus indicus (L.) R. Br. The only species of Sida previously reported from Georgia is S. spinosa L., an annual alien weed (Valdés & Raab-Straube 2011 +). Further spreading of S. rhombifolia across W Georgia is predictable, similar to numerous other subtropical and tropical species, due to the favourable climate of the region, which is warm-temperate and humid all year round (Ponert 1977; Sharabidze & al. 2018).

P. Novák & G. Tavilla