Ruellia simplex C. Wright

Raab-Straube, Eckhard von & Raus, Thomas, 2025, Euro + Med-Checklist Notulae, 18, Willdenowia 55 (1), pp. 107-144 : 109

Ruellia simplex C. Wright (= R. brittoniana Leonard ; = R. coerulea Morong ; = R. malacosperma Greenm. ; = R. tweedieana Griseb. ) – Fig. 1.

A Tn: Tunisia: Wilayah of Zaghouan, El Fahs, 36°23'N, 09°55'E, 180 m, by roadsides, 11 Oct 2018, El Mokni (Herb. Univ. Monastir); ibid., Wilayah of Monastir, Monastir City, 35°46'N, 10°49'E, 20 m, by roadsides near public gardens, 27 Oct 2022, El Mokni (Herb. Univ. Monastir). – Ruellia simplex , commonly known as “Mexican petunia” or “Mexican bluebell”, is native to Mexico, the Antilles (first described from Cuba), W Bolivia, SW Brazil, Paraguay, Uruguay and NE Argentina. From its disjunct occurrences it had been described several times as a species new to science; all those taxa, however, finally proved to be conspecific ( Fernald 1945; Ezcurra & Daniel 2007). According to Turland & al. (2018: Art. 60.8 and 60.9), the spelling of the published epithets “ tweediana ” and “ tweedyana ” is correctable to tweedieana , commemorating John Tweedie, 1775–1862 ( Coats 1969: 357–359). The species was introduced to Florida in the 1930s ( Hupp & al. 2009) and since then has become a very popular landscape plant appreciated for its prolific flowering and low maintenance requirements ( Gilman 1999). Due to its ability to grow in a wide range of environmental conditions, from wetlands to almost xeric ( Hupp & al. 2009), the high average of seeds produced per capsule and the high germination rate (98–100% un- der ideal conditions of 30°C day and 20°C night, Wilson & Mecca 2003), the species has naturalized in disturbed uplands and wetlands of the S United States and Hawaii ( Wunderlin & al. 2024). In the Mediterranean region the species is reported as casual only from Italy ( Iamonico 2022; Galasso & al. 2024: 301) and is not yet listed in The Euro+Med PlantBase ( Marhold 2011a +). The African Plant Database ( APD 2024b) lists the taxon merely as cultivated without specifying individual regions. Our report of R. simplex as a casual alien from Tunisia, locally escaped from ornamental cultivation, is the first for the African xenophytic flora. R. El Mokni & Th. Raus