Praxelis clematidea King & Robinson (1970b: 194)

Christ, Anderson Luiz & Ritter, Mara Rejane, 2019, A taxonomic study of Praxelinae (Asteraceae-Eupatorieae) in Rio Grande do Sul, Brazil, Phytotaxa 393 (2), pp. 141-197 : 145-148

1.1. Praxelis clematidea King & Robinson (1970b: 194) .

Eupatorium clematideum Grisebach (1879: 172) nom. illeg. non (Wallich ex Candolle 1836: 191) Schultz-Bipontinus (1866: 258) (= Eupatorium reevesii Wallich ex Candolle 1836: 179 ), nec Lessing ex Baker (1876: 256) nom. nud. pro syn. (= Mikania phaeoclados Martius ex Baker 1876: 256 ). Eupatorium urticifolium var. clematideum Hieronymus ex Kuntze (1898: 148) . Eupatorium catarium Veldkamp (1999: 121) . Lectotype (designated by Freire & Ariza Espinar 2014a: 404):— ARGENTINA . Cordoba, s.d., P.G. Lorentz 81 (GOET! [GOET001494], isolectotype GOET [GOET001493]). ( Fig. 2A–D , 3A–C )

Subshrubs or rarely shrubs, up to 1 m tall, erect, branched from base or only in capitulescence; stems hirsute, rarely glabrous to glabrescent. Leaves 2.3–6.7 × 1–3.6 cm, petiolate; leaf blade ovate, chartaceous, apex acute to obtuse, base attenuate to cuneate, rarely rounded, margins serrate, adaxial surface strigose to rarely glabrescent, abaxial surface strigose to hirsute, petioles 0.4–1.8 cm long, hirsute, eglandular. Primary capitulescences corymbose. Secondary capitulescences paniculate, axis bracteate, bracts 1.2–5.4 × 0.5–3.4 cm, petioles 0.2–1.4 cm long, hirsute, eglandular. Capitula sessile to subsessile; peduncles up to 0.7 cm long, strigose to hirsute; involucres 6.2–8 × 3.8–5.1 mm; involucral bracts 17–25, 2–3-seriate, outer 3.1–5.7 × 0.9–1.6 mm, apex citrine to pink, glabrous, abaxial surface stramineous to citrine, 3–5-veined, glabrous, inner oblong to linear, 5.6–7.5 × 0.8–1.3 mm, apex acute to acuminate, sometimes attenuate, citrine to pink, glabrous, abaxial surface stramineous to citrine, 3–5-veined. Florets 32–44, corollas 3.1–4.5 × 0.4–0.7 mm, lilac, lobes glandular or eglandular. Cypselas obconical to rarely biconvex, 2–2.5 × 0.5–0.9 mm, 2–4-ribbed, ribs setuliferous, rarely glabrous, sinuses glabrous to puberulous, pappus setae ca. 20–31, white, 3.4–5.1 mm long.

Distribution: — Argentina , Bolivia, Brazil, Paraguay and Peru, and invasive in several other countries ( Abreu 2015). In Brazil, it occurs in all states besides Amazonas and Amapá. In Rio Grande do Sul, it occurs in the physiographic regions of Alto Uruguai, Campanha, Depressão Central, Litoral and Missões ( Fig. 4 , triangles).

Habitat: —Anthropogenic environments in biomes Atlantic Forest and Pampa.

Phenology: —Flowers through the year, with a flowering peak from December to March.

Etymology: —The specific epithet is a reference to the genus Clematis L. ( Ranunculaceae ), to which this species bears some morphological similarity.

Comments: — Praxelis clematidea is a ruderal species, common in anthropogenic sites, such as roadsides and wastelands. This species is also invasive and rapidly spreading in other countries and continents, like North America ( Abbott et al. 2008), Australia, Hong Kong and Taiwan ( Teles et al. 2016).

There are countless identification mistakes regarding this species and P. diffusa (syn. P. pauciflora (Kunth) R.M. King & H. Robinson ). Both species are morphologically very similar, and the features traditionally used to distinguish between them (length of peduncles and general appearance of the capitulescences) seem to be too variable to be used as diagnostic. In addition, the studied specimens and the methodology used here do not allow a deeper investigation of the delimitation of these species, hence the reason why we decided to follow the treatment of Abreu (2015). According to this author, only P. clematidea occurs in Rio Grande do Sul, and the species can be distinguished from P. diffusa by the shorter peduncles and the capitula in tighter corymbs.

Eupatorium clematideum Griseb. is a later homonym of E. clematideum (Wall. ex DC.) Sch.Bip. King & Robinson (1970b) seem to have overlooked this fact during the reestablishment of Praxelis and the recombination of Grisebach’s name. Veldkamp (1999) noted the illegitimacy of the name and proposed E. catarium as a new name for this species. However, following the Code Art. 58 ( Turland et al. 2018), the name used by King & Robinson (1970b) is to be treated as a legitimate replacement name for E. clematideum .

Specimens examined: — BRAZIL: Rio Grande do Sul: Alegrete: Ponte de Pedra [29°39’S, 55°23’W], 2 December 2016, Christ, A. L. 336 (ICN); Guaíba: Fazenda São Maximiano, 28August 2005, Matzenbacher, N. I. s.n. (ICN143476); 11 April 2010, Matzenbacher, N. I. s.n. (ICN183689); 1 May 2010, Matzenbacher, N. I. s.n. (ICN189944); s.l., 10 April 2007, Matzenbacher, N. I. s.n. (ICN150827); 10 April 2010, Matzenbacher, N. I. s.n. (ICN189958); Osório: trevo entre as rodovias Estrada do Mar e RS-030, 18 April 2015, Gonzatti, F. & Valduga, E. 1769 (HUCS). Santa Maria: Campo de Instrução de Santa Maria, 11 December 2012, Christ, A. L. 210 (SMDB). Santa Rosa : entre Santa Rosa e Giruá, 03 April 1979, Hagelund, K. 12735 (ICN). São Borja: s.l. [28°59’46.9’’S, 56°10’20.1’’W], 07 November 2007, Schneider, A. A. 1557 (ICN). Terra de Areia: s.l., 23 April 2005, Marchett, F. 193 (HUCS). Torres: s.l., 30 July 2005, Marchett, F. 340 (HUCS); Parque Estadual de Itapeva, 08 May 2017, Christ, A. L. 460 (ICN). Três de Maio: s.l., 20 December 2016, Christ, A. L. 344 (ICN).

Figures

FIGURE 2A–D: Praxelis clematidea. A. Fertile branch. B. Capitulum. C. Involucral bracts. D. Floret. E–H: Praxelis missionum. E. Fertile specimen. F. Capitulum. G. Involucral bracts. H. Floret.

FIGURE 3A–C: Praxelis clematidea. A. Fertile branch. B. Leaves. C. Primary capitulescence. D–E: Praxelis missionum. D. Fertile specimens. E. Capitulum. Credits: Sérgio Bordignon (A–B), Anderson Christ (C–E).

FIGURE 4: Distribution of P. clematidea (triangles) and P. missionum (circles) in Rio Grande do Sul.