Chromolaena squarrosoramosa (Hieronymus) King & Robinson (1970c: 206)

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 : 185-187

2.14. Chromolaena squarrosoramosa (Hieronymus) King & Robinson (1970c: 206) .

Eupatorium squarrosoramosum Hieronymus (1897: 753) . Lectotype (designated by Freire & Ariza Espinar 2014b: 338):— ARGENTINA . Tucuman: Estancia de la Cruz, 20–24 March 1872, P.G. Lorentz 187 (CORD! [CORD00005361], isolectotypes CORD! [CORD00005362, CORD000005363])

= Eupatorium oyadense Hieronymus (1897: 755) . Chromolaena oyadensis (Hieron.) King & Robinson (1970c: 204) . Lectotype (designated by Freire & Ariza Espinar 2014b: 338):— ARGENTINA . Salta: La Oyada, 05 February 1873, P.G. Lorentz & G. Hieronymus 1203 (CORD! [CORD00005351])

= Eupatorium oyadense var. paraguayense Hieronymus (1897: 756) . Lectotype (designated by Freire & Ariza Espinar 2014b: 338):— PARAGUAY. Esperanza, September 1892, O. Kuntze s.n. (NY! [NY169133]). ( Fig. 22E–I , 28A–B ).

Subshrubs, up to 1 m tall, erect, xylopodium absent, branched only in capitulescence; stems puberulous to hirsute, glandular or eglandular, leafy until capitulescence. Leaves 3.3–8.6 × 0.5–3.4 cm, opposite, petiolate, 3-veined, leaf blade ovate to lanceolate, papyraceous to chartaceous, apex attenuate to obtuse, base cuneate to attenuate, margins crenate to serrate in apical half, entire in basal half, adaxial surface strigose, eglandular, abaxial surface strigose to hirsute, glandular, margins ciliate, petioles 0.1–3.2 cm long, hirsute, eglandular. Primary capitulescences dichasia. Secondary capitulescences compound dichasium, axis puberulous to hirsute, glandular, bracteate, bracts 0.7–4.9 × 0.2–2.2 cm, petioles 0.1–0.5 cm long, hirsute, eglandular. Capitula long pedunculate, peduncles 2.1–4.8 cm long, puberulous to hirsute, glandular, involucres campanulate, 6.2–8.7 × 3.4–6 mm, involucral bracts 30–50, 6–8-seriate, outer oblong, 1.7–3.6 × 1–1.9 mm, apex rounded to cuneate, citrine, ciliate, puberulous, glandular, recurved to squarrose, rarely slightly recurved, abaxial surface stramineous to citrine, 3–5-veined, glabrous, inner linear to rarely spatulate, 5.6–7.3 × 0.5–1 mm, apex rounded to cuneate, pink to vinaceous, non-petaloid, ciliate or eciliate, glabrous to puberulous, eglandular or rarely glandular, slightly recurved to erect, abaxial surface stramineous to citrine, 1–3- veined, glabrous, receptacles epaleate or rarely paleate, paleae 1–2, linear, 7.5–8.5 × 0.1–0.2 mm, 1-veined, apex stramineous to pink, abaxial surface stramineous, ciliate, eglandular. Florets 39–60, corollas 3–5.4 × 0.4–0.6 mm, lilac, lobes glabrous, glandular. Cypselas obconical, 2.6–3 × 0.3–0.6 mm, 5–6-ribbed, ribs and sinuses setuliferous to glabrescent, eglandular, pappus setae ca. 20–26, white, 3.8–4.8 mm long.

Distribution: — Argentina , Bolivia, Paraguay ( Freire & Ariza Espinar 2014b) and Brazil. In Brazil, it occurs in Mato Grosso, Mato Grosso do Sul and Rio Grande do Sul. In Rio Grande do Sul, it occurs only in the municipalities of Uruguaiana and Barra do Quaraí, in the physiographic region of Campanha ( Fig. 24 , triangles).

Habitat: —Grasslands with occurrence of Vachellia caven (Molina) Seigler & Ebinger ( Fabaceae ) (vernacular name “espinilho”) in the Pampa biome.

Phenology: —Flowers from the end of summer to the beginning of autumn, with a flowering peak in March and April.

Etymology: —Latin squarrulosus (diminutive of squarrosus: squarrose) and ramosus (branched), in reference to the curvature of the apex of the outer involucral bracts and the large, very branched capitulescences with several capitula.

Comments: — Chromolaena squarrosoramosa is typical of grasslands in the westernmost part of Rio Grande do Sul, sharig this distribution pattern in the state with C. christieana . Both species are more common in foreign countries and are considered rare in Rio Grande do Sul. This species is confirmed here as occurring in the state: the only specimens collected before our study and identified as C. squarrosoramosa were Bastos s.n. (deposited in MPUC) and Sobral 3909 (deposited in ICN and consisting actually of misidentified branches of C. pedunculosa ).

Chromolaena squarrosoramosa shows a great variation in the shape and size of the leaves, the indumentum of the stems and the curvature of the outer involucral bracts. Sometimes, these variations can be associated with certain points of its geographic distribution: some specimens collected in Bolivia, Paraguay, Argentina and in the Brazilian states of Mato Grosso and Mato Grosso do Sul bear large ovate leaves, with attenuate bases, sparser indumentum in the leaves and stems and outer involucral bracts slightly recurved to erect. These characters were not observed in the specimens collected in Rio Grande do Sul and some collections of Argentina . This morphotype seems to correspond to E. squarrosoramosum f. umbrosum Malme , which was described by Malme (1931) based on specimens collected in Mato Grosso. We could not find enough material of this morphotype, nor the type specimens of E. squarrosoramosum f. umbrosum , therefore it is not possible to guarantee the existence of a morphological continuum between these specimens and those collected in Rio Grande do Sul. The lectotype of E. squarrosoramosum designated by Freire & Ariza Espinar (2014b) is very similar to the specimens found in Rio Gande do Sul, and the few specimens studied suggest that a continuum between these two morphotypes may indeed exist. Thus, we have decided to consider these specimens as belonging to a single species before further taxonomic decisions can be taken.

The most similar species to C. squarrosoramosa to occur in Rio Grande do Sul is C. callilepis . The differences between both taxa were commented upon under the descripton of the former.

Specimens examined: — BRAZIL: Rio Grande do Sul: Barra do Quaraí: Parque Estadual do Espinilho, 15 March 1996, Bastos , A. s.n. ( MPUC20581 ) ; [30°11’S, 57°29’W], 01 December 2016, Christ , A. L. 333 ( ICN). Uruguaiana: Quaraí-Chico, Cabanha Letícia, 20 November 1988, Beneton, G. 298 ( HAS) .

Figures

FIGURE 22A–D: Chromolaena rhinanthacea. A. Fertile specimen. B. Capitulum. C. Involucral bracts. D. Floret. E–I: Chromolaena squarrosoramosa. E. Fertile branch. F. Capitulum. G. Involucral bracts. H. Floret. I. Palea.

FIGURE 24: Distribution of C. squarrosoramosa (triangles) and C. squarrulosa (circles) in Rio Grande do Sul.

FIGURE 28A–B: Chromolaena squarrosoramosa. A. Primary capitulescence. B. General view. C–D: Chromolaena squarrulosa. C. Secondary capitulescence. D. Leaves. E–F: Chromolaena verbenacea. E. Secondary capitulescence. F. Leaves. Credits:Anderson Christ (A–C, E–F) and Sérgio Bordignon (D).