Blumea axillaris ( Lamarck 1786: 84 ) Candolle (1836: 434)

Teles, Aristônio Magalhães & Heiden, Gustavo, 2024, Blumea axillaris (Inuleae, Asteraceae): the first record of an invasive exotic weed in the Americas and the first record of the genus in Brazil, Phytotaxa 670 (3), pp. 175-180 : 176-178

Blumea axillaris ( Lamarck 1786: 84) Candolle (1836: 434) . ( Figures 1 and 2 )

Annual aromatic herbs, up to 1.5 m tall, sometimes woody at the base with one or more shoots; whole plant viscid. Taproot tuberous in old specimens. Stems erect, terete, densely villous and glandular. Leaves simple, alternate, spirally arranged, smaller toward the apex, petiolate; lamina 1.9–15 × 1.5–6 cm, basal leaves lyrate, caulinar leaves elliptic to ovate, base and apex obtuse, margins erose to lacerate, sinuate, penninerved, densely villous and glandular on both faces; petioles 3–5 mm long, villous and glandular. Capitulescence axillary, terminal, lax to densely paniculate. Capitula heterogamous, disciform; peduncle 3–15 mm long, densely villous and glandular, ebracteolate; involucre 4–5 × 3–4 mm, urceolate, calyculate; calycular bract 1, ca. 1.5 mm long, lanceolate, densely villous and glandular; phyllaries 3-seriate, lanceolate to linear, gradually smaller externally, first series phyllaries ca. 1.1 × 0.1 mm, second series phyllaries ca. 2.2 × 0.2 mm, third series phyllaries ca. 3.3 × 0.1 mm, apex acute, scarious margins, densely villous and dorsally glandular; receptacle flat to convex (at maturity), alveolate. Outer florets ca. 100, pistillate, in ca. 11 rows, corolla filiform, 2.5–3 × 0.2 mm, whitish, apex shortly 2–3-dentate, glabrous; style ca. 4 mm long, style-branches ca. 0.5 mm long. Inner florets 11–13, bisexual, corolla tubulose, pale purple, 3.5 × 0.7 mm, 5-lobed, lobes 0.5 mm long, dorsally glandular; anthers 1.2–1.5 mm long, dark purple, anther bases calcarate, tailed, apical anther appendages oblong; style 4–4.5 mm long, style-branches 0.5 mm long, apex subulate, sweeping hairs up to the bifurcation point, base cylindrical. Cypselae 0.8–1 mm long, narrowly fusiform, 3-ribbed, slightly setuliferous, carpopodium annuliform, inconspicuous; pappus ca. 3 mm long, uniseriate, capillary, composed of barbellate bristles, whitish, persistent.

Examined specimens: — BRAZIL. Goiás: Goiânia, Setor Jaó, Parque Municipal Maracanã - Iolane Prudente Marques, 16º38′45″S, 49º13′40″W, 712 m, 28 September 2021, A. M. Teles, A. O. Teles & J. O. Teles 40/2021 ( ECT, UFG) ; ibidem, Setor Jaó, Parque Liberdade, 16º38′57″S, 49º14′4″W, 04 August 2022, A. M. Teles & A. C. Cercilian 30/2022 ( UFG) ; ibidem, Setor Jaó, estacionamento do Educandário Yara, 16º38′55″S, 49º13′24″W, 09 August 2022, A. M. Teles 31/2022 ( UFG) ; ibidem, Setor Jaó, esquina da Rua J-12 com a Alameda Maracanã, 16º38′44″S, 49º13′46″W, 21 August 2022, A. M. Teles 32/2022 ( UFG) ; ibidem, Setor Jaó, Parque Beija-Flor, 16º39′4″S, 49º13′48″W, 19 July 2023, A. M. Teles 120/2023 ( UFG) ; ibidem, Setor Itatiaia, UFG, campus Samambaia, em frente ao almoxarifado do IQ, 16º36′10″S, 49º15′43″W, 17 August 2023, A. M. Teles 121/2023 ( UFG) ; ibidem, Setor Central, Rua 18, terreno baldio, 16º40′39″S, 49º15′17″W, 17 August 2023, A. M. Teles 122/2023 ( UFG) ; Chácaras Recreio Samambaia, 16º35′17″S, 49º16′47″W, 27 August 2023, A. M. Teles 124/2023 ( UFG) ; Roselândia, margem do Rio Caldas, Chácara da Dona Gleide , 16º51′5″S, 49º5′24″W, 19 August 2023, A. M. Teles, J. O. Teles & A. O. Teles 123/2023 ( UFG) .

Distribution and ecology: — Blumea axillaris is widespread throughout Asia and Africa, but it is also found in Australia and New Caledonia ( Randeria 1960, eFloras 2008). We document its first report in the Americas and the first report of the genus in Brazil. According to Randeria (1960), eFloras (2008), and Pornpongrungrueng et al. (2016), the species is commonly found in dry fields, on hillslopes, along roadsides, on old walls, and in other disturbed and anthropic areas. In Brazil, the species was found, so far, in urban and rural disturbed areas in the state of Goiás, specifically in the municipalities of Goiânia and Bela Vista de Goiás (Roselândia district) ( Figure 2 ).

Phenology:— Specimens in florets and fruits were collected between July and September, which is the dry season in the Cerrado biome.

Discussion:— A single specimen of Blumea axillaris was observed and collected in 2021, making it the first record of this species in Brazil. In 2022, new collections of the species were made near the area where it was initially recorded, with a remarkable increase in frequency and broader dispersion of the original population. In 2023, the species was collected again, with a significant increase in population and a notable dispersion of them. As stated by Nesom (1983), all species of the genus have an efficient mechanism for anemochorous dispersal facilitated by the pappus. Randeria (1960) noted that the genus is expanding its geographic range. This was supported by the records of Blumea from places where it had not been previously reported. The origin of B. axillaris in the Americas remains unknown, with questions on how and when it was introduced. It may be impossible to determine the exact date of the dispersal event that introduced B. axillaris to the Americas. However, the first author’s observations over the past twenty-five years, especially in Brazil, strongly suggest a recent introduction since older specimens than the current ones were not found up to now. Nevertheless, we can make some hypotheses. The less likely one is the natural dispersion by migratory water birds. The more plausible scenario is the facilitation of diaspore dispersion through contamination linked to animal fur or human clothing, along with the importation of potted plants, crop seeds, or agricultural machinery as discussed by Davies & Sheley (2007). In any case, this record serves as a warning since it is an invasive exotic species that, by all indications, has already become well-established as a weed and can represent significant challenges for agriculture and the environment. In Brazil, Inuleae is represented by 22 species grouped into five genera ( Monge et al. 2017, Monge & Semir 2024). Considering the new record reported in this work, the number of genera of the tribe Inuleae in Brazil increases to six and the number of species to 23.

Figures

FIGURE 1. Blumea axillaris. A. Apical part of the plant with the upper leaves and capitulescence. B. Basal part of the plant with the lower leaves. C. Taproot. D. Variation of the leaf blade. E. Detail of the capitulescence. F. Disciform capitulum. G. Capitulum dispersing the cypselae. H. Capitulum with the convex and alveolate receptacle after releasing the cypselae. I. Florets in detail, the outer filiform and pistillate floret (on the right-hand side) and the inner tubulose and bisexual floret (on the left-hand side). A.–I. by A.M. Teles.

FIGURE 2. Geographical distribution map showing the distribution of Blumea axillaris in Brazil.