Plantago commersoniana Decaisne & Barnéoud

Hassemer, Gustavo, 2017, Contributions to the knowledge of the genus Plantago (Plantaginaceae) in the Central-West region of Brazil, Phytotaxa 316 (1), pp. 1-21 : 11

Plantago commersoniana Decaisne & Barnéoud in Barnéoud (1845: 37)

Type: — URUGUAY. Montevideo, 1767, P. Commerson s.n. (lectotype [designated by Rahn 1974: 104] P-00680451!; isolectotype C-10016652!). Image of the lectotype available at: https://science.mnhn.fr/institution/mnhn/collection/p/item/p00680451 .

Description: —Rosette herbs, perennial. Taproot generally present, thickened, or, if absent, then substituted with thickened secondary roots. Caudex often growing vertically, to 4 cm long, often with a conspicuous tuft of reddish trichomes at its apex. Leaves linear to narrowly lanceolate, basally attenuated, without a very evident petiole, membranaceous to papiraceous, densely covered with silvery trichomes. Trichomes on leaves and scapes wire-shaped, with inconspicuous cellular articulations, very slender throughout their entire length, not perceptibly gradually tapering towards the apex (type K); those on scapes variously directed. Scape covered with trichomes throughout the entire length, or almost. Spike multiflowered, with flowers relatively sparsely distributed, less densely crowded below. Corolla actinomorphic, glabrous, remaining very conspicuous after fruit maturation. Stamens 4. Pyxidia 1–2-seeded. Seeds slightly convex to slightly concave ventrally, convex dorsally; surface reticulate.

Illustrations: — Fig. 6 in Rahn (1966); Fig. 44 in Rahn (1974); Fig. 2 (L–P, U–V) in Hefler et al. (2011); Fig. 3 (A–H) in Hassemer et al. (2014).

Photographs: — Fig. 8 ; Figs. 1 and 3 (B) in Hassemer & Marchesi (2016); Fig. 5 (A) in Hassemer (2016); Fig. 6 in Hassemer (2017).

Distribution: —Scattered across Uruguay, south-eastern Paraguay and Brazil: South region and Distrito Federal territory ( Fig. 7 ).

Habitat: —Stony grasslands subject to no or low anthropic impact, at 100–1700 m asl.

Conservation status: —Endangered (EN–B2[a,b(i,ii,iii,iv,v)]). Plantago commersoniana has a scattered and considerably disjunct distribution, which is most probably a relict of a past time when the climate in the area was colder and drier. Importantly, with extensive field observations in Uruguay and southern Brazil I could verify that this species is very sensitive to anthropic impact, particularly shading (due to forest planting) and soil fertilising. In all cases when this has happened, this species disappeared completely from areas where it has been collected in the past. On the contrary, low to moderate grazing by bovines seems to favour its survival (along of many other rare herbaceous species), by preventing the natural advance of forests over its natural relict environments: shallow stony grasslands.

The new record unfortunately does not improve the conservation status of P. commersoniana , which is declining all over its distribution range, and disappearing from some areas. Therefore, I recommend immediate attempts to relocalise this population in Brasília, and the implementation of measures to favour its survival there, such as the expulsion of the illegal constructions and occupants in the Reserva Biológica do Guará, and the monitoring and in-situ and ex-situ conservation measures for the species.

Notes: —The new record ( Fig. 8 ) was discovered during the revision of images of specimens kept at the CEN herbarium. The new record is impressive ca. 1120 km distant from the nearest known population of P. commersoniana , in Guarapuava municipality, Paraná state, southern Brazil. Furthermore, it is the first record of this species in Brazil outside the South region of this country. As it was already stated, this discovery is remarkable, as it represents, along with the new record of P. australis from Distrito Federal (see above), the northernmost records of native Plantago species in South America outside of the Andes.

Additional specimens examined: — BRAZIL. DISTRITO FEDERAL: Brasília: Reserva Ecológica do Guará, 1035 m, 2 September 1993, G.P. da Silva 1773 (CEN-19986).

Figures

FIGURE 1. Lectotype of Plantago hirtella (A.J.A. Bonpland & F.W.H.A. von Humboldt s.n., P-00670059). Published with permission of Muséum National d’Histoire Naturelle.Available online at: https://science.mnhn.fr/institution/mnhn/collection/p/item/p00670059.

FIGURE 2. Lectotype of Plantago galeottiana (H.Galeotti 1427, P-00609788).Published with permission of Muséum National d’Histoire Naturelle.Available online at: https://science.mnhn.fr/institution/mnhn/collection/p/item/p00609788.

FIGURE 3. Lectotype of Plantago leptophylla (A. Isabelle s.n., P-03530099). Published with permission of Muséum National d’Histoire Naturelle.Available online at: https://science.mnhn.fr/institution/mnhn/collection/p/item/p03530099.

FIGURE 5. Lectotype of Plantago veratrifolia (H.Galeotti 1422, P-00609787).Published with permission of Muséum National d’Histoire Naturelle.Available online at: https://science.mnhn.fr/institution/mnhn/collection/p/item/p00609787.

FIGURE 6. Specimen of Plantago australis subsp. hirtella from Brasília (R.C. Mendonça & B.A.S. Pereira 193, HRB-21010). Published with permission of Tânia Jost (Herbário RADAMBRASIL).

FIGURE 7. Distribution of Plantago commersoniana (purple squares, the new record in orange), P. hatschbachiana (red triangles) and P. napiformis (green dots, the new records in yellow); the new records of P. australis subsp. hirtella in the Central-West region of Brazil (blue diamonds); and the new records of P.major in Mato Grosso state (pink stars). The area in the map shaded in blue corresponds to the states in Brazil where the occurrence of P. australis subsp. hirtella had been hitherto recorded.

FIGURE 8. Specimen of Plantago commersoniana from Brasília (G.P. da Silva 1773, CEN-19986). Published with permission of Taciana Barbosa Cavalcanti (Empresa Brasileira de Pesquisa Agropecuária).