Plantago australis subsp. hirtella (Kunth 1817: 229) Rahn (1964: 50)

Hassemer, Gustavo, Trevisan, Rafael, Meudt, Heidi M. & Rønsted, Nina, 2015, Taxonomic novelties in Plantago section Virginica (Plantaginaceae) and an updated identification key, Phytotaxa 221 (3), pp. 226-246 : 234-235

Plantago australis subsp. hirtella (Kunth 1817: 229) Rahn (1964: 50)

≡ P. hirtella Kunth in von Humboldt et al. (1817: 229); = P. bicallosa Decaisne (1852: 725) ; = P. cantagallensis Zahlbr. ex Wawra in von Fernsee (1888: 56); = P. galeottiana Decaisne (1852: 726) ; = P. leptophylla Decaisne (1852: 723) ; = P. schiedeana Decaisne (1852: 723) ; = P. veratrifolia Decaisne (1852: 721–722) . Type:—“Herb. Mus. Paris. Herbier Humboldt & Bonpland Amerique equatoriale. Plantago hirtella ” (holotype P, photograph!).

See description in Rahn (1974).

Illustration: —Figure 31 in Rahn (1974).

Phenology: —In Arizona and Mexico mainly June–August; in Central America, Venezuela, Ecuador and Peru throughout the year; in Bolivia and northwestern Argentina January–March, and in northeastern Argentina, Paraguay and Brazil mainly November–December ( Rahn 1974). This subspecies may flower throughout the year throughout its wide range, although flowering seems to be concentrated during spring in southern South America.

Habitat and distribution: —This subspecies occurs from southwestern USA (Arizona) to northern Argentina and Uruguay through Mexico, Central America, the Andes and southern Brazil ( Rahn 1974), from sea level to 3000 m asl, but is absent from tropical lowlands. Its original habitat was most probably natural clearings in subtropical forests ( Rahn 1974). However, this subspecies has now a very broad ecological range, also occurring in high-altitude grasslands, coastal vegetation, and especially in disturbed habitats as a ruderal plant. This is the most widespread species or subspecies in Plantago section Virginica , and also the only one that tolerates some shading.

Conservation status: —Least Concern (LC). This subspecies is very frequent, and has a very large distribution and a relatively broad ecological range, including ruderal habitats.

Discussion: —The taxonomic situation of Plantago australis subsp. hirtella has been the subject of a recent yet quite significant (considering its continental distribution) misunderstanding. In their taxonomic revision of Plantago in the South region of Brazil, Hefler et al. (2011) affirmed that Luteyn et al. (1999) had synonymised P. australis subsp. hirtella under P. australis subsp. australis , and they further synonymised P. australis subsp. angustifolia also under P. australis subsp. australis . However, a careful reading of Luteyn et al. (1999) makes it clear that they did not propose any taxonomic changes, as they merely list the subspecies of P. australis that occur in the páramos (Andean high-elevation grasslands). Personal communication (March 2015) with James Luteyn confirmed that Luteyn et al. (1999) did not propose any synonymisation in P. australis . Despite this, the taxonomic changes proposed by Hefler et al. (2011) have been broadly accepted, and were followed, for instance, by important plant catalogues such as the Argentine “Catálogo de las Plantas Vasculares del Cono Sur” (http://www2.darwin.edu.ar/proyectos/floraargentina/ fa.htm) and the Brazilian “Lista de Espécies da Flora do Brasil ” (http://www.floradobrasil.jbrj.gov.br).

The careful examination of a great number of collections, in addition to field work and a thorough bibliographic revision have convinced us that P. australis subsp. australis and P. australis subsp. hirtella are distinct, and can be separated by their morphology, distribution and ecology; we thus agree with Rahn (1964, 1966, 1974, 1975, 1979, 1995, 1999) in recognising these two subspecies.

It is evident that even though Rahn worked extensively on P. australis , it is still poorly resolved at the species level, as Rahn himself admitted ( Rahn 1966, 1974). However, the synonymisation of P. australis subsp. hirtella under P. australis subsp. australis , in addition to being a misunderstanding as explained above, is a clear regression in the understanding of this species complex. To solve this notoriously confusing species complex it will probably be necessary, in addition to examining material from throughout its vast distribution range (which was not done by Hefler et al. 2011), to employ molecular phylogenetic techniques. To date we consider that the available knowledge supports the recognition of both P. australis subsp. australis and P. australis subsp. hirtella . In addition to the information presented by Rahn (1974), we found two more morphological characters that can be used to separate these two subspecies: the width of the secondary cord-like roots, and the distribution of the trichomes on the scape ( Table 3).