First record of Plantago heterophylla Nutt . ( Plantaginaceae ) for the Brazilian flora

We present the first record of Plantago heterophylla Nutt. (Plantaginaceae) to Brazil, based on specimens from Rio Grande, Rio Grande do Sul, Brazil. The species is easily recognized due to its linear leaves, 2 stamens, and pixidium with 10 –30 seeds. Plantago heterophylla is considered native from United States and Mexico, but it is distributed as adventitious in the east of Argentina, Paraguay, and Uruguay. Images from the species and a distribution map illustrating its occurrence in the American continent are provided.


Introduction
Plantago L. (Plantaginaceae) comprises about 250 species (Rahn 1996, Hassemer et al. 2015).It is a cosmopolitan genus composed of annual or perennial herbs or, rarely, subshrubs (Rønsted et al. 2002), distributed mainly in temperate and tropical altitude zones (Pilger 1937, Rahn 1996).The genus is defined by a set of morphological features, such as paralelinervous leaves, with axillary hairs, scale shaped corolla and absence of an apparent disc, dried stigma usually bilobate, protoginic flowers, anthers with an extension of connective present, and pollen grains with 4-15 apertures (Rahn 1996, Souza and Souza 2002, Hefler et al. 2011).
Several species of Plantago are known for being globally invasive in crops, such as P. australis Lam., P. lanceolata L., and P. major L. (Lorenzi 1982, Meudt 2012), these herbs also being used in traditional medicine as phytotherapics (Hefler et al. 2011).Although several species are cosmopolitan, the genus presents rare and endangered species, as in the case of P. turficola Rahn and P. corvensis Hassemer (Hassemer et al. 2016), and/ or endemic to reduced areas, such as some oceanic islands of Atlantic Ocean, for example, P. trinitatis Rahn (Rahn 1974) and P. moorei Rahn (Meudt 2012).
Currently, 20 species of Plantago are recorded from Brazil (Souza andHassemer 2015, Hassemer et al. 2016), with 3 of those being exotic species introduced from Europe (Hefler et al. 2011, Hassemer 2016).The southern region of the country presents the higher richness for the genus, encompassing more than 90% of the species recorded from Brazil.
We provide the first record of P. heterophylla for Brazil and present a short description, images from the collected specimens and habitat, and a map of occurrence of the species for the American continent.

Methods
During an update of the inventory of the campus "Carreiros", "Universidade Federal do Rio Grande" flora, published by Jacobi et al. (2013), several P. heterophylla specimens were collected in places under strong anthropic influence.For species identification, the plants were compared with images of type specimens and descriptions available.The collected specimens were deposited at herbarium HURG.For illustrating the sites of occurrence of P. heterophylla in South America, a map was prepared using the QGIS software, version 3.2.2(QGIS Development Team).

Discussion
Plantago heterophylla is easily recognized by its linear leaves, pixidium with 10-30 seeds and bearing 2 stamens only.Due to its linear leaves (Fig. 1), P. heterophylla may be misidentified as P. brasiliensis Sims or P. commersoniana Decne., which have linear-lanceolate leaves.However, these are easily distinguished from P. heterophylla by having only 2 seeds for pixidium, and these two are distinguishable from each other by the corolla symmetry, which is actinomorphic in P. commersoniana and zygomorphic in P. brasiliensis (Hefler et al. 2011).
The new records of P. heterophylla were collected with flowers and fruits from October to December.The species has preference for plain and humid soils (Rahn, 1979), being usually invasive in crops (Bassett 1966).Plantago heterophylla has disjunct distribution, being recorded from North and South America (Fig. 2).In North America, it is well distributed in southwest of United States, where it is considered native, being documented for several states, such as Florida, Missouri, Georgia, Alabama, Tennessee and others (Bassett 1966, Hassemer et al. 2015).Recently, it has been recorded from the northwestern Mexican states of Sonora and Baja California (Villaseñor 2016).In South America, P. heterophylla was first reported on 13 February 1876 in material collected by G. Hieronymus, deposited in the herbarium of the Universität Göttingen (GOET 008755).This specimen was used as type material for description of Plantago aquatilis Griseb.by A. Grisebach (1879), now considered synonymous of P. heterophylla (Bassett 1966).
Plantago heterophylla was recorded as a common species for Paraguay and eastern Argentina, mainly in the provinces of Corrientes and Entre Ríos (Rahn 1979).In Uruguay, where it was recorded by Hassemer et al. (2015) and Hassemer and Marchesi (2016), the species is considered rare and of restricted distribution, being included in the list of priority species for conservation (Marchesi et al. 2013).In Brazil, our record shows that the species is, for now, known only for the state of Rio Grande do Sul, in the southern extreme coastal lowlands, in the city of Rio Grande (Fig. 2).There is no information in the available literature that discusses the disjointed occurrence of P. heterophylla in American continent.As the species original description was based on the material collected in USA by T. Nuttall, the species is likely to be native of North America.This idea is reinforced, considering that P. section Micropsyllium is restricted to the northern hemisphere, particularly in the temperate regions (Ishikawa et al. 2009).Rahn (1996) also cites the natural occurrence of P. heterophylla for USA, but points that there are also records for from Argentina and Paraguay, which are more than 100 years old.The citation made by Rahn (1996) indicates that there might have been a misconception in pointing out P. heterophylla as exotic invasive species for South America.

Figure 1 .
Figure 1.Plantago heterophylla Nutt. A. Image of P. heterophylla from the new record.B. Detail of the inflorescence.C. Details of the pixidium and seeds.Photographs by W. Matzenauer.

Figure 2 .
Figure 2. Current distribution of P. heterophylla in America, evidencing the bicentric occurrence of the species.Black dots indicate previously known records.The new records are indicated by a red star.Acronyms: USA -United States; MEX -Mexico; PRY -Paraguay; URY -Uruguay; ARG -Argentina.Source: the authors.