Plantago, von Linne, 1753

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 : 236-237

Key to the species of Plantago in Brazil, Paraguay, Uruguay and northeastern Argentina

Abbreviations : Argentine provinces: CC— Chaco ; CR— Corrientes; ER— Entre Ríos; FO— Formosa; MN— Misiones ; SE— Santiago del Estero; SF— Santa Fe. Brazilian states: ES— Espírito Santo ; MG—Minas Gerais; MS— Mato Grosso do Sul ; PR— Paraná ; RJ— Rio de Janeiro ; RS— Rio Grande do Sul ; SC—Santa Catarina; SP— São Paulo. PY— Paraguay. UY— Uruguay .

Notes: Non-native species are marked with an asterisk. Plantago lanceolata and P.major , due to their ruderal ecology, can potentially be found in the entire area covered by this key.

1. Subshrubs. Aerial stem woody, to 34 cm long [ES] ......................................................................................................... P. trinitatis

- Herbs. Conspicuous woody aerial stem lacking................................................................................................................................ 2

2. Leaves pinnatifid. Corolla tube pubescent or villous [RS; UY] .................................................................................. * P. coronopus

- Leaf margins entire or dentate. Corolla tube glabrous ..................................................................................................................... 3

3. Leaves linear. Stamens 2. Seeds 10–25 [CR, ER; PY; UY] ..................................................................................... * P. heterophylla

- Leaves linear to ovate or obovate. Stamens 4. Seeds 1–31 .............................................................................................................. 4

4. Leaves ovate, with a very evident petiole ........................................................................................................................................ 5

- Leaves linear to obovate, basally attenuated, with the petiole not clearly distinct from the lamina ................................................ 6

5. Taproot absent, substituted by many unthickened secondary roots. Trichomes on scape antrorse. Seeds 6–31 [—] ........ * P.major

- Taproot very long and thicker than 10 mm, or more commonly absent, being substituted by thick secondary roots (to 6 mm). Trichomes on scape patent but becoming retrorse on maturity of the inflorescence. Seeds 1–4 [SC] ................................ P. corvensis

6. Scape at least 3.5 times longer than spike. Seeds 2, ventral side deeply concave ........................................................................... 7

- Scape normally shorter or equal to the length of the spike, rarely to 3 times longer in dwarf plants. Seeds 1–31, ventral side flattened, convex, or moderately concave ............................................................................................................................................. 8

7. Leaves linear to narrow-lanceolate. Bract with apex obtuse to acuminate. Anterior sepals connate only at base. Corolla zygomorphic, with posterior lobe narrower, and curved at a higher point relative to the other lobes [CR, ER; RS, SC; UY] .. P. brasiliensis

- Leaves lanceolate to elliptic-lanceolate. Bract with long-cuspidate apex. Anterior sepals connate for nearly entire length. Corolla actinomorphic [—] ...................................................................................................................................................... * P. lanceolata

8. Taproot thick, without secondary roots. Trichomes on scape variously directed, silky, relatively slender, not very perceptibly tapering towards the apex. Seeds rugose [CC, CR, ER, FO, MN, SE, SF; MG, PR, RJ, RS, SC, SP; PY; UY] .................. P. tomentosa

- Taproot present or absent, with or without secondary roots. Trichomes on scape antrorse or patent, not silky, stiff and wide, very perceptibly tapering towards the apex. Seeds reticulate ................................................................................................................... 9

9. Trichomes on leaves and scape very thin, without conspicuous cellular articulations and not tapering towards the apex ........... 10

- Trichomes on leaves and scape relatively wide, with very conspicuous cellular articulations, gradually tapering towards the apex ......................................................................................................................................................................................................... 12

10. Caudex globose. Leaves elliptic, oblanceolate, or obovate. Seeds 2–3 [MG, PR, RJ, RS, SC, SP] ........................ P. guilleminiana

- Caudex elongated and thickened. Leaves linear to elliptic-lanceolate. Seeds 1–3 ........................................................................ 11

11. Caudex growing vertically. Leaves linear to narrow-lanceolate, pilose or rarely glabrous, with variously-directed trichomes, sometimes long and silky, but never producing a shiny appearance on both faces [ES, MG, MS, PR, RS, SC; PY; UY] ......................... ............................................................................................................................................................................... P. commersoniana

- Caudex growing horizontally. Leaves elliptic-lanceolate, with densely distributed, short, antrorse trichomes on both faces, which produces a shiny appearance [SC] ................................................................................................................................... P. rahniana

12. Trichomes on scape antrorse, generally appressed, but sometimes only very slightly pointing upwards ..................................... 13

- Trichomes on scape patent ............................................................................................................................................................. 19

13. Taproot present. Cord-like secondary roots absent ........................................................................................................................ 14

- Taproot absent. Cord-like secondary roots present ........................................................................................................................ 16

14. Taproot unthickened. Leaves narrow-lanceolate. Trichomes on scape very sparsely distributed, rather inconspicuous [CR, ER; RS; UY] .................................................................................................................................................................................. P. penantha

- Taproot thickened. Leaves elliptic to obovate. Trichomes on scape more or less densely distributed, but always very conspicuous ......................................................................................................................................................................................................... 15

15. Leaves hirsute. Seeds 3 [UY] ............................................................................................................................................... P. berroi

- Leaves glabrous. Seed 1 [UY] ......................................................................................................................................... P. dielsiana

16. Caudex thickened and very conspicuous, to 10 cm long. Leaves glabrous, becoming black, or almost so, on drying; apex acuminate. Bract glabrous [MG, PR, RJ] .................................................................................................................................. P. pretoana

- Caudex generally inconspicuous, rarely to 5 cm long. Leaves glabrous to pilose, becoming only slightly darker on drying; apex acuminate to obtuse. Bract ciliate ................................................................................................................................................... 17

17. Leaves narrow-elliptic, pilose; margin denticulate; apex acuminate. Spike shorter than the scape [RJ] ............................................ ........................................................................................................................................................... P. australis subsp. angustifolia

- Leaves elliptic to obovate, glabrous to pilose; margin generally edentate; apex acute to obtuse. Spike equalling or exceeding the length of the scape .......................................................................................................................................................................... 18

18. Secondary roots to 3 mm wide. Caudex to 3 (–5) cm long. Leaves glabrous to glabrescent. Trichomes on scape concentrated in the upper half of the scape, lower half glabrous to glabrescent [CR, ER, SF; RS, SC; UY] ....................... P. australis subsp. australis

- Secondary roots to 1.5 mm wide. Caudex to 2 cm long. Leaves pilose. Trichomes on scape more or less evenly distributed along the entire length of the scape [CC, CR, FO, MN; MG, PR, RJ, RS, SC, SP; PY; UY] ........................... P. australis subsp. hirtella

19. Taproot absent. Leaf apex acuminate. Scape usually with sparsely distributed trichomes. Seeds 1–2 [RS, SC] ............ P. turficola

- Taproot present. Leaf apex acuminate to obtuse. Scape usually with densely distributed trichomes. Seeds 3 .............................. 20

20. Taproot unthickened. Leaves narrow-lanceolate to lanceolate; apex acuminate. Ventral side of seed convex [CC, CR, ER, FO, SE, SF; RS; PY; UY] .................................................................................................................................. P. myosuros subsp. myosuros

- Taproot thickened or unthickened. Leaves elliptic to oblanceolate; apex acute to obtuse. Ventral side of seed flattened to convex. ......................................................................................................................................................................................................... 21

21. Taproot thickened, swollen above. Caudex very short, generally inconspicuous. Trichomes on leaves and scape long and stiff, generally brownish. Ventral side of seed generally convex [CC, CR, FO, MN, SF; RS; PY] ..................................... P. napiformis

- Taproot unthickened. Caudex elongated and unthickened, very conspicuous in older plants. Trichomes on leaves and scape short and stiff, generally whitish. Ventral side of seed generally flattened [PR, RJ, RS, SC, SP] ........................................ P. catharinea