Key to distinguish the species of Lobelia sect. Rhynchopetalum in South America

1. Flowers with corolla tube unilabiate, with the apex of lobes connate; color white or greenish-white ..............................................2

- Flowers with corolla tube sub-bilabiate, seldom unilabiate, with apex of lobes free; color usually in shades of purple or pink, seldom whitish....................................................................................................................................................................................3

2. Stem and leaves glabrous; pedicels sigmoid, bracteoles, if present, in the middle of pedicel; hypanthium hemispheric; seeds winged ....................................................................................................................................................................... L. exaltata Pohl.

- Stem and leaves densely tomentose; pedicels erect, with two bracteoles in the apex of pedicel; hypanthium obconic to ellipsoid; seeds not winged..................................................................................................................................................... L. hassleri Zahlbr.

3. Leaves tomentose, at least in the abaxial face....................................................................................................................................4

- Leaves glabrous..................................................................................................................................................................................7

4. Leaves tomentose in both surfaces; seeds shortly winged ..................................................................... L. thapsoidea Schott ex Pohl

- Leaves tomentose only in abaxial surface; seeds widely winged.......................................................................................................5

5. Leaves with yellowish tomentum; corolla and ovary densely tomentose ......................... L. brasiliensis A.O.S.Vieira & G.J.Sheph.

- Leaves with whitish tomentum; corolla and ovary glabrous to sparsely tomentose ..........................................................................6

6. Leaves sparsely tomentose on abaxial surface; rachis of inflorescence, pedicels and hypanthium glabrous; calyx lobes patent, not curved, greenish colored................................................................................................................................... L. organensis Gardner

- Leaves tomentose on abaxial surface; rachis of inflorescence, pedicels and hypanthium densely tomentose; calyx lobes erect, curvedtowards the center of the flower, purple colored ..................................................................... L. bahiana G.P.Coelho, sp.nov

7. Different shades along the flower and/or the inflorescence; corolla unilabiate; lateral lobes of the corolla 3.0 cm long or longer, convolute ................................................................................................................................................ L. capixaba Rollim & Trovó

- Single tone along the flower and/or the inflorescence; corolla sub-bilabiate; lateral lobes of the corolla up to 2.5 cm long, nonconvolute ............................................................................................................................................................................................8

8. Bracts sub-orbicular, with apex mucronate, tomentose.................................................................................... L. santos-limae Brade

- Bracts lanceolate, elliptic or narrowly elliptic, with apex acute, glabrous.........................................................................................9

9. Latex yellowish; inflorescence congest; flowers with pedicels up to 10 mm long; corolla lobes with a filiform elongated apex, resembling a horn in the bud ............................................................................................................. L.hilaireana (Kanitz) E.Wimm.

- Latex white; inflorescence lax; flowers with pedicels ca. 20 mm long; corolla lobes with acute apex, not elongated ...................10

10. Bracts erect, larger (35–55 mm long), usually covering the flowers in exsiccates; pedicel erect, winged, bracteoles absent ............ ................................................................................................................................................................................... L. fistulosa Vell.

- Bracts deflexed, shorter (up to 30 mm long), not covering the flowers in exsiccates; pedicel sigmoid, not winged, bracteoles present or absent ...............................................................................................................................................................................11

11. Corolla tube tomentose in the outer face; bracteoles conspicuous (ca. 10 mm long), with ciliate margin ........... L. langeana Dusén

- Corolla tube glabrous in the outer face; bracteoles shorter (ca. 1 mm long), with sub-entire margin, or absent.............................12

12. Hypanthium conspicuous, hemispheric; capsule adnate to hypanthium near its half portion; seeds shortly winged.......................... .......................................................................................................................................................................... L. glazioviana Zahlbr.

- Hypanthium reduced, briefly hemispheric; capsule almost entirely free of the hypanthium; seeds widely winged ........................... .......................................................................................................................................................................... L. organensis Gardner