Odontites, Ludwig, 1757

Brullo, Salvatore, Tomaselli, Valeria & Wagensommer, Robert Philipp, 2015, A new species of Odontites (Orobanchaceae) from southern Italy, Phytotaxa 213 (3), pp. 271-281 : 279

Key to the annual species of Odontites with glabrous corolla on the abaxial face

1. Corolla entirely yellow.......................................................................................................................................................................2

- Corolla entirely purplish, red-purplish or yellow below and purplish above.....................................................................................6

2. Stamen filament papillose..................................................................................................................................................................3

- Stamen filament glabrous...................................................................................................................................................................5

3. Plant viscous, capsule with 4 seeds ........................................................................................................................... O. viscosus s.str.

- Plant eglandular, capsule with 8–12 seeds.........................................................................................................................................4

4. Leaves 0.9–2 mm wide, calyx teeth 2–2.3 mm, corolla 7–8 mm long............................................................................... O. triboutii

- Leaves 2.5–3.5 mm wide, calyx teeth ca. 1 mm, corolla 5.5–7 mm long ........................................................................... O. citrinus

5. Leaves up to 16 mm wide, obscurely teethed at margin, calyx 3.5–4.5 mm long, sparsely hairy, calyx teeth 1–1.1 mm long, corolla ca. 8 mm long, anther thecae sparsely hairy....................................................................................................................... O. powellii

- Leaves up to 8 mm wide, usually not teethed, calyx 3.1–3.8 mm long, densely hairy above, calyx teeth 1.5–1.6 mm long, corolla ca. 10 mm long, anther thecae densely hairy.................................................................................................................. O. vulcanicus

6. Corolla lower lip on the adaxial surface with 2 prominent glandular ridges.....................................................................................7

- Corolla lower lip without glandular ridges.........................................................................................................................................8

7. Inflorescence 4–10 cm long, (8)12–20 flowered, calyx 4.5–7 mm long, corolla lower lip with lobes rounded, anthers 1.3–1.6 mm long, capsule 16-20 seeded............................................................................................................................................ O. rigidifolius

- Inflorescence 1.5–3 cm long, 5–12 flowered, calyx 4.5–5 mm long, corolla lower lip with lobes retuse, anthers 1.1–1.2 mm long, capsule 8-10 seeded.............................................................................................................................................................. O. sillettii

8. Corolla bicoloured, yellow below and purplish above....................................................................................................... O. foliosus

- Corolla entirely purplish or red-purplish............................................................................................................................................9

9. Stamen filament glabrous, anther thecae glabrous, tinged with violet............................................................................. O. violaceus

- Stamen filament papillose, anther thecae hairy, yellow or purplish red...........................................................................................10

10. Plant prostrate, corolla lower lip without glandular hairs on the adaxial surface, anther purplish red ....................... O. maroccanus

- Plant erect, corolla lower lip with glandular hairs on the adaxial surface, anther yellow or light brown........................................11

11. Calyx 2.5–4(4.8) mm long, with teeth 1.5–2 mm long .................................................................................................. O. purpureus

- Calyx 4–7 mm long, with teeth 2.5–3 mm long...............................................................................................................................12

12. Corolla lower lip lobes 1.2–1.4 mm long, anther 1.5–1.9 mm long, capsule 4 mm long .................................................. O. discolor

- Corolla lower lip lobes 1.8–2 mm long, anther 1.7–2.1 mm long, capsule 5 mm long ......................................................... O. lapiei