Thunbergia species

Key to the Thunbergia species in Vietnam

(*Native; # Introduced)

1. Erect shrubs ........................................................................................................................................................................... T. erecta #

- Climbers or twiners ............................................................................................................................................................................2

2. Woody climber; flowers in racemes, usually pendent........................................................................................................................3

- Herbaceous climber; flowers solitary in leaf axils. ............................................................................................................................9

3. Calyx reduced to an entire ring, untoothed…… ................................................................................................................................4

- Calyx bearing 5‒17 slender subulate lobes; irregularly many-toothed or sinuate, sometimes with 1‒2 linear lobes........................8

4. Ovary pubescent ............................................................................................................................................................... T. geoffrayi *

- Ovary glabrous. ..................................................................................................................................................................................5

5. Racemes terminal; anther thecae glabrous along the inner margin .................................................................................. T. coccinea *

- Racemes axillary or extra-axillary; anther thecae bearded along the inner margin. ..........................................................................6

6. Leaves palmatifid, 5‒7 nerved from base; one anther theca of posterior stamens spurred at base.............................. T. grandiflora *

- Leaves palmatifid, 3‒5 nerved from base; both anther thecae of posterior stamens muticous at base..............................................7

7. Bracteoles oblong to obovate, green or purple spots, 4‒5 cm long; corolla blue-violet, lobes opening out into five rounded, blue-violet................................................................................................................................................................................ T. laurifolia *

- Bracteoles ovate, purplish brown, 2.5 cm long; corolla yellow, lobes deflexed into tube, dark red............................. T. mysorensis #

8. Corolla less than 3 cm long; calyx irregularly many toothed, 4‒4.5 mm high ............................................................. T. eberhardtii *

- Corolla more than 3.5 cm long; calyx sinuate at margin, rim-like, unlobed, ca. 0.5 mm high, sometimes with 1‒2 linear lobes that are 1‒2 mm long.................................................................................................................................................................... T. hossei *

9. Petiole conspicuously winged; corolla orange with throat dark purple internally, anthers spurred at base........................... T. alata *

- Petiole wingless; corolla entirely white; anthers muticous at base ................................................................................... T. fragrans *