Exacum Linnaeus 1753
Creators: name: Geethakumary, M. P.
name: Deepu, S.
name: Kissling, J.
name: Pandurangan, A. G.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Gentianales
Gentianaceae
Exacum

description: Key to Exacum species in the Western Ghats
1. Flowers 4-merous ...............................................................................................................................................................................2
- Flowers 5-merous ...............................................................................................................................................................................8
2. Calyx lobes without wings .................................................................................................................................................................3
- Calyx lobes with prominent wings .....................................................................................................................................................4
3. Flowers subsessile; calyx wings without prominent veins................................................................ E. sessile Linnaeus (1753: 112)
- Flowers pedicellate; calyx wings with prominent veins................................................................... E. lawii C.B. Clarke (1885: 98)
4. Leaves 3-veined (midvein with one secondary vein on each side) ...................................... E. pedunculatum Linnaeus (1753: 112)
- Leaves 5-veined (midvein with two secondary veins on each side) ..................................................................................................5
5. Anthers oblong ...................................................................................................................................................................................6
- Anthers linear .....................................................................................................................................................................................7
6. Leaves with a distinct petiole; calyx wings truncate ...................................................................... E. petiolare Grisebach (1845: 46)
- Leaves sessile; calyx wings cordate .............................................................................................. E. pumilum Grisebach (1845: 46)
7. Calyx lobes cuspidate with broad rounded dorsal wing; anthers curved ................................ E. tetragonum Roxburgh (1832: 398)
- Calyx lobes acuminate with a narrow dorsal wing; anthers straight ............................................ E. grande Klackenberg (1985: 43)
8. Dorsal side of the anther with a papilla present near the apex ...........................................................................................................9
- Dorsal side of the anther without a papilla.......................................................................................................................................14
9. Leaves petiolate or ± sessile.............................................................................................................................................................10
- Leaves amplexicaul or semiamplexicaul..........................................................................................................................................12
10. Perennial herbs; anthers oblong............................................................................ E. idukkianum Geethakumary et al. (2016a: 226)
- Annual herbs; anthers linear.............................................................................................................................................................11
11. Stem 4-angled, winged; fruiting pedicel drooping....................................................................... E. wightianum Arnott (1839: 176)
- Stem 4-lineolate, not winged; fruiting pedicel not drooping.................................................. E. klackenbergii Gopalan (2002: 271)
12. Style shorter than anthers ......................................................................................... E. keralense Geethakumary et al. (2016b: 429)
- Style longer than anther....................................................................................................................................................................13
13. Leaves ovate, papilla in the dorsal side of anther distinct.................................................... E. atropurpureum Beddome (1874: 24)
- Leaves elliptic, papilla in the dorsal side of anther indistinct ............................................ E. anamallayanum Beddome (1874: 33)
14. Succulent herbs with a pincushion habit ..........................................................................................................................................15
- Slightly to much-branched ascending herbs.................................................................................................................. E. laxiflorum
15 Flowers solitary, long-pedicellate.......................................................................................... E. travancoricum Beddome (1874: 24)
- Flowers in multiflorous cymes, short-pedicellate ....................................................................................................... E. courtallense
description: Published as part of Geethakumary, M. P., Deepu, S., Kissling, J. & Pandurangan, A. G., 2022, Revisiting the taxonomy of Exacum courtallense (Gentianaceae) and recognizing E. courtallense var. laxiflorum at the species rank, pp. 185-192 in Phytotaxa 559 (2) on page 191, DOI: 10.11646/phytotaxa.559.2.7, http://zenodo.org/record/7021601