Vernonia, Schreber, 1791

Redonda-Martínez, Rosario, Villaseñor, José Luis & Campos-Villanueva, Alvaro, 2016, A new species of Vernonia (Asteraceae, Vernonieae) from the state of Oaxaca, Mexico, Phytotaxa 282 (3), pp. 211-217 : 216-217

Artificial key to the Mexican species of Vernonia s.str.

1. Plants mainly distributed in Northern Mexico, generally with tomentose stems, occasionally pilose, puberulent or glabrescent .. 2

– Plants distributed in Central and Southern Mexico, rarely in the north, generally with pilose or glabrous stems .......................... 8

2. Leaves sessile, petioles absent; blades linear, <8 mm wide ............................................................................................................ 3

– Leaves short petiolate, petioles> 3 mm, blades lanceolate or elliptical,> 1.2 mm wide ................................................................ 6

3. Pappus purple; heads with 30 or less florets .................................................................................................................................... 4

– Pappus white; heads with 40 or more florets .................................................................................................................................... 5

4. Stems tomentose; phyllaries and abaxial surface of leaves with tomentose indumentum .......................................... V. lindheimeri

– Stems puberulent or glabrous; phyllaries and abaxial surface of leaves with pilose–glandular indumentum .............. V. marginata

5. Cypselae with glandular indumentum; inflorescences with 10 or more heads; plants known from Coahuila .................. V. larsenii

– Cypselae with sericeous indumentum; inflorescences with 4 or less heads; plants known from Durango, Nayarit and Sinaloa ....... ........................................................................................................................................................................................... V. bolleana

6. Plants known from Coahuila; phyllaries pilose; cypselae with glandular indumentum ................................................. V. faustiana

– Plants known from Sonora; phyllaries tomentose; cypselae with pilose indumentum .................................................................... 7

7. Leaves elliptical; both surfaces of leaves with tomentose indumentum; involucre 5–6-seriate; phyllaries lanceolate; florets 50–60 per head; internal series of pappus <7 mm long ................................................................................................................ V. barclayi

– Leaves lanceolate; adaxial surface of leaves with pilose indumentum, abaxial surface tomentose; involucre 6–8-seriate; phyllaries linear–lanceolate; florets 30–40 per head; internal series of pappus> 10 mm long ......................................................... V. joyaliae

8. Involucre hemispheric; cypselae with glandular–pilose, or sometimes glandular indumentum ...................................................... 9

– Involucre campanulate or turbinate; cypselae with glandular indumentum ................................................................................... 10

9. Inflorescences cymose; involucre 4-seriate, phyllaries oblong–elliptical, purple, with pilose indumentum; plants unknown from Oaxaca ................................................................................................................................................................................ V. greggii

– Inflorescences corymbose; involucre 5–6-seriate, phyllaries linear–lanceolate, green, with apex purple, glabrescent; plants only known of Oaxaca ............................................................................................................................................................... V. confusa

10. Leaves lanceolate or lanceolate–elliptic; 30 or less florets per head .............................................................................................. 11

– Leaves ovate or ovate–elliptic; 40 or more florets per head .......................................................................................................... 12

11. Involucre campanulate; phyllaries triangular, glabrous; plants from Jalisco and Michoacan ........................................... V. bealliae

– Involucre turbinate; phyllaries lanceolate, sparcely pilose; plants from Guerrero and Oaxaca .......................................................... ................................................................................................................................................... V. karvinskiana subsp. karvinskiana

12. Apex of phyllaries aristate, awn> 2 mm long; cypselae> 5.0 mm long; internal series of pappus> 9 mm long; plants unknown from Oaxaca ..................................................................................................................................................................... V. alamanii

– Apex of phyllaries mucronate, mucro <1 mm long; cypselae <4.5 mm long; internal series of pappus <7 mm long; plants only known from Oaxaca ....................................................................................................................... V. karvinskiana subsp. inuloides