Cosmos section Discopoda

Castro-Castro, Arturo, Harker, Mollie, Vargas-Amado, Georgina & Rodríguez, Aarón, 2013, Two new species of Cosmos section Discopoda (Coreopsideae: Asteraceae) from Jalisco, Mexico, Phytotaxa 146 (2), pp. 35-49 : 46-47

Key to the species of Cosmos section Discopoda

1. Plants semiaquatic, from a long rhizome with fibrous roots; leaves pinnatisect, segments simple or elliptic-lobed; outer phyllaries elliptic-obovate, obtuse; ray florets white; achenes exaristate; from central Jalisco, Mexico.............. ................................................................................................................................................................... C. mcvaughii

1. Plants of upland habitats, from a short woody rhizome with tuberous roots; leaves various; outer phyllaries deltoid, lanceolate, ensiform, trullate or penicilliform, acuminate; ray florets purple, violet or white; achenes usually awned; ample distribution ........................................................................................................................................................ 2

2. Plants often scapose to subscapose; heads 1(3–5); peduncles 10–45 cm; petioles 1.5–9 (15) cm, frequently longer than leaves..................................................................................................................................................................... 3

2. Plants leafy caulescent; heads 3–6(–9), peduncles 10–20(–40) cm; petioles 0.5–2(–4) cm, shorter than the leaves or completely sessile ......................................................................................................................................................... 7

3. External phyllaries 1.0–2.5 × 0.3–0.6 cm; from South America ( Argentina, Bolivia and Peru) ..... C. peucedanifolius

3. External phyllaries 0.5–1.0 × 0.1–0.3 cm; from Mexico.............................................................................................. 4

4. Disk and ray florets dark purple; from Guanajuato, Hidalgo, Querétaro and San Luis Potosí ......... C. atrosanguineus

4. Disk florets yellow, ray florets white, violet to light purple ......................................................................................... 5

5. Leaves mostly bipinnate (rarely tripinnate); primary leaflets 3–5(–7), on unwinged rachis, the larger ones petiolulate and again divided; secondary leaflets 1.5–5 mm wide; petioles 1.5–7(–9) cm, often as long as the blade; heads prevailingly solitary (rarely 2–3) on terminal peduncles 15–35(–45) cm; external phyllaries 6–8, linear-lanceolate; ray florets 5–8, white; pappus awns lacking; from central western Jalisco, Mexico................................... C. deficiens

5. Leaves simple, pinnatifid or pinnate; leaflets 3–5, on partially winged rachis, 0.5–2.5 cm wide; petioles 3–5 cm, generally shorter than the blades (when longer, the terminal leaflet is dentate and twice as large as the lateral leaflets); heads 1–5 on terminal peduncles 10–45 cm; external phyllaries 8–10, linear-oblanceolate; ray florets 8, violet to purple (sometimes nearly white); pappus awns 2–4(–6); central and southern Mexico................................ 6

6. Leaves simple, pinnatifid or pinnate; all leaflets similar, entire; heads 3–7 cm wide across the extended rays; external phyllaries 8, oblong-lanceolate to oblanceolate; ample distribution in Mexico to Guatemala......................... ................................................................................................................................................................ C. diversifolius

6. Leaves pinnate; terminal leaflet larger than the laterals, denticulate; heads 2.5–4 cm wide across the extended rays; external phyllaries 8–10, linear-lanceolate; from Taxco, Guerrero, Mexico............................................ C. schaffnerii

7. Disk florets yellow (rarely with purple lobes) .............................................................................................................. 8

7. Disk florets dark purple, occasionally yellow with purple lobes................................................................................ 18

8. Ray florets reflexed to reclinate; leaves pinnatisect; from Oaxaca, Mexico................................................................ 9

8. Ray florets spreading; leaves simple, lobed, pinnatifid or pinnatisect; from Mexico................................................ 10

9. Leaves 2.5–7.5 cm long, 1.5–5 cm wide, 2–3 pinnatisect; petioles 0.7–2 cm; synflorescence 3–18 heads; heads 2–4 cm wide across the reflexed rays; external phyllaries 8, 5– 9 mm long, 1–2 mm wide; ray florets 7–10, dark purple to reddish; ligules 1.2–1.6 cm long; disk florets 18–32; achenes 1–1.3 cm long, 1–2 mm wide; from Juxtlahuaca, Oaxaca, Mexico................................................................................................................................ C. juxtlahuacensis

9. Leaves 4–11 cm long, 4–9 cm wide, bipinnatisect, sessile or with winged petioles 1.5–2.5 cm; heads solitary, 4.5– 7.5 cm wide across the reflexed to reclinate rays; external phyllaries 6–8, 1– 2.5 cm long, 5–7 mm wide; ray florets 8–10, dark red; ligules 2–2.5 cm long; disk florets 51–80; achenes 1.5–2.5 cm long, 2–3 mm wide; from San María Lachixio, Oaxaca; Mexico........................................................................................................................... C. nelsonii

10. Leaves sessile or with petioles 3 mm; ray florets light to dark purple or violet; disk florets yellow ......................... 11

10. Leaves petiolate; petioles 1–4(–9) cm; ray florets white, violet or dark purple; disk florets various ........................ 13

11. Leaves tomentose on both faces; ray florets violet; disk florets 50–80; external phyllaries (5–)7–8, 5– 9 mm long, 3– 4 mm wide, with 5 conspicuous resiniferous ducts on the abaxial face; from Guachinango, Jalisco, Mexico.............. ....................................................................................................................................................... C. pseudoperfoliatus

11. Leaves glabrous or only pubescent on the central vein of the adaxial face; ray florets violet or dark purple; disk florets 10–30; external phyllaries 8, 5– 7 mm long, 1–1.5 mm wide, with 3 conspicuous resiniferous ducts on the abaxial face ................................................................................................................................................................. 12

12. Lobes of the cauline leaves usually undivided, oblong to lanceolate, 5–8 mm wide; ray florets white, violet or dark purple .............................................................................................................................................................. C. sessilis

12. Lobes of the cauline leaves often divided, linear to lanceolate, 1–3 mm wide; ray florets light to dark purple ............ ...................................................................................................................................................................... C. stellatus

13. Petioles 0.3–1.5(–2) cm; leaves simple, pinnatisect or bipinnatisect; segments linear, 0.4–3.5 cm long, 1–3(–5) mm wide; ray florets white or violet; from northwestern Mexico..................................................................................... 14

13. Petioles (1–)2–6(–9) cm; leaves bipinnatisect to tripinnatisect; segments linear-lanceolate to lanceolate or oblanceolate, 0.3–1.5 cm long, 3–6 mm wide; ray florets white, dark purple; from Central Jalisco, Mexico........... 15

14. Heads 3–6 cm wide across extended rays; peduncles 15–30 cm; disk florets 25–30.................................... C. palmeri

14. Heads 5–7.5 cm wide across extended rays; peduncles 30–40 cm; disk florets 35–50................................. C. pringlei

15. Leaves pinnate or bipinnate; petioles slender, 1.5–9 cm ............................................................................................ 16

15. Leaves simple or pinnate, decurrent; sessile or with petioles up to 2.5 cm ................................................................ 17

16. Leaves 10–23 cm long; petioles 3–9 cm; terminal segments 0.3–1 cm wide; heads 3–6, peduncles 7–16(–27) cm; from Ayutla, Jalisco, Mexico............................................................................................................. C. longipetiolatus

16. Leaves 5–7(–10) cm long; petioles 1.5–3 cm; terminal segments, 1–2 mm wide; heads 1–2; peduncles 15–25 cm; from Santiago Tenango, Oaxaca, Mexico....................................................................................................... C. sherffii

17. Stems puberulent; ray florets violet; leaves ferruginous below, light green above; external phyllaries 6–8; disk florets 21–30, yellow; from southern Estado de México, Mexico.............................................................. C. modestus

17. Stems glabrous; ray florets violet, light or dark purple; leaves concolour; external phyllaries 8; disk florets 25–45, yellow or with purple lobes; from Durango, Jalisco, Nayarit and Zacatecas, Mexico............................... C. montanus

18. External paleae tubular enveloping and isolating disk florets .................................................................................... 19

18. External paleae not tubular nor enveloping disk florets ............................................................................................. 20

19. Plants scapose to subscapose; leaves simple or bipinnate; leaflets ovate to lanceolate, entire, rounded; peduncle 30– 60 cm; achenes glabrous to strigillose above, pappus awns 2–4; from Sierra Madre Oriental in Guanajuato, Hidalgo, Querétaro and San Luis Potosí, Mexico............................................................................................. C. atrosanguineus

19. Plants leafy caulescent; leaves pinnate; leaflets lanceolate, dentate, cuneate; peduncles 15–27 cm; achenes glabrous, pappus awns 2; from Sierra Madre del Sur in Coahuayutla, Guerrero, Mexico......................................... C. mattfeldii

20. Ray florets violet......................................................................................................................................................... 21

20. Ray florets purple to dark purple ................................................................................................................................ 22

21. Internodes (2–) 5–15 cm; leaves bipinnate; leaflets rhomboid-ovate or deltoid-ovate, glabrescent on both faces, terminal leaflets frequently exceeding the laterals; leaflet margins 4–5 dentate below; from Sultepec, Estado de México, Mexico.............................................................................................................................................. C. nitidus

21. Internodes 2.5–6.5(–11) cm; leaves pinnate; leaflets ovate-lanceolate, hirsute on both faces, terminal leaflets almost equal to the laterals; leaflet margins entire or 1–4 dentate above; from Estado de México, Guerrero and Morelos, Mexico....................................................................................................................................................... C. purpureus

22. External phyllaries ovate to deltoid; from Durango, Mexico...................................................................... C. concolor

22. External phyllaries linear-lanceolate; ample distribution in Mexico.......................................................................... 23

23. Leaves pinnatisect; segments (3–)5(–7), linear, glabrous, 4–14 cm long, 2–5 mm wide; petioles 2–3 cm; external phyllaries 7–8(–10); from Zapopan, Jalisco, Mexico........................................................................... C. ramirezianus

23. Leaves simple, lobed, pinnate or ternate; leaflets 3–5, ovate to lanceolate, pubescent, 2–4 cm long, 1.5–3 cm wide; petioles 0.3–2.5 cm; external phyllaries 8; ample distribution ................................................................................... 24

24. Leaves simple, lobed or pinnate; leaflets 3–5; petioles 3–5 mm; internal phyllaries purple; ray florets light to dark purple; disk florets 20–50, yellow with purple lobes; ample distribution in Mexico............................ C. scabiosoides

24. Leaves ternate; petioles 0.8–2.5 cm; internal phyllaries translucent with a purple apex; ray florets dark purple; disk florets 20–35, yellow with purple lobes or sometimes purple; from Atenguillo and Mascota, Jalisco, Mexico............ ................................................................................................................................................................... C. jaliscensis