Flora of Dominica, Part 2 - Smithsonian Institution Libraries

NUMBER 77 ASTERACEAE 31
10. Heads sessile in leaf axils; ray-achenes with prominent, dentate
lateral wings ..................... Synedrella
10. Heads stalka ray-achenes without dentate lateral wings.
11. Heads many, in corymbose panicles ........ Clibadium
11. Heads few (1-3), often on long peduncles.
12. Petioles >1 cm long; involucre multiseriate; achenes with
many capillary setae .............. Melanthera
12. Petioles 4 cm long; involucre 1-2-senate; achenes with few
or no awns.
13. Receptacle with bristle-like pales .........
EcZipta
13. Receptacle with broad pales.
14. Leaves glabrous; receptacle columnar in fruit .....
........................ Acmella
14. Leaves pubescent; receptacle nearly flat . . Galinsoga
6. Heads without receptacular bracts (receptacle sometimes with short
hairs); heads homogamous (only bisexual, disciform florets); corollas
never yellow.
15. Leaves pinnately veined; lamina with internal resinous “dots,” seen
as pale against light. ................... Critonia
15. Leaves 3-veined from near base, without resinous “dots.”
16.
16. Pappus of many capillary bristles.
Pappus of 5 scales (awned in ours) .......... Ageratum
17. Climbers; heads with 4 major bracts enclosing 4 florets
............................ Mikania
17. Erect or lax herbs; heads with >4 bracts and 4 florets.
18. Involucral bracts dark-tipped, none spreading with age or
drying, all finally deciduous ........
Chromolaena
18. Involucral bracts concolored, at least outer bracts spreading
with age or drying, persistent.
19. Plants pubescent, particularly on stems; achene bases
asymmetric.
20. Leaves much longer than wide; involucre with 15 bracts
in 3 ranks; receptacles flat, naked; corolla limbs
abruptly expanded ........... Condylidium
20. Leaves about as wide as long; involucre with >15
bracts, not ranked; receptacles strongly convex,
hirsute .................. Hebeclinum
19. Plants glabrous; achene bases symmetric.
2 1. Lax herbs; corolla lobes papillose inside; apical anther
appendages longer than wide , . , . Flekchmannia
21. Erect herbs; corolla lobes not papillose inside; apical
anther appendages broader than long . ........
..................... Koanophyllon
1. Leaves alternate or basal.
22. Florets all ligulate with 5 lobes; sap usually milky.
23. Heads small (-5 mm long); inflorescence much longer than leafy part of plant;
achenes k terete ........................... Youngia
23. Heads longer; inflorescence much shorter than leafy part of plant; achenes
flattened.
24. Achenes narrowed or beaked at apex; leaves unlobed ....... Lactuca
24. Achenes truncate at apex; leaves lyrate .............. Sonchus
22. Florets not ligulate with 5 lobes; sap usually clear.
25. Female heads med with hooked spines in fruit. ......... Xanthium
25. Heads not armed with hooked spines in fruit.