Key to the genera of the Astereae

1.

Capitula of 2 types usually on different plants, dioecious (subtribe Baccharidinae)

Baccharis

 

Capitula of one type

2

2. (1)

Ray floret limbs, when obvious, usually yellow or white; achenes often terete to fusiform

3

 

Ray floret limbs elongate and bluish to purple or white, rarely yellow, or limbs commonly reduced or lacking; achenes usually somewhat compressed (fusiform cylindrical in Neja , but ray limbs long and yellow or white)

7

3. (2)

Style appendages of fertile disc florets of hairs; phyllaries usually thickened or keeled

4

 

Style appendages of fertile disc florets of papillae, rarely hairy; phyllaries flattened, not keeled

5

4. (3)

Teeth and apices of leaves and phyllaries often spinulose-tipped; pappus setae often gradate (subtribe Machaerantherinae p.p.); pappus setae usually caducous; ray limbs yellow

Grindelia

 

Teeth and apices of leaves and phyllaries not spinulose-tipped; inner pappus setae distinctly longer than outer, or pappus setae subequal (subtribe Chrysopsidinae ); pappus setae persistent; ray limbs white

Noticastrum

5. (3)

Pappus (1-) 2 (-3)-seriate; leaves often tomentose beneath

17

 

Pappus uniseriate; leaves with little or no tomentum

6

6. (5)

Capitula solitary or few in clusters; pappus setae 1-2-seriate, of stiff scales

Gutierrezia

 

Inflorescences secund to thyrsoid of many capitula, rarely weakly corymbose; pappus setae uniseriate, capillary

Solidago

7. (2)

Phyllaries with orange-resinous ribs or veins (subtribe Conyzinae )

8

 

Phyllaries without prominent resinous veins

12

8. (7)

Female florets tubular or with short erect limbs

Conyza

 

Female florets with long limbs

9

9. (8)

Achenes fusiform-cylindrical with 7-10 prominent veins

Neja

 

Achenes compressed with 2 marginal veins

10

10. (9)

Pappus biseriate, outer setae short, paleaceous/scale-like, inner setae flexuous

Hysterionica

 

Pappus 1-3-seriate, of flexuous setae

11

11. (10)

Phyllaries usually with 1 resinous longitudinal vein

Erigeron

 

Phyllaries with 3 longitudinal veins

Leptostelma

12. (7)

Appendages of fertile disc styles hairy; phyllaries mostly herbaceous or with distinct apical green herbaceous area; pappus usually of capillary setae (subtribe Symphyotrichinae )

Symphyotrichum

 

Appendages of fertile disc styles papillose; phyllaries not usually with distinct apical patch; pappus of setae, reduced or absent

13

13. (12)

Pappus setae (1-)2-3-seriate; ray limbs sometimes elongate and coiling (subtribe Podocominae )

14

 

Pappus setae reduced or absent, rarely uniseriate; ray limbs short or absent

16

14. (13)

Achenes with distinct neck or beak

Podocoma

 

Achenes apically rounded or truncate, erostrate

15

15. (14)

Leaves all basal or basal and lower cauline; capitula solitary on scapes; disc ovaries sterile; achenes eglandular

Inulopsis

 

Leaves primarily cauline, basal leaves persistent in some species; capitula on leafy stems; disc ovaries fertile; achenes glandular

Laennecia

16. (13)

Perennial herbs; corolla of female florets bilabiate with lobes on inner side

Plagiocheilus

 

Annual herbs; corollas of female florets not bilabiate

Egletes

17. (5)

Receptacle paleaceous

Chiliotrichiopsis

 

Receptacle epaleaceous

18

18. (17)

Plants thorny (spines 1-3 cm long)

Ocyroe

 

Plants unarmed

19

19. (18)

Densely branched, cupressiform, persistently aromatic, resinous shrubs

Parastrephia

 

Herbs or shrubs not cupressiform, not notably aromatic

20

20. (19)

Capitula homogamous, lacking female florets; receptacles columnar with florets borne on narrow convex tip

Llerasia

 

Capitula heterogamous with marginal female florets

21

21. (20)

Female florets tubular or sub-bilabiate, usually 5-lobed; disc florets functionally male

22

 

Female florets usually with long or short limbs; disc florets perfect or functionally male

23

22. (21)

Female florets edentate or scarcely dentate at apex; small bromeliad-like rosettiform plants with thickened glabrous leaves; pappus biseriate

Novenia

 

Female corollas with 4 or 5 distinct narrow lobes; pappus absent

Laestadia

23. (21)

Herbs; stems simple, erect; leaves sessile in basal rosette; achenes glandular; ray limbs white

Oritrophium

 

Shrubs or trees; stems usually well-branched; leaves usually petiolate, cauline or in apical rosettes; achenes glabrous to sericeous, eglandular; ray limbs, when present, white, bluish, or purplish

Diplostephium